indent
: Indent and Format C Program SourceThis is Edition 2.2.12 of The indent
Manual,
for Indent Version 2.2.12, last updated 18 April 2021.
Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 2014, 2015 Free Software Foundation, Inc. Copyright (C) 1995, 1996 Joseph Arceneaux. Copyright (C) 1999 Carlo Wood. Copyright (C) 2001 David Ingamells. Copyright (C) 2013 Ćukasz Stelmach. Copyright (C) 2015 Tim Hentenaar.
Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.
Next: Indent Program, Previous: (dir), Up: (dir) [Contents][Index]
indent
: Indent and Format C Program SourceThe indent
program
changes the appearance of a C program by inserting or deleting whitespace.
This is Edition 2.2.12, 18 April 2021, of The indent
Manual,
for Indent Version 2.2.12.
• Indent Program | The indent Program
| |
• Option Summary | Option Summary | |
• Index | Index |
Next: Option Summary, Previous: Top, Up: Top [Contents][Index]
indent
ProgramThe indent
program
can be used to make code easier to read. It can also convert from one
style of writing C to another.
indent
understands a substantial amount about the syntax of C,
but it also attempts to cope with incomplete and misformed syntax.
In version 1.2 and more recent versions, the GNU style of indenting is the default.
• Invoking indent | Invoking indent
| |
• Backup files | Backup Files | |
• Common styles | Common styles | |
• Blank lines | Blank lines | |
• Comments | Comments | |
• Statements | Statements | |
• Declarations | Declarations | |
• Indentation | Indentation | |
• Breaking long lines | Breaking long lines | |
• Disabling Formatting | Disabling Formatting | |
• Miscellaneous options | Miscellaneous options | |
• Bugs | Bugs | |
• Copyright | Copyright |
Next: Backup files, Up: Indent Program [Contents][Index]
indent
As of version 1.3, the format of the indent
command is:
indent [options] [input-files] indent [options] [single-input-file] [-o output-file]
This format is different from earlier versions and other versions of
indent
.
In the first form, one or more input files are specified. indent
makes a backup copy of each file, and the original file is replaced with
its indented version. See Backup files, for an explanation of how
backups are made.
In the second form, only one input file is specified. In this case, or when the standard input is used, you may specify an output file after the -o option.
To cause indent
to write to standard output, use the -st
option. This is only allowed when there is only one input file, or when
the standard input is used.
If no input files are named, the standard input is read for input. Also, if a filename named - is specified, then the standard input is read.
As an example, each of the following commands will input the program slithy_toves.c and write its indented text to slithy_toves.out:
indent slithy_toves.c -o slithy_toves.out indent -st slithy_toves.c > slithy_toves.out cat slithy_toves.c | indent -o slithy_toves.out
Most other options to indent
control how programs are formatted.
As of version 1.2, indent
also recognizes a long name for each
option name. Long options are prefixed by either -- or
+.
1
In most of this document,
the traditional, short names are used for the sake of brevity.
See Option Summary, for a list of options, including both long and
short names.
Here is another example:
indent -br test/metabolism.c -l85
This will indent the program test/metabolism.c using the -br and -l85 options, write the output back to test/metabolism.c, and write the original contents of test/metabolism.c to a backup file in the directory test.
Equivalent invocations using long option names for this example would be:
indent --braces-on-if-line --line-length185 test/metabolism.c indent +braces-on-if-line +line-length185 test/metabolism.c
If you find that you often use indent
with the same options, you
may put those options into a file named .indent.pro.
indent
will look for a profile file in three places. First it will check
the environment variable INDENT_PROFILE
. If that exists its value
is expected to name the file that is to be used. If the environment variable does
not exist, indent looks for .indent.pro in the current directory
and use that if found. Finally indent
will search
your home directory for .indent.pro and use that file if it is
found. This behaviour is different from that of other versions of
indent
, which load both files if they both exist.
The format of .indent.pro is simply a list of options, just as they would appear on the command line, separated by white space (tabs, spaces, and newlines). Options in .indent.pro may be surrounded by C or C++ comments, in which case they are ignored.
Command line switches are handled after processing
.indent.pro. Options specified later override arguments
specified earlier, with one exception: Explicitly specified options
always override background options (see Common styles). You can
prevent indent
from reading an .indent.pro file by
specifying the -npro option.
Next: Common styles, Previous: Invoking indent, Up: Indent Program [Contents][Index]
As of version 1.3, GNU indent
makes GNU-style backup files, the
same way GNU Emacs does. This means that either simple or
numbered backup filenames may be made.
Simple backup file names are generated by appending a suffix to the original file name. The default for this suffix is the one-character string ~ (tilde). Thus, the backup file for python.c would be python.c~.
Instead of the default, you may specify any string as a suffix by
setting the environment variable SIMPLE_BACKUP_SUFFIX
to
your preferred suffix.
Numbered backup versions of a file momeraths.c look like
momeraths.c.~23~, where 23 is the version of this particular
backup. When making a numbered backup of the file src/momeraths.c,
the backup file will be named src/momeraths.c.~V~, where
V is one greater than the highest version currently existing in
the directory src. The environment variable VERSION_WIDTH
controls the number of digits, using left zero padding when necessary.
