kmj
06-19-2002, 02:11 PM
Introduction to Programming in C/C++ with Vim
Vi has been one of the most popular editing tools for programmers since Bill Joy first created it. Over the years it has evolved, and the current version of vim has many capabilities which make a programmer's life easy. Listed below is a brief description of some tools which have made so many programmers loyal to vi and vim. The purpose of this document is to inform propspective Vim users of, and introduce them to some of these tools, but not necessarily to be the definitive source of information on them. In most cases, interested readers should check the noted "extra information" sources.
Note: Throughout this paper, I may use the name vi when referring to vim. Some options may only be compatible with vim, and not vi.
On with the features:
Ctags
Ctags is a program that comes with vim. Basically, it's purpose is to help a programmer get to various parts of his program with relative ease. The typical method of running ctags is by simply typing the following in your source directory:
[/home/someuser/src]$ ctags *
This will create a 'tags' file in your current directory with the following information for all C or C++ files in you
directory. This file contains a listing of the following objects:
- macros defined by #define
- enumerated values
- function definitions, prototypes, and declarations
- class, enum, struct, and union names
- variables (definitions and declarations)
- class, struct, and union members
Vim then uses this file to help you locate these tagged items. This can be done in a few ways. First, one can open vim to the location of a tagged object. To do this, run vim with the '-t'
flag and the tag-name as an rgument. For example:
[/home/someuser/src]$ vi -t foo_bar
would open to the file containing the definition of foo_bar at that line. If you are already in vi, you can enter the command by the tag-name:
:ta foo_bar
This may take you out of the file you are currently in, unless the 'autowrite' option is enabled. (It is off by default.)
For more information on autowrite, type ':h autowrite' from with vi command-mode. The final way to jump to a tagged location is by typing Ctrl-] in command mode while the cursor is on a specific word. For example, if you are looking at my program, and you come across a point where I call foo_bar(), you can type 'Ctrl-]' while the cursor is somewhere on that word and it will jump to that definition. Note that 'Ctrl-]' is the escape character for telnet, so this may cause some issues if your editing files remotely. Type ':h ^]' for more information. Togo back to the point you were at before jumping to a ctag, simply type Ctr-t.
Ctags can also be used with other languages (java, fortran, ...and more) and editors (emacs, NEdit, ...and more). When set up properly, this tool can make your job tremendously easier, especially when you have to jump into a large ongoing project head-first.
For more information: View the man page, man ctags, or view the vim help, :h ctags.
Auto-Indenting
Vi has various methods of implementing auto-indenting. The best for C and C++ programmers is, obviously, cindent mode.
This is a very versatile tool which gives the programmer much control over
the look and feel of his source code, without any effort (except the effort
of initial setup, of course). To enable c-indenting, just type :set cindent' from the command mode. The most important thing to note is that cindenting makes use of shiftwidth, not tabstops. The default shiftwidth is 8. In order to change this, enter :set shiftwidth=x where x is the desired number of spaces to shift. The default cindent options tend to be nice, but if you find your program indenting in some way that is nnoying, you can modify the behaviour. To set the cindent options, type :set cino=<string>, where <string> is a list defining exactly how you want your cindent options to behave. There are quite a few different types of indenting which can be done, and vim's help does a good job explaining them, so I won't go over them here. To view the help for the possible values of cinoptions, type :h cinoptions-values. To view the current values, simply type ':set cino'. Most likely there will be none, since everything starts at a default value.
For more information, check out the following: ':h shiftwidth', :h cindent', ':h cinoptions', ':h cinoptions-values', ':h cinkeys', and ':h cinwords'.
Programmers who are used to integrated development environments know the beauty of syntax highlighting. It doesn't just make your code more readable; it also helps prevent annoying commenting
and string errors. Vim has syntax highlighting for a number of languages. To enable it, type ':syntax
on'. Using it is as simple as that if you're happy with the default values. Vim's syntax highlighting tools can be quite complex, with a number of different things to play around with. To view information on syntax hilighting, type ':h syntax', which will
lead you to vim's extensive help system. Syntax hilighting with color
terminals and with gvim is nice, but if you don't have color, vim uses
underlining, boldface, etc. To me, this is pretty ugly. For more info: ':h syntax', ':h syn-qstart', ':h syntax-printing'
QuickFix
This is a really nifty feature. Basically,
by typing one command, you can cause vim to attempt to make the program
you're working on, then open to whatever file first compiler error is in
at the line of that error. The command to execute is ':mak' (or ':make'). Vim will run whatever program is denoted
by the value of 'makeprg'. The default value for 'makeprg' is 'make'. You can change this, if you wish, by typing ':set makprg=<string>', where <string> denotes the desired command. Vim uses the 'errorformat' value to figure out how to understand the output from the compiler. Since different compilers have different output format's, you'll probably have to enter the format string. The method used
is rather similar to C-style formatting with scanf. The most important format specifiers are %f, meaning filename, %l, meaing line-number, and %m, meaning message. %f:%l:\%m
This can become quite complex with different compilers, but fortunately, vim has a world of information in their help at ':h errorformat'. For more info, check: 'h: quickfix', ':h mak', ':h makeprg', ':h errorfile', ':h
errorformat'.
