51 lines
1.6 KiB
C
51 lines
1.6 KiB
C
/*
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* arg - A simple C program by Bruce Hill for parsing command line arguments
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* Licensed under the MIT license (see LICENSE for details).
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*
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* Example: arg --foo a b --foo=blah --baz -xyz
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* - Prints "blah" and exits with success
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* Example: arg --nope a b --foo=blah --baz -xyz
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* - Prints nothing and exits with failure
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* Example: arg -y a b --foo=blah --baz -xyz
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* - Prints nothing and exits with success
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*/
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#include <stdio.h>
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#include <string.h>
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const int EXIT_SUCCESS = 0;
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const int EXIT_NO_MATCH = 1;
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const int EXIT_BAD_USAGE = -1;
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int main(int argc, char **argv)
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{
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char *flag = argv[1];
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if (!flag) {
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fprintf(stderr, "Usage: arg <flag> ...\n");
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return EXIT_BAD_USAGE;
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}
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size_t flaglen = strlen(flag);
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int ischarflag = flag[0] == '-' && flaglen == 2;
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for (int i = 2; i < argc; i++) {
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char *arg = argv[i];
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if (strncmp(arg, flag, flaglen) == 0) {
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if (arg[flaglen] == '\0') { // --flag ...
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if (argv[i+1] && argv[i+1][0] != '-') // --flag <value>
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puts(argv[i+1]); // value of the flag
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return EXIT_SUCCESS;
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} else if (arg[flaglen] == '=') { // --flag=<value>
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puts(&arg[flaglen+1]);
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return EXIT_SUCCESS;
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}
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}
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if (ischarflag && arg[0] == '-' && arg[1] != '-') {
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// If flag is single-character, e.g. -f, look for it among other
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// single character flags like -xfy.
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for (char *c = &arg[1]; *c; c++) {
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if (*c == flag[1])
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return EXIT_SUCCESS;
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}
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}
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}
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return EXIT_NO_MATCH;
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}
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