For instance, setting this variable to "2" will lead to the backup
file being named momeraths.c.~04~.
The type of backup file made is controlled by the value of the
environment variable VERSION_CONTROL
. If it is the string
‘simple’, then only simple backups will be made. If its value is
the string ‘numbered’, then numbered backups will be made. If its
value is ‘numbered-existing’, then numbered backups will be made if
there already exist numbered backups for the file being indented;
otherwise, a simple backup is made. If VERSION_CONTROL
is not
set, then indent
assumes the behaviour of
‘numbered-existing’.
Other versions of indent
use the suffix .BAK in naming
backup files. This behaviour can be emulated by setting
SIMPLE_BACKUP_SUFFIX
to ‘.BAK’.
Note also that other versions of indent
make backups in the
current directory, rather than in the directory of the source file as
GNU indent
now does.
Next: Blank lines, Previous: Backup files, Up: Indent Program [Contents][Index]
There are several common styles of C code, including the GNU style, the Kernighan & Ritchie style, and the original Berkeley style. A style may be selected with a single background option, which specifies a set of values for all other options. However, explicitly specified options always override options implied by a background option.
As of version 1.2, the default style of GNU indent
is the GNU
style. Thus, it is no longer necessary to specify the option
-gnu to obtain this format, although doing so will not cause an
error. Option settings which correspond to the GNU style are:
-nbad -bap -nbc -bbo -bl -bli2 -bls -ncdb -nce -cp1 -cs -di2 -ndj -nfc1 -nfca -hnl -i2 -ip5 -lp -pcs -nprs -psl -saf -sai -saw -nsc -nsob
The GNU coding style is that preferred by the GNU project. It is the style that the GNU Emacs C mode encourages and which is used in the C portions of GNU Emacs. (People interested in writing programs for Project GNU should get a copy of The GNU Coding Standards, which also covers semantic and portability issues such as memory usage, the size of integers, etc.)
The Kernighan & Ritchie style is used throughout their well-known book The C Programming Language. It is enabled with the -kr option. The Kernighan & Ritchie style corresponds to the following set of options:
-nbad -bap -bbo -nbc -br -brs -c33 -cd33 -ncdb -ce -ci4 -cli0 -cp33 -cs -d0 -di1 -nfc1 -nfca -hnl -i4 -ip0 -l75 -lp -npcs -nprs -npsl -saf -sai -saw -nsc -nsob -nss -par
Kernighan & Ritchie style does not put comments to the right of code in
the same column at all times (nor does it use only one space to the
right of the code), so for this style indent
has arbitrarily
chosen column 33.
The style of the original Berkeley indent
may be obtained by
specifying -orig (or by specifying --original, using the
long option name). This style is equivalent to the following settings:
-nbad -nbap -bbo -bc -br -brs -c33 -cd33 -cdb -ce -ci4 -cli0 -cp33 -di16 -fc1 -fca -hnl -i4 -ip4 -l75 -lp -npcs -nprs -psl -saf -sai -saw -sc -nsob -nss -ts8
The Linux style is used in the linux kernel code and drivers. Code generally has to follow the Linux coding style to be accepted. This style is equivalent to the following settings:
-nbad -bap -nbc -bbo -hnl -br -brs -c33 -cd33 -ncdb -ce -ci4 -cli0 -d0 -di1 -nfc1 -i8 -ip0 -l80 -lp -npcs -nprs -npsl -sai -saf -saw -ncs -nsc -sob -nfca -cp33 -ss -ts8 -il1
Next: Comments, Previous: Common styles, Up: Indent Program [Contents][Index]
Various programming styles use blank lines in different places.
indent
has a number of options to insert or delete blank lines in
specific places.
The -bad option causes indent
to force a blank line after
every block of declarations. The -nbad option causes
indent
not to force such blank lines.
The -bap option forces a blank line after every procedure body. The -nbap option forces no such blank line.
The -bbb option forces a blank line before every boxed comment (See Comments.) The -nbbb option does not force such blank lines.
The -sob option causes indent
to swallow optional blank
lines (that is, any optional blank lines present in the input will be
removed from the output). If the -nsob is specified, any blank
lines present in the input file will be copied to the output file.
• -bad | More on the -bad option. | |
• -bap | More on the -bap option. |
Next: -bap, Up: Blank lines [Contents][Index]
The -bad option forces a blank line after every block of declarations. The -nbad option does not add any such blank lines.
For example, given the input
char *foo; char *bar; /* This separates blocks of declarations. */ int baz;
indent -bad
produces
char *foo; char *bar; /* This separates blocks of declarations. */ int baz;
and indent -nbad
produces
char *foo; char *bar; /* This separates blocks of declarations. */ int baz;
Previous: -bad, Up: Blank lines [Contents][Index]
The -bap option forces a blank line after every procedure body.
