1*usr_29.txt* For Vim version 7.3. Last change: 2008 Jun 28 2 3 VIM USER MANUAL - by Bram Moolenaar 4 5 Moving through programs 6 7 8The creator of Vim is a computer programmer. It's no surprise that Vim 9contains many features to aid in writing programs. Jump around to find where 10identifiers are defined and used. Preview declarations in a separate window. 11There is more in the next chapter. 12 13|29.1| Using tags 14|29.2| The preview window 15|29.3| Moving through a program 16|29.4| Finding global identifiers 17|29.5| Finding local identifiers 18 19 Next chapter: |usr_30.txt| Editing programs 20 Previous chapter: |usr_28.txt| Folding 21Table of contents: |usr_toc.txt| 22 23============================================================================== 24*29.1* Using tags 25 26What is a tag? It is a location where an identifier is defined. An example 27is a function definition in a C or C++ program. A list of tags is kept in a 28tags file. This can be used by Vim to directly jump from any place to the 29tag, the place where an identifier is defined. 30 To generate the tags file for all C files in the current directory, use the 31following command: > 32 33 ctags *.c 34 35"ctags" is a separate program. Most Unix systems already have it installed. 36If you do not have it yet, you can find Exuberant ctags here: 37 38 http://ctags.sf.net ~ 39 40Now when you are in Vim and you want to go to a function definition, you can 41jump to it by using the following command: > 42 43 :tag startlist 44 45This command will find the function "startlist" even if it is in another file. 46 The CTRL-] command jumps to the tag of the word that is under the cursor. 47This makes it easy to explore a tangle of C code. Suppose, for example, that 48you are in the function "write_block". You can see that it calls 49"write_line". But what does "write_line" do? By placing the cursor on the 50call to "write_line" and pressing CTRL-], you jump to the definition of this 51function. 52 The "write_line" function calls "write_char". You need to figure out what 53it does. So you position the cursor over the call to "write_char" and press 54CTRL-]. Now you are at the definition of "write_char". 55 56 +-------------------------------------+ 57 |void write_block(char **s; int cnt) | 58 |{ | 59 | int i; | 60 | for (i = 0; i < cnt; ++i) | 61 | write_line(s[i]); | 62 |} | | 63 +-----------|-------------------------+ 64 | 65 CTRL-] | 66 | +----------------------------+ 67 +--> |void write_line(char *s) | 68 |{ | 69 | while (*s != 0) | 70 | write_char(*s++); | 71 |} | | 72 +--------|-------------------+ 73 | 74 CTRL-] | 75 | +------------------------------------+ 76 +--> |void write_char(char c) | 77 |{ | 78 | putchar((int)(unsigned char)c); | 79 |} | 80 +------------------------------------+ 81 82The ":tags" command shows the list of tags that you traversed through: 83 84 :tags 85 # TO tag FROM line in file/text ~ 86 1 1 write_line 8 write_block.c ~ 87 2 1 write_char 7 write_line.c ~ 88 > ~ 89> 90Now to go back. The CTRL-T command goes to the preceding tag. In the example 91above you get back to the "write_line" function, in the call to "write_char". 92 This command takes a count argument that indicates how many tags to jump 93back. You have gone forward, and now back. Let's go forward again. The 94following command goes to the tag on top of the list: > 95 96 :tag 97 98You can prefix it with a count and jump forward that many tags. For example: 99":3tag". CTRL-T also can be preceded with a count. 100 These commands thus allow you to go down a call tree with CTRL-] and back 101up again with CTRL-T. Use ":tags" to find out where you are. 102 103 104SPLIT WINDOWS 105 106The ":tag" command replaces the file in the current window with the one 107containing the new function. But suppose you want to see not only the old 108function but also the new one? You can split the window using the ":split" 109command followed by the ":tag" command. Vim has a shorthand command that does 110both: > 111 :stag tagname 112 113To split the current window and jump to the tag under the cursor use this 114command: > 115 116 CTRL-W ] 117 118If a count is specified, the new window will be that many lines high. 119 120 121MORE TAGS FILES 122 123When you have files in many directories, you can create a tags file in each of 124them. Vim will then only be able to jump to tags within that directory. 