ref: ff2ebe6cfdacd890a74a6d2f9b0acd062d2633b7
dir: /sys/man/2/arg/
.TH ARG 2 .SH NAME ARGBEGIN, ARGEND, ARGC, ARGF, EARGF \- process option letters from argv .SH SYNOPSIS .B #include <u.h> .br .B #include <libc.h> .PP .nf .B ARGBEGIN { .B char *ARGF(); .B char *EARGF(code); .B Rune ARGC(); .B } ARGEND .PP .B extern char *argv0; .SH DESCRIPTION These macros assume the names .I argc and .I argv are in scope; see .IR exec (2). .I ARGBEGIN and .I ARGEND surround code for processing program options. The code should be the cases of a C switch on option characters; it is executed once for each option character. Options end after an argument .BR -- , before an argument .BR - , or before an argument that doesn't begin with .BR - . .PP The function macro .I ARGC returns the current option character, as an integer. .PP The function macro .I ARGF returns the current option argument: a pointer to the rest of the option string if not empty, or the next argument in .I argv if any, or 0. .I ARGF must be called just once for each option argument. The macro .I EARGF is like .I ARGF but instead of returning zero runs .I code and, if that returns, calls .IR abort (2). A typical value for .I code is .BR usage() , as in .BR EARGF(usage()) . .PP After .IR ARGBEGIN , .I argv0 is a copy of .BR argv[0] (conventionally the name of the program). .PP After .IR ARGEND , .I argv points at a zero-terminated list of the remaining .I argc arguments. .SH EXAMPLE This C program can take option .B b and option .BR f , which requires an argument. .IP .EX .ta \w'12345678'u +\w'12345678'u +\w'12345678'u +\w'12345678'u +\w'12345678'u #include <u.h> #include <libc.h> void main(int argc, char *argv[]) { char *f; print("%s", argv[0]); ARGBEGIN { case 'b': print(" -b"); break; case 'f': print(" -f(%s)", (f=ARGF())? f: "no arg"); break; default: print(" badflag('%c')", ARGC()); } ARGEND print(" %d args:", argc); while(*argv) print(" '%s'", *argv++); print("\en"); exits(nil); } .EE .PP Here is the output from running the command .B prog -bffile1 -r -f file2 arg1 arg2 .IP .B prog -b -f(file1) badflag('r') -f(file2) 2 args: 'arg1' 'arg2' .PP .SH SOURCE .B /sys/include/libc.h .SH SEE ALSO .IR getflags (8)