For example, given the input
int foo () { puts("Hi"); } /* The procedure bar is even less interesting. */ char * bar () { puts("Hello"); }
indent -bap
produces
int foo () { puts ("Hi"); } /* The procedure bar is even less interesting. */ char * bar () { puts ("Hello"); }
and indent -nbap
produces
int foo () { puts ("Hi"); } /* The procedure bar is even less interesting. */ char * bar () { puts ("Hello"); }
No blank line will be added after the procedure foo
.
Next: Statements, Previous: Blank lines, Up: Indent Program [Contents][Index]
indent
formats both C and C++ comments. C comments are begun with
‘/*’, terminated with ‘*/’ and may contain newline characters.
C++ comments begin with the delimiter ‘//’ and end at the newline.
indent
handles comments differently depending upon their context.
indent
attempts to distinguish between comments which follow
statements, comments which follow declarations, comments following
preprocessor directives, and comments which are not preceded by code of
any sort, i.e., they begin the text of the line (although not
necessarily in column 1).
indent
further distinguishes between comments found outside of
procedures and aggregates, and those found within them. In particular,
comments beginning a line found within a procedure will be indented to
the column at which code is currently indented. The exception to this
is a comment beginning in the leftmost column; such a comment is output
at that column.
indent
attempts to leave boxed comments unmodified. The
general idea of such a comment is that it is enclosed in a rectangle or
“box” of stars or dashes to visually set it apart. More precisely,
boxed comments are defined as those in which the initial ‘/*’ is
followed immediately by the character ‘*’, ‘=’, ‘_’, or
‘-’, or those in which the beginning comment delimiter (‘/*’)
is on a line by itself, and the following line begins with a ‘*’ in
the same column as the star of the opening delimiter.
Examples of boxed comments are:
/********************** * Comment in a box!! * **********************/ /* * A different kind of scent, * for a different kind of comment. */
indent
attempts to leave boxed comments exactly as they are found
in the source file. Thus the indentation of the comment is unchanged,
and its length is not checked in any way. The only alteration made is
that an embedded tab character may be converted into the appropriate
number of spaces.
If the -bbb option is specified, all such boxed comments will be preceded by a blank line, unless such a comment is preceded by code.
Comments which are not boxed comments may be formatted, which means that the line is broken to fit within a right margin and left-filled with whitespace. Single newlines are equivalent to a space, but blank lines (two or more newlines in a row) are taken to mean a paragraph break. Formatting of comments which begin after the first column is enabled with the -fca option. To format those beginning in column one, specify -fc1. Such formatting is disabled by default.
The right margin for formatting defaults to 78, but may be changed with the -lc option. If the margin specified does not allow the comment to be printed, the margin will be automatically extended for the duration of that comment. The margin is not respected if the comment is not being formatted.
If the -fnc option is specified, all comments with ‘/*’ embedded will have that character sequence replaced by a space followed by the character ‘*’ thus eliminating nesting.
If the comment begins a line (i.e., there is no program text to its left), it will be indented to the column it was found in unless the comment is within a block of code. In that case, such a comment will be aligned with the indented code of that block (unless the comment began in the first column). This alignment may be affected by the -d option, which specifies an amount by which such comments are moved to the left, or unindented. For example, -d2 places comments two spaces to the left of code. By default, comments are aligned with code, unless they begin in the first column, in which case they are left there by default — to get them aligned with the code, specify -fc1.
Comments to the right of code will appear by default in column 33.
This may be changed with one of three options. -c will specify
the column for comments following code, -cd specifies the
column for comments following declarations, and -cp specifies
the column for comments following preprocessor directives #else
and #endif
. -dj together with -cd0 can be used
to suppress alignment of comments to the right of declarations, causing the
comment to follow one tabstop from the end of the declaration. Normally -cd0
causes -c to become effective.
If the code to the left of the comment exceeds the beginning column, the comment column will be extended to the next tabstop column past the end of the code, unless the -ntac option is specified. In the case of preprocessor directives,comments are extended to to one space past the end of the directive. This extension lasts only for the output of that particular comment.
The -cdb option places the comment delimiters on blank lines.
Thus, a single line comment like /* Loving hug */
can be
transformed into:
/* Loving hug */
Stars can be placed at the beginning of multi-line comments with the -sc option. Thus, the single-line comment above can be transformed (with -cdb -sc) into:
/* * Loving hug */
Next: Declarations, Previous: Comments, Up: Indent Program [Contents][Index]
The -br or -bl option specifies how to format braces.
The -br option formats statement braces like this:
if (x > 0) { x--; }
The -bl option formats them like this:
if (x > 0) { x--; }
If you use the -bl option, you may also want to specify the -bli option. This option specifies the number of spaces by which braces are indented. -bli2, the default, gives the result shown above. -bli0 results in the following:
if (x > 0) { x--; }
If you are using the -br option, you probably want to also use
the -ce option. This causes the else
in an if-then-else
construct to cuddle up to the immediately preceding ‘}’. For
example, with -br -ce you get the following:
if (x > 0) { x--; } else { fprintf (stderr, "...something wrong?\n"); }
With -br -nce that code would appear as
if (x > 0) { x--; } else { fprintf (stderr, "...something wrong?\n"); }
An exception to the behavior occurs when there is a comment between the right brace and the subsequent else statement. While the -br option will cause a left brace to jump over the comment, the else does not jump over the comment to cuddle because it has a strong likelihood of changing the meaning of the comment.