125 To find more tags files, set the 'tags' option to include all the relevant 126tags files. Example: > 127 128 :set tags=./tags,./../tags,./*/tags 129 130This finds a tags file in the same directory as the current file, one 131directory level higher and in all subdirectories. 132 This is quite a number of tags files, but it may still not be enough. For 133example, when editing a file in "~/proj/src", you will not find the tags file 134"~/proj/sub/tags". For this situation Vim offers to search a whole directory 135tree for tags files. Example: > 136 137 :set tags=~/proj/**/tags 138 139 140ONE TAGS FILE 141 142When Vim has to search many places for tags files, you can hear the disk 143rattling. It may get a bit slow. In that case it's better to spend this 144time while generating one big tags file. You might do this overnight. 145 This requires the Exuberant ctags program, mentioned above. It offers an 146argument to search a whole directory tree: > 147 148 cd ~/proj 149 ctags -R . 150 151The nice thing about this is that Exuberant ctags recognizes various file 152types. Thus this doesn't work just for C and C++ programs, also for Eiffel 153and even Vim scripts. See the ctags documentation to tune this. 154 Now you only need to tell Vim where your big tags file is: > 155 156 :set tags=~/proj/tags 157 158 159MULTIPLE MATCHES 160 161When a function is defined multiple times (or a method in several classes), 162the ":tag" command will jump to the first one. If there is a match in the 163current file, that one is used first. 164 You can now jump to other matches for the same tag with: > 165 166 :tnext 167 168Repeat this to find further matches. If there are many, you can select which 169one to jump to: > 170 171 :tselect tagname 172 173Vim will present you with a list of choices: 174 175 # pri kind tag file ~ 176 1 F f mch_init os_amiga.c ~ 177 mch_init() ~ 178 2 F f mch_init os_mac.c ~ 179 mch_init() ~ 180 3 F f mch_init os_msdos.c ~ 181 mch_init(void) ~ 182 4 F f mch_init os_riscos.c ~ 183 mch_init() ~ 184 Enter nr of choice (<CR> to abort): ~ 185 186You can now enter the number (in the first column) of the match that you would 187like to jump to. The information in the other columns give you a good idea of 188where the match is defined. 189 190To move between the matching tags, these commands can be used: 191 192 :tfirst go to first match 193 :[count]tprevious go to [count] previous match 194 :[count]tnext go to [count] next match 195 :tlast go to last match 196 197If [count] is omitted then one is used. 198 199 200GUESSING TAG NAMES 201 202Command line completion is a good way to avoid typing a long tag name. Just 203type the first bit and press <Tab>: > 204 205 :tag write_<Tab> 206 207You will get the first match. If it's not the one you want, press <Tab> until 208you find the right one. 209 Sometimes you only know part of the name of a function. Or you have many 210tags that start with the same string, but end differently. Then you can tell 211Vim to use a pattern to find the tag. 212 Suppose you want to jump to a tag that contains "block". First type 213this: > 214 215 :tag /block 216 217Now use command line completion: press <Tab>. Vim will find all tags that 218contain "block" and use the first match. 219 The "/" before a tag name tells Vim that what follows is not a literal tag 220name, but a pattern. You can use all the items for search patterns here. For 221example, suppose you want to select a tag that starts with "write_": > 222 223 :tselect /^write_ 224 225The "^" specifies that the tag starts with "write_". Otherwise it would also 226be found halfway a tag name. Similarly "$" at the end makes sure the pattern 227matches until the end of a tag. 228 229 230A TAGS BROWSER 231 232Since CTRL-] takes you to the definition of the identifier under the cursor, 233you can use a list of identifier names as a table of contents. Here is an 234example. 