Useful Keystrokes
There are certain command-mode keystrokes that are especially useful for programmers. Below is a small subset of these:
[[ = Go to previous first-column '{'; equivilent to ?^{
]] = Go to next first-column '{';
equivilent to /^{
[] = Go to previous first-column '}'; equivilient to ?^}
][ = Go to next first-column '}';
equivilent to /^}
{ = Go to previous blank line.
} = Go to next blank line.
gd = Go to definition
of current local variable (current = cursor is on it)
* = Go to next instance of current word
# = Go to previous instance of current word
'' = Go to location where last search was started.
Parenthesis Matching
% takes you to the matching parenthesis, curly brace, or bracket, depending on what you are on. This always comes in handy as a quick double-check.
Pattern matching and substitution
Vim has powerful substition
capabilities, with a very simple interface. No annoying GUI to get in the way (though you may need to keep a cheat-sheet handy). To
search for and replace text, use the following command:
: [address] s/<pattern>/<string>/[g|c|N]
This finds one (or more) instance
of the grep-style regular expression represented by <pattern>, and substitutes it with <string>. 'address', 'g', and 'N' are modifiers which
determine which and how many occurances of <pattern> are replaced.
g Global: Replace all occurances of <pattern> on the line.
c Cond: Ask before making each replacement.
N N represents an integer value. Replace only the Nth occurance of <pattern> on the line.
No modifier: implies N=1, the first occurance on that line
The [address] field may be one specifier or two seperated by a comma. (Below, x represents
an integer.)
. The current line
$ The last line in the file
% Entire file
x The xth line of the file
+x x lines after the current line
-x x lines before the current line
The comma may seperate any of the above in order to specify a range. All
lines within the given range will undergo the substitution. The best reference I have found for subsituting can be found at the Vi Helpfile, linked
below.
Vi has been one of the most popular editing tools for programmers since Bill Joy first created it. Over the years it has evolved, and the current version of vim has many capabilities which make a programmer's life easy. Listed below is a brief description of some tools which have made so many programmers loyal to vi and vim. The purpose of this document is to inform propspective Vim users of, and introduce them to some of these tools, but not necessarily to be the definitive source of information on them. In most cases, interested readers should check the noted "extra information" sources.
Note: Throughout this paper, I may use the name vi when referring to vim. Some options may only be compatible with vim, and not vi.
On with the features:
Ctags
Ctags is a program that comes with vim. Basically, it's purpose is to help a programmer get to various parts of his program with relative ease. The typical method of running ctags is by simply typing the following in your source directory:
[/home/someuser/src]$ ctags *
This will create a 'tags' file in your current directory with the following information for all C or C++ files in you
directory. This file contains a listing of the following objects:
- macros defined by #define
- enumerated values
- function definitions, prototypes, and declarations
- class, enum, struct, and union names
- variables (definitions and declarations)
- class, struct, and union members
Vim then uses this file to help you locate these tagged items. This can be done in a few ways. First, one can open vim to the location of a tagged object. To do this, run vim with the '-t'
flag and the tag-name as an rgument. For example:
[/home/someuser/src]$ vi -t foo_bar
would open to the file containing the definition of foo_bar at that line. If you are already in vi, you can enter the command by the tag-name:
:ta foo_bar
This may take you out of the file you are currently in, unless the 'autowrite' option is enabled. (It is off by default.)
For more information on autowrite, type ':h autowrite' from with vi command-mode. The final way to jump to a tagged location is by typing Ctrl-] in command mode while the cursor is on a specific word. For example, if you are looking at my program, and you come across a point where I call foo_bar(), you can type 'Ctrl-]' while the cursor is somewhere on that word and it will jump to that definition. Note that 'Ctrl-]' is the escape character for telnet, so this may cause some issues if your editing files remotely. Type ':h ^]' for more information. Togo back to the point you were at before jumping to a ctag, simply type Ctr-t.
Ctags can also be used with other languages (java, fortran, ...and more) and editors (emacs, NEdit, ...and more). When set up properly, this tool can make your job tremendously easier, especially when you have to jump into a large ongoing project head-first.
For more information: View the man page, man ctags, or view the vim help, :h ctags.
Auto-Indenting
Vi has various methods of implementing auto-indenting. The best for C and C++ programmers is, obviously, cindent mode.
This is a very versatile tool which gives the programmer much control over
the look and feel of his source code, without any effort (except the effort
of initial setup, of course). To enable c-indenting, just type :set cindent' from the command mode. The most important thing to note is that cindenting makes use of shiftwidth, not tabstops. The default shiftwidth is 8. In order to change this, enter :set shiftwidth=x where x is the desired number of spaces to shift. The default cindent options tend to be nice, but if you find your program indenting in some way that is nnoying, you can modify the behaviour. To set the cindent options, type :set cino=<string>, where <string> is a list defining exactly how you want your cindent options to behave. There are quite a few different types of indenting which can be done, and vim's help does a good job explaining them, so I won't go over them here. To view the help for the possible values of cinoptions, type :h cinoptions-values. To view the current values, simply type ':set cino'. Most likely there will be none, since everything starts at a default value.
For more information, check out the following: ':h shiftwidth', :h cindent', ':h cinoptions', ':h cinoptions-values', ':h cinkeys', and ':h cinwords'.
Programmers who are used to integrated development environments know the beauty of syntax highlighting. It doesn't just make your code more readable; it also helps prevent annoying commenting
and string errors. Vim has syntax highlighting for a number of languages. To enable it, type ':syntax
on'. Using it is as simple as that if you're happy with the default values. Vim's syntax highlighting tools can be quite complex, with a number of different things to play around with. To view information on syntax hilighting, type ':h syntax', which will
lead you to vim's extensive help system. Syntax hilighting with color
terminals and with gvim is nice, but if you don't have color, vim uses
underlining, boldface, etc. To me, this is pretty ugly. For more info: ':h syntax', ':h syn-qstart', ':h syntax-printing'
QuickFix
This is a really nifty feature. Basically,
by typing one command, you can cause vim to attempt to make the program
you're working on, then open to whatever file first compiler error is in
at the line of that error. The command to execute is ':mak' (or ':make'). Vim will run whatever program is denoted
by the value of 'makeprg'. The default value for 'makeprg' is 'make'. You can change this, if you wish, by typing ':set makprg=<string>', where <string> denotes the desired command. Vim uses the 'errorformat' value to figure out how to understand the output from the compiler. Since different compilers have different output format's, you'll probably have to enter the format string. The method used
is rather similar to C-style formatting with scanf. The most important format specifiers are %f, meaning filename, %l, meaing line-number, and %m, meaning message. %f:%l:\%m
This can become quite complex with different compilers, but fortunately, vim has a world of information in their help at ':h errorformat'. For more info, check: 'h: quickfix', ':h mak', ':h makeprg', ':h errorfile', ':h
errorformat'.
Useful Keystrokes
There are certain command-mode keystrokes that are especially useful for programmers. Below is a small subset of these:
[[ = Go to previous first-column '{'; equivilent to ?^{
]] = Go to next first-column '{';
equivilent to /^{
[] = Go to previous first-column '}'; equivilient to ?^}
][ = Go to next first-column '}';
equivilent to /^}
{ = Go to previous blank line.
} = Go to next blank line.
gd = Go to definition
of current local variable (current = cursor is on it)
* = Go to next instance of current word
# = Go to previous instance of current word
'' = Go to location where last search was started.
Parenthesis Matching
% takes you to the matching parenthesis, curly brace, or bracket, depending on what you are on. This always comes in handy as a quick double-check.
Pattern matching and substitution
Vim has powerful substition
capabilities, with a very simple interface. No annoying GUI to get in the way (though you may need to keep a cheat-sheet handy). To
search for and replace text, use the following command:
: [address] s/<pattern>/<string>/[g|c|N]
This finds one (or more) instance
of the grep-style regular expression represented by <pattern>, and substitutes it with <string>. 'address', 'g', and 'N' are modifiers which
determine which and how many occurances of <pattern> are replaced.
g Global: Replace all occurances of <pattern> on the line.
c Cond: Ask before making each replacement.
N N represents an integer value. Replace only the Nth occurance of <pattern> on the line.
No modifier: implies N=1, the first occurance on that line
The [address] field may be one specifier or two seperated by a comma. (Below, x represents
an integer.)
. The current line
$ The last line in the file
% Entire file
x The xth line of the file
+x x lines after the current line
-x x lines before the current line
The comma may seperate any of the above in order to specify a range. All
lines within the given range will undergo the substitution. The best reference I have found for subsituting can be found at the Vi Helpfile, linked
below.