The -cdw option causes the while
in a do-while
loop to cuddle up to the immediately preceding ‘}’. For
example, with -cdw you get the following:
do { x--; } while (x);
With -ncdw that code would appear as
do { x--; } while (x);
The -slc option allows for an unbraced conditional and its inner statement to appear on the same line. For example:
if (x) x--; else x++;
Without -slc that code would appear as
if (x) x--; else x++;
The -cli option specifies the number of spaces that case labels
should be indented to the right of the containing switch
statement.
The default gives code like:
switch (i) { case 0: break; case 1: { ++i; } default: break; }
Using the -cli2 that would become:
switch (i) { case 0: break; case 1: { ++i; } default: break; }
The indentation of the braces below a case statement can be controlled with the -cbin option. For example, using -cli2 -cbi0 results in:
switch (i) { case 0: break; case 1: { ++i; } default: break; }
If a semicolon is on the same line as a for
or while
statement, the -ss option will cause a space to be placed before
the semicolon. This emphasizes the semicolon, making it clear that the
body of the for
or while
statement is an empty statement.
-nss disables this feature.
The -pcs option causes a space to be placed between the name of
the procedure being called and the ‘(’ (for example, puts ("Hi");
. The -npcs option would give puts("Hi");
).
If the -cs option is specified, indent
puts a space between
a cast operator and the object to be cast. The -ncs ensures that there
is no space between the cast operator and the object. Remember that indent
only knows about the standard C data types and so cannot recognise user-defined types
in casts. Thus (mytype)thing
is not treated as a cast.
The -bs option ensures that there is a space between the
keyword sizeof
and its argument. In some versions, this is
known as the ‘Bill_Shannon’ option.
The -saf option forces a space between a for
and the following parenthesis. This is the default.
The -sai option forces a space between a if
and the following parenthesis. This is the default.
The -saw option forces a space between a while
and the following parenthesis. This is the default.
The -prs option causes all parentheses to be separated with a space from whatever is between them. For example, using -prs results in code like:
while ( ( e_code - s_code ) < ( dec_ind - 1 ) ) { set_buf_break ( bb_dec_ind ); *e_code++ = ' '; }
Next: Indentation, Previous: Statements, Up: Indent Program [Contents][Index]
By default indent
will line up identifiers, in the column
specified by the -di option. For example, -di16 makes
things look like:
int foo; char *bar;
Using a small value (such as one or two) for the -di option can be used to cause the identifiers to be placed in the first available position; for example:
int foo; char *bar;
The value given to the -di option will still affect variables which are put on separate lines from their types, for example -di2 will lead to:
int foo;
If the -bc option is specified, a newline is forced after each comma in a declaration. For example,
int a, b, c;
With the -nbc option this would look like
int a, b, c;
The -bfda option causes a newline to be forced after the comma separating the arguments of a function declaration. The arguments will appear at one indention level deeper than the function declaration. This is particularly helpful for functions with long argument lists. The option -bfde causes a newline to be forced before the closing bracket of the function declaration. For both options the ’n’ setting is the default: -nbfda and -nbfde.
For example,
void foo (int arg1, char arg2, int *arg3, long arg4, char arg5);
With the -bfda option this would look like
void foo ( int arg1, char arg2, int *arg3, long arg4, char arg5);
With, in addition, the -bfde option this would look like
void foo ( int arg1, char arg2, int *arg3, long arg4, char arg5 );
The -psl option causes the type of a procedure being defined to
be placed on the line before the name of the procedure. This style is
required for the etags
program to work correctly, as well as some
of the c-mode
functions of Emacs.
You must use the -T
option to tell indent
the name of all the typenames in your
program that are defined by typedef
. -T can be specified
more than once, and all names specified are used. For example, if your
program contains
typedef unsigned long CODE_ADDR; typedef enum {red, blue, green} COLOR;
you would use the options -T CODE_ADDR -T COLOR.
The -brs or -bls option specifies how to format braces in struct declarations. The -brs option formats braces like this:
struct foo { int x; };
The -bls option formats them like this:
struct foo { int x; };
Similarly to the structure brace -brs and -bls options, the function brace options -brf or -blf specify how to format the braces in function definitions. The -brf option formats braces like this:
int one(void) { return 1; };
The -blf option formats them like this:
int one(void) { return 1; };
The -sar option affects how indent
will render initializer
lists. Without -sar they are formatted like this:
int a[] = {1, 2, 3, 4}; struct s { const char *name; int x; } a[] = { {"name", 0}, {"a", 1} };
With -sar they are formatted like this, with spaces inside the braces:
int a[] = { 1, 2, 3, 4 }; struct s { const char *name; int x; } a[] = { { "name", 0 }, { "a", 1 } };
Next: Breaking long lines, Previous: Declarations, Up: Indent Program [Contents][Index]
The most basic, and most controversial issues with regard to code
formatting is precisely how indentation should be acoomplished.