235 First create a list of identifiers (this requires Exuberant ctags): > 236 237 ctags --c-types=f -f functions *.c 238 239Now start Vim without a file, and edit this file in Vim, in a vertically split 240window: > 241 242 vim 243 :vsplit functions 244 245The window contains a list of all the functions. There is some more stuff, 246but you can ignore that. Do ":setlocal ts=99" to clean it up a bit. 247 In this window, define a mapping: > 248 249 :nnoremap <buffer> <CR> 0ye<C-W>w:tag <C-R>"<CR> 250 251Move the cursor to the line that contains the function you want to go to. 252Now press <Enter>. Vim will go to the other window and jump to the selected 253function. 254 255 256RELATED ITEMS 257 258You can set 'ignorecase' to make case in tag names be ignored. 259 260The 'tagbsearch' option tells if the tags file is sorted or not. The default 261is to assume a sorted tags file, which makes a tags search a lot faster, but 262doesn't work if the tags file isn't sorted. 263 264The 'taglength' option can be used to tell Vim the number of significant 265characters in a tag. 266 267When you use the SNiFF+ program, you can use the Vim interface to it |sniff|. 268SNiFF+ is a commercial program. 269 270Cscope is a free program. It does not only find places where an identifier is 271declared, but also where it is used. See |cscope|. 272 273============================================================================== 274*29.2* The preview window 275 276When you edit code that contains a function call, you need to use the correct 277arguments. To know what values to pass you can look at how the function is 278defined. The tags mechanism works very well for this. Preferably the 279definition is displayed in another window. For this the preview window can be 280used. 281 To open a preview window to display the function "write_char": > 282 283 :ptag write_char 284 285Vim will open a window, and jumps to the tag "write_char". Then it takes you 286back to the original position. Thus you can continue typing without the need 287to use a CTRL-W command. 288 If the name of a function appears in the text, you can get its definition 289in the preview window with: > 290 291 CTRL-W } 292 293There is a script that automatically displays the text where the word under 294the cursor was defined. See |CursorHold-example|. 295 296To close the preview window use this command: > 297 298 :pclose 299 300To edit a specific file in the preview window, use ":pedit". This can be 301useful to edit a header file, for example: > 302 303 :pedit defs.h 304 305Finally, ":psearch" can be used to find a word in the current file and any 306included files and display the match in the preview window. This is 307especially useful when using library functions, for which you do not have a 308tags file. Example: > 309 310 :psearch popen 311 312This will show the "stdio.h" file in the preview window, with the function 313prototype for popen(): 314 315 FILE *popen __P((const char *, const char *)); ~ 316 317You can specify the height of the preview window, when it is opened, with the 318'previewheight' option. 319 320============================================================================== 321*29.3* Moving through a program 322 323Since a program is structured, Vim can recognize items in it. Specific 324commands can be used to move around. 325 C programs often contain constructs like this: 326 327 #ifdef USE_POPEN ~ 328 fd = popen("ls", "r") ~ 329 #else ~ 330 fd = fopen("tmp", "w") ~ 331 #endif ~ 332 333But then much longer, and possibly nested. Position the cursor on the 334"#ifdef" and press %. Vim will jump to the "#else". Pressing % again takes 335you to the "#endif". Another % takes you to the "#ifdef" again. 336 When the construct is nested, Vim will find the matching items. This is a 337good way to check if you didn't forget an "#endif". 338 When you are somewhere inside a "#if" - "#endif", you can jump to the start 339of it with: > 340 341 [# 342 343If you are not after a "#if" or "#ifdef" Vim will beep. To jump forward to 344the next "#else" or "#endif" use: > 345 346 ]# 347 348These two commands skip any "#if" - "#endif" blocks that they encounter. 