# <getopt.h>

**[<getopt.h>](https://en.cppreference.com/w/c/header/getopt)** (POSIX/GNU) provides `getopt` for short options (`-v`, `-o file`) and `getopt_long` for long options (`--verbose`, `--output=file`). It handles argument parsing, `optarg` tracking, and stops at the first non-option argument or `--`.

Use it to parse command-line arguments portably instead of handling `argv` manually.

## Example

This example parses both short and long options, handling argument requirements.

```c
// compile: gcc -o getoptexample getoptexample.c
// run: ./getoptexample -v --output=out