Fortunately, indent
supports several different styles of
identation. The default is to use tabs for indentation, which is
specified by the -ut option. Assuming the default tab size of
8, the code would look like this:
int a(int b) { return b; |------| 1 tab }
For those that prefer spaces to tabs, indent provides the -nut option. The same code would look like this:
int a(int b) { return b; |------| 8 spaces }
Another issue in the formatting of code is how far each line should be
indented from the left margin. When the beginning of a statement such
as if
or for
is encountered, the indentation level is
increased by the value specified by the -i option. For example,
use -i8 to specify an eight character indentation for each
level. When a statement is broken across two lines, the second line is
indented by a number of additional spaces specified by the -ci
option. -ci defaults to 0. However, if the -lp option is
specified, and a line has a left parenthesis which is not closed on that
line, then continuation lines will be lined up to start at the character
position just after the left parenthesis. This processing also applies
to ‘[’ and applies to ‘{’ when it occurs in initialization
lists. For example, a piece of continued code might look like this with
-nlp -ci3 in effect:
p1 = first_procedure (second_procedure (p2, p3), third_procedure (p4, p5));
With -lp in effect the code looks somewhat clearer:
p1 = first_procedure (second_procedure (p2, p3), third_procedure (p4, p5));
When a statement is broken in between two or more paren pairs (...), each extra pair causes the indentation level extra indentation:
if ((((i < 2 && k > 0) || p == 0) && q == 1) || n = 0)
The option -ipN can be used to set the extra offset per paren. For instance, -ip0 would format the above as:
if ((((i < 2 && k > 0) || p == 0) && q == 1) || n = 0)
indent
assumes that tabs are placed at regular intervals of both
input and output character streams. These intervals are by default 8
columns wide, but (as of version 1.2) may be changed by the -ts
option. Tabs are treated as the equivalent number of spaces.
By default, indent
will use tabs to indent as far as possible,
and then pad with spaces until the desired position is reached. However,
with the -as option, spaces will be used for alignment beyond
the current indentation level. By default, assuming -lp is
enabled, the code would be indented like so (‘t’ represents tabs,
‘s’ represents spaces):
unsigned long really_long_proc_name(unsigned long x, unsigned long y, int a) |------||-------||------||-------|__ t t t t ss { p1 = first_procedure (second_procedure (p2, p3), third_procedure (p4, p5)); |------||------||------|_____ t t t sssss }
This is fine, if you assume that whoever is reading the code will honor your assumption of 8-space tabs. If the reader was using 4-space tabs, it would look like this:
unsigned long really_long_proc_name(unsigned long x, unsigned long y, int a) |---||---||---||---|__ t t t t ss { p1 = first_procedure (second_procedure (p2, p3), third_procedure (p4, p5)); |---||---||---|______ t t t ssssss }
The -as option fixes this so that the code will appear consistent regardless of what tab size the user users to read the code. This looks like:
unsigned long really_long_proc_name(unsigned long x, unsigned long y, int a) ____________________________________ ssssssssssssssssssssssssssssssssssss { p1 = first_procedure (second_procedure (p2, p3), third_procedure (p4, p5)); |------|______________________ t ssssssssssssssssssssss }
The indentation of type declarations in old-style function definitions is controlled by the -ip parameter. This is a numeric parameter specifying how many spaces to indent type declarations. For example, the default -ip5 makes definitions look like this:
char * create_world (x, y, scale) int x; int y; float scale; { . . . }
For compatibility with other versions of indent, the option -nip is provided, which is equivalent to -ip0.
ANSI C allows white space to be placed on preprocessor command lines
between the character ‘#’ and the command name. By default,
indent
removes this space, but specifying the -lps option
directs indent
to leave this space unmodified. The option -ppi
overrides -nlps and -lps.
This option can be used to request that preprocessor conditional statements can be indented by to given number of spaces, for example with the option -ppi 3
#if X #if Y #define Z 1 #else #define Z 0 #endif #endif
becomes
#if X # if Y # define Z 1 # else # define Z 0 # endif #endif
This option sets the offset at which a label (except case labels) will be positioned. If it is set to zero or a positive number, this indicates how far from the left margin to indent a label. If it is set to a negative number, this indicates how far back from the current indent level to place the label. The default setting is -2 which matches the behaviour of earlier versions of indent. Note that this parameter does not affect the placing of case labels; see the -cli parameter for that. For example with the option -il 1
function() { if (do_stuff1() == ERROR) goto cleanup1; if (do_stuff2() == ERROR) goto cleanup2; return SUCCESS; cleanup2: do_cleanup2(); cleanup1: do_cleanup1(); return ERROR; }
becomes
function() { if (do_stuff1() == ERROR) goto cleanup1; if (do_stuff2() == ERROR) goto cleanup2; return SUCCESS; cleanup2: do_cleanup2(); cleanup1: do_cleanup1(); return ERROR; }
Next: Disabling Formatting, Previous: Indentation, Up: Indent Program [Contents][Index]
With the option -ln, or --line-lengthn, it is possible to specify the maximum length of a line of C code, not including possible comments that follow it.