349Example: 350 351 #if defined(HAS_INC_H) ~ 352 a = a + inc(); ~ 353 # ifdef USE_THEME ~ 354 a += 3; ~ 355 # endif ~ 356 set_width(a); ~ 357 358With the cursor in the last line, "[#" moves to the first line. The "#ifdef" 359- "#endif" block in the middle is skipped. 360 361 362MOVING IN CODE BLOCKS 363 364In C code blocks are enclosed in {}. These can get pretty long. To move to 365the start of the outer block use the "[[" command. Use "][" to find the end. 366This assumes that the "{" and "}" are in the first column. 367 The "[{" command moves to the start of the current block. It skips over 368pairs of {} at the same level. "]}" jumps to the end. 369 An overview: 370 371 function(int a) 372 +-> { 373 | if (a) 374 | +-> { 375 [[ | | for (;;) --+ 376 | | +-> { | 377 | [{ | | foo(32); | --+ 378 | | [{ | if (bar(a)) --+ | ]} | 379 +-- | +-- break; | ]} | | 380 | } <-+ | | ][ 381 +-- foobar(a) | | 382 } <-+ | 383 } <-+ 384 385When writing C++ or Java, the outer {} block is for the class. The next level 386of {} is for a method. When somewhere inside a class use "[m" to find the 387previous start of a method. "]m" finds the next start of a method. 388 389Additionally, "[]" moves backward to the end of a function and "]]" moves 390forward to the start of the next function. The end of a function is defined 391by a "}" in the first column. 392 393 int func1(void) 394 { 395 return 1; 396 +----------> } 397 | 398 [] | int func2(void) 399 | +-> { 400 | [[ | if (flag) 401 start +-- +-- return flag; 402 | ][ | return 2; 403 | +-> } 404 ]] | 405 | int func3(void) 406 +----------> { 407 return 3; 408 } 409 410Don't forget you can also use "%" to move between matching (), {} and []. 411That also works when they are many lines apart. 412 413 414MOVING IN BRACES 415 416The "[(" and "])" commands work similar to "[{" and "]}", except that they 417work on () pairs instead of {} pairs. 418> 419 [( 420< <-------------------------------- 421 <------- 422 if (a == b && (c == d || (e > f)) && x > y) ~ 423 --------------> 424 --------------------------------> > 425 ]) 426 427MOVING IN COMMENTS 428 429To move back to the start of a comment use "[/". Move forward to the end of a 430comment with "]/". This only works for /* - */ comments. 431 432 +-> +-> /* 433 | [/ | * A comment about --+ 434 [/ | +-- * wonderful life. | ]/ 435 | */ <-+ 436 | 437 +-- foo = bar * 3; --+ 438 | ]/ 439 /* a short comment */ <-+ 440 441============================================================================== 442*29.4* Finding global identifiers 443 444You are editing a C program and wonder if a variable is declared as "int" or 445"unsigned". A quick way to find this is with the "[I" command. 446 Suppose the cursor is on the word "column". Type: > 447 448 [I 449 450Vim will list the matching lines it can find. Not only in the current file, 451but also in all included files (and files included in them, etc.). The result 452looks like this: 453 454 structs.h ~ 455 1: 29 unsigned column; /* column number */ ~ 456 457The advantage over using tags or the preview window is that included files are 458searched. In most cases this results in the right declaration to be found. 459Also when the tags file is out of date. Also when you don't have tags for the 460included files. 461 However, a few things must be right for "[I" to do its work. First of all, 462the 'include' option must specify how a file is included. The default value 463works for C and C++. For other languages you will have to change it. 464 465 466LOCATING INCLUDED FILES 467 468 Vim will find included files in the places specified with the 'path' 469option. If a directory is missing, some include files will not be found. You 470can discover this with this command: > 471 472 :checkpath 473 474It will list the include files that could not be found. Also files included 475by the files that could be found. An example of the output: 476 477 --- Included files not found in path --- ~ 478 <io.h> ~ 479 vim.h --> ~ 480 <functions.h> ~ 481 <clib/exec_protos.h> ~ 482 483The "io.h" file is included by the current file and can't be found. "vim.h" 484can be found, thus ":checkpath" goes into this file and checks what it 485includes. The "functions.h" and "clib/exec_protos.h" files, included by 486"vim.h" are not found. 