When lines become longer than the specified line length, GNU indent
tries to break the line at a logical place. This is new as of version 2.1
however and not very intelligent or flexible yet.
Currently there are three options that allow one to interfere with the algorithm that determines where to break a line.
The -bbo option causes GNU indent
to prefer to break
long lines before the boolean operators &&
and ||
. The
-nbbo option causes GNU indent
not have that
preference. For example, the default option -bbo (together
with --line-length60 and --ignore-newlines) makes code
look like this:
if (mask && ((mask[0] == '\0') || (mask[1] == '\0' && ((mask[0] == '0') || (mask[0] == '*')))))
Using the option -nbbo will make it look like this:
if (mask && ((mask[0] == '\0') || (mask[1] == '\0' && ((mask[0] == '0') || (mask[0] == '*')))))
The default -hnl, however, honours newlines in the input file by giving them the highest possible priority to break lines at. For example, when the input file looks like this:
if (mask && ((mask[0] == '\0') || (mask[1] == '\0' && ((mask[0] == '0') || (mask[0] == '*')))))
then using the option -hnl, or --honour-newlines, together with the previously mentioned -nbbo and --line-length60, will cause the output not to be what is given in the last example but instead will prefer to break at the positions where the code was broken in the input file:
if (mask && ((mask[0] == '\0') || (mask[1] == '\0' && ((mask[0] == '0') || (mask[0] == '*')))))
The idea behind this option is that lines which are too long, but are already
broken up, will not be touched by GNU indent
. Really messy code
should be run through indent
at least once using the
--ignore-newlines option though.
The -gts option affects how the gettext standard macros _()
and N_()
are treated. The default behavior (or the use of -ngts) causes indent to
treat them as it does other functions, so that a long string is broken like the following
example.
if (mask) { warning (_ ("This is a long string that stays together.")); }
With the -gts option, the underscore is treated as a part of the string, keeping
it tied to the string, and respecting the fact that gettext is unobtrusively providing
a localized string. This only works if _("
is together as a unit at the beginning
of the string and ")
is together as a unit at the end.
if (mask) { warning (_("This is a long string that stays together.")); }
Next: Miscellaneous options, Previous: Breaking long lines, Up: Indent Program [Contents][Index]
Formatting of C code may be disabled for portions of a program by
embedding special control comments in the program. To turn off
formatting for a section of a program, place the disabling control
comment /* *INDENT-OFF* */
on a line by itself just before that
section. Program text scanned after this control comment is output
precisely as input with no modifications until the corresponding
enabling comment is scanned on a line by itself. The enabling control
comment is /* *INDENT-ON* */
, and any text following the comment
on the line is also output unformatted. Formatting begins again with
the input line following the enabling control comment.
More precisely, indent
does not attempt to verify the closing
delimiter (*/
) for these C comments, and any whitespace on the
line is totally transparent.
These control comments also function in their C++ formats, namely
// *INDENT-OFF*
and // *INDENT-ON*
.
It should be noted that the internal state of indent
remains
unchanged over the course of the unformatted section. Thus, for
example, turning off formatting in the middle of a function and
continuing it after the end of the function may lead to bizarre
results. It is therefore wise to be somewhat modular in selecting code
to be left unformatted.
As a historical note, some earlier versions of indent
produced
error messages beginning with *INDENT**
. These versions of
indent
were written to ignore any input text lines which began
with such error messages. I have removed this incestuous feature from
GNU indent
.
Next: Bugs, Previous: Disabling Formatting, Up: Indent Program [Contents][Index]
To find out what version of indent
you have, use the command
indent -version
. This will report the version number of
indent
, without doing any of the normal processing.
The -v option can be used to turn on verbose mode. When in
verbose mode, indent
reports when it splits one line of input
into two more more lines of output, and gives some size statistics at
completion.
The -pmt option causes indent
to preserve the access
and modification times on the output files. Using this option
has the advantage that running indent on all source and header
files in a project won’t cause make
to rebuild all targets.
This option is only available on Operating Systems that have the
POSIX utime(2)
function.
Next: Copyright, Previous: Miscellaneous options, Up: Indent Program [Contents][Index]
Please report any bugs to bug-indent@gnu.org.
When indent
is run twice on a file, with the same profile,
it should never change that file the second time. With the
current design of indent
, this can not be guaranteed,
and it has not been extensively tested.
indent
does not understand C. In some cases this leads to
the inability to join lines. The result is that running a file
through indent
is irreversible, even if the used input
file was the result of running indent
with a given profile
(.indent.pro).
While an attempt was made to get indent
working for C++, it
will not do a good job on any C++ source except the very simplest.
indent
does not look at the given --line-length option
when writing comments to the output file. This results often in comments
being put far to the right. In order to prohibit indent
from
joining a broken line that has a comment at the end, make sure that the
comments start on the first line of the break.
indent
does not count lines and comments (see the -v
option) when indent
is turned off with
/* *INDENT-OFF* */
.
Comments of the form /*UPPERCASE*/
are not treated as comment but as an
identifier, causing them to be joined with the next line. This renders
comments of this type useless, unless they are embedded in the code to
begin with.
Previous: Bugs, Up: Indent Program [Contents][Index]
The following copyright notice applies to the indent
program.
The copyright and copying permissions for this manual appear near the
beginning of indent.texinfo and indent.info, and near the
end of indent.1.
Copyright © 2015 Tim Hentenaar. Copyright © 2001 David Ingamells. Copyright © 1999 Carlo Wood. Copyright © 1995, 1996 Joseph Arceneaux. Copyright © 1989, 1992, 1993, 1994, 1995, 1996, 2014 Free Software Foundation Copyright © 1985 Sun Microsystems, Inc. Copyright © 1980 The Regents of the University of California. Copyright © 1976 Board of Trustees of the University of Illinois. All rights reserved. Redistribution and use in source and binary forms are permitted provided that the above copyright notice and this paragraph are duplicated in all such forms and that any documentation, advertising materials, and other materials related to such distribution and use acknowledge that the software was developed by the University of California, Berkeley, the University of Illinois, Urbana, and Sun Microsystems, Inc. The name of either University or Sun Microsystems may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED “AS IS” AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
Next: Index, Previous: Indent Program, Up: Top [Contents][Index]
Here is a list of all the options for indent
, alphabetized by
short option. It is followed by a cross key alphabetized by long option.
If using tabs for indentation, use spaces for alignment.
See Indentation.
Force blank lines after the declarations.
See Blank lines.
Force blank lines after procedure bodies.
See Blank lines.
Force blank lines before block comments.
See Blank lines.
Prefer to break long lines before boolean operators.
See Breaking long lines.
Force newline after comma in declaration.
See Declarations.
Put braces on line after if
, etc.
See Statements.
Put braces on line following function definition line.
See Declarations.
Indent braces n spaces.
See Statements.
Put braces on the line after struct
declaration lines.
See Declarations.
Put braces on line with if
, etc.
See Statements.
Put braces on function definition line.
See Declarations.
Put braces on struct
declaration line.
See Declarations.
Put a space between sizeof
and its argument.
See Statements.
Put comments to the right of code in column n.
See Comments.
Indent braces after a case label N spaces.
See Statements.
Put comments to the right of the declarations in column n.
See Comments.
Put comment delimiters on blank lines.
See Comments.
Cuddle while of do {} while;
and preceding ‘}’.
See Comments.
Cuddle else and preceding ‘}’.
See Comments.
Continuation indent of n spaces.
See Statements.
Case label indent of n spaces.
See Statements.
Put comments to the right of #else
and
#endif
statements in column n.
See Comments.
Put a space after a cast operator.
See Statements.
Set indentation of comments not to the right
of code to n spaces.
See Comments.
Break the line before all arguments in a declaration.
See Declarations.
Break the line after the last argument in a declaration.
See Declarations.
If -cd 0 is used then comments after declarations are left justified
behind the declaration.
See Declarations.
Put variables in column n.
See Declarations.
Format comments in the first column.
See Comments.
Do not disable all formatting of comments.
See Comments.
Fix nested comments.
See Comments.
Use GNU coding style. This is the default.
See Common styles.
Treat gettext _("...")
and N_("...")
as strings rather than as functions.
See Breaking long lines.
Prefer to break long lines at the position of newlines in the input.
See Breaking long lines.
Set indentation level to n spaces.
See Indentation.
Set offset for labels to column n.
See Indentation.
Indent parameter types in old-style function
definitions by n spaces.
See Indentation.
Use Kernighan & Ritchie coding style.
See Common styles.
Set maximum line length for non-comment lines to n.
See Breaking long lines.
Set maximum line length for comment formatting to n.
See Comments.
Use Linux coding style.
See Common styles.
Line up continued lines at parentheses.
See Indentation.
Leave space between ‘#’ and preprocessor directive.
See Indentation.
Remove space between ‘#’ and preprocessor directive.
See Indentation.
Do not force blank lines after declarations.
See Blank lines.
Do not force blank lines after procedure bodies.
See Blank lines.
Do not prefer to break long lines before boolean operators.
See Breaking long lines.
Do not force newlines after commas in declarations.
See Declarations.
Don’t put each argument in a function declaration on a separate line.
See Declarations.
Do not put comment delimiters on blank lines.
See Comments.
Do not cuddle }
and the while
of a do {} while;
.
See Statements.
Do not cuddle }
and else
.
See Statements.
Do not put a space after cast operators.
See Statements.
Comments after declarations are treated the same as
comments after other statements.
See Declarations.
Do not format comments in the first column as normal.
See Comments.
Do not format any comments.
See Comments.
Treat gettext _("...")
and N_("...")
as normal functions. This is the default.
See Breaking long lines.
Do not prefer to break long lines at the position of newlines in the input.
See Breaking long lines.
Zero width indentation for parameters.
See Indentation.
Do not line up parentheses.
See Statements.
Do not put space after the function in function calls.
See Statements.
Do not put a space after every ’(’ and before every ’)’.
See Statements.
Put the type of a procedure on the same line as its name.
See Declarations.
Do not put a space after every for
.
See Statements.
Do not put a space after every if
.
See Statements.
Do not put a space after every while
.
See Statements.
Do not put the ‘*’ character at the left of comments.
See Comments.
Do not swallow optional blank lines.
See Blank lines.
Do not force a space before the semicolon after certain statements.
Disables -ss.
See Statements.
Do not pad comments out to the nearest tabstop.
See Comments.
Use spaces instead of tabs.
See Indentation.
Disable verbose mode.
See Miscellaneous options.
Use the original Berkeley coding style.
See Common styles.
Do not read .indent.pro files.
See Invoking indent.
Put asterisks in pointer declarations on the left of spaces, next to types: “char* p”.
Put asterisks in pointer declarations on the right of spaces, next to variable names: “char *p”. This is the default behavior.
Insert a space between the name of the
procedure being called and the ‘(’.
See Statements.
Specify the extra indentation per open parentheses ’(’ when a statement is broken. See Statements.
Preserve access and modification times on output files. See Miscellaneous options.
Specify the indentation for preprocessor conditional statements. See Indentation.
Put a space after every ’(’ and before every ’)’.
See Statements.
Put the type of a procedure on the line before its name.
See Declarations.
Put a space after each for
.
See Statements.
Put a space after each if
.
See Statements.
Put a space after the ‘{’ and before the ‘}’ in initializers.
See Declarations.
Put a space after each while
.
See Statements.
Indent braces of a struct, union or enum N spaces.
See Statements.
Put the ‘*’ character at the left of comments.
See Comments.
Allow for unbraced conditionals (if
, else
, etc.) to have
their inner statement on the same line.
See Statements.
Swallow optional blank lines.
See Blank lines.
On one-line for
and while
statements,
force a blank before the semicolon.
See Statements.
Write to standard output.
See Invoking indent.
Tell indent
the name of typenames.
See Declarations.
Set tab size to n spaces.
See Indentation.
Use tabs. This is the default.
See Indentation.
Enable verbose mode.
See Miscellaneous options.
Output the version number of indent
.
See Miscellaneous options.
Here is a list of options alphabetized by long option, to help you find the corresponding short option.
--align-with-spaces -as --blank-lines-after-commas -bc --blank-lines-after-declarations -bad --blank-lines-after-procedures -bap --blank-lines-before-block-comments -bbb --braces-after-if-line -bl --braces-after-func-def-line -blf --brace-indent -bli --braces-after-struct-decl-line -bls --braces-on-if-line -br --braces-on-func-def-line -brf --braces-on-struct-decl-line -brs --break-after-boolean-operator -nbbo --break-before-boolean-operator -bbo --break-function-decl-args -bfda --break-function-decl-args-end -bfde --case-indentation -clin --case-brace-indentation -cbin --comment-delimiters-on-blank-lines -cdb --comment-indentation -cn --continuation-indentation -cin --continue-at-parentheses -lp --cuddle-do-while -cdw --cuddle-else -ce --declaration-comment-column -cdn --declaration-indentation -din --dont-break-function-decl-args -nbfda --dont-break-function-decl-args-end -nbfde --dont-break-procedure-type -npsl --dont-cuddle-do-while -ncdw --dont-cuddle-else -nce --dont-format-comments -nfca --dont-format-first-column-comments -nfc1 --dont-line-up-parentheses -nlp --dont-left-justify-declarations -ndj --dont-space-special-semicolon -nss --dont-star-comments -nsc --dont-tab-align-comments -ntac --else-endif-column -cpn --format-all-comments -fca --format-first-column-comments -fc1 --gnu-style -gnu --honour-newlines -hnl --ignore-newlines -nhnl --ignore-profile -npro --indent-label -iln --indent-level -in --k-and-r-style -kr --leave-optional-blank-lines -nsob --leave-preprocessor-space -lps --left-justify-declarations -dj --line-comments-indentation -dn --line-length -ln --linux-style -linux --no-blank-lines-after-commas -nbc --no-blank-lines-after-declarations -nbad --no-blank-lines-after-procedures -nbap --no-blank-lines-before-block-comments -nbbb --no-comment-delimiters-on-blank-lines -ncdb --no-space-after-casts -ncs --no-parameter-indentation -nip --no-space-after-for -nsaf --no-space-after-function-call-names -npcs --no-space-after-if -nsai --no-space-after-parentheses -nprs --no-space-after-while -nsaw --no-tabs -nut --no-verbosity -nv --original -orig --parameter-indentation -ipn --paren-indentation -pin --preserve-mtime -pmt --preprocessor-indentation -ppin --procnames-start-lines -psl --remove-preprocessor-space -nlps --single-line-conditionals -slc --space-after-cast -cs --space-after-for -saf --space-after-if -sai --space-after-parentheses -prs --space-after-procedure-calls -pcs --space-after-while -saw --space-special-semicolon -ss --spaces-around-initializers -sar --standard-output -st --start-left-side-of-comments -sc --struct-brace-indentation -sbin --swallow-optional-blank-lines -sob --tab-size -tsn --use-tabs -ut --verbose -v
Previous: Option Summary, Up: Top [Contents][Index]
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