487 488 Note: 489 Vim is not a compiler. It does not recognize "#ifdef" statements. 490 This means every "#include" statement is used, also when it comes 491 after "#if NEVER". 492 493To fix the files that could not be found, add a directory to the 'path' 494option. A good place to find out about this is the Makefile. Look out for 495lines that contain "-I" items, like "-I/usr/local/X11". To add this directory 496use: > 497 498 :set path+=/usr/local/X11 499 500When there are many subdirectories, you can use the "*" wildcard. Example: > 501 502 :set path+=/usr/*/include 503 504This would find files in "/usr/local/include" as well as "/usr/X11/include". 505 506When working on a project with a whole nested tree of included files, the "**" 507items is useful. This will search down in all subdirectories. Example: > 508 509 :set path+=/projects/invent/**/include 510 511This will find files in the directories: 512 513 /projects/invent/include ~ 514 /projects/invent/main/include ~ 515 /projects/invent/main/os/include ~ 516 etc. 517 518There are even more possibilities. Check out the 'path' option for info. 519 If you want to see which included files are actually found, use this 520command: > 521 522 :checkpath! 523 524You will get a (very long) list of included files, the files they include, and 525so on. To shorten the list a bit, Vim shows "(Already listed)" for files that 526were found before and doesn't list the included files in there again. 527 528 529JUMPING TO A MATCH 530 531"[I" produces a list with only one line of text. When you want to have a 532closer look at the first item, you can jump to that line with the command: > 533 534 [<Tab> 535 536You can also use "[ CTRL-I", since CTRL-I is the same as pressing <Tab>. 537 538The list that "[I" produces has a number at the start of each line. When you 539want to jump to another item than the first one, type the number first: > 540 541 3[<Tab> 542 543Will jump to the third item in the list. Remember that you can use CTRL-O to 544jump back to where you started from. 545 546 547RELATED COMMANDS 548 549 [i only lists the first match 550 ]I only lists items below the cursor 551 ]i only lists the first item below the cursor 552 553 554FINDING DEFINED IDENTIFIERS 555 556The "[I" command finds any identifier. To find only macros, defined with 557"#define" use: > 558 559 [D 560 561Again, this searches in included files. The 'define' option specifies what a 562line looks like that defines the items for "[D". You could change it to make 563it work with other languages than C or C++. 564 The commands related to "[D" are: 565 566 [d only lists the first match 567 ]D only lists items below the cursor 568 ]d only lists the first item below the cursor 569 570============================================================================== 571*29.5* Finding local identifiers 572 573The "[I" command searches included files. To search in the current file only, 574and jump to the first place where the word under the cursor is used: > 575 576 gD 577 578Hint: Goto Definition. This command is very useful to find a variable or 579function that was declared locally ("static", in C terms). Example (cursor on 580"counter"): 581 582 +-> static int counter = 0; 583 | 584 | int get_counter(void) 585 gD | { 586 | ++counter; 587 +-- return counter; 588 } 589 590To restrict the search even further, and look only in the current function, 591use this command: > 592 593 gd 594 595This will go back to the start of the current function and find the first 596occurrence of the word under the cursor. Actually, it searches backwards to 597an empty line above a "{" in the first column. From there it searches forward 598for the identifier. Example (cursor on "idx"): 599 600 int find_entry(char *name) 601 { 602 +-> int idx; 603 | 604 gd | for (idx = 0; idx < table_len; ++idx) 605 | if (strcmp(table[idx].name, name) == 0) 606 +-- return idx; 607 } 608 609============================================================================== 610 611Next chapter: |usr_30.txt| Editing programs 612 613Copyright: see |manual-copyright| vim:tw=78:ts=8:ft=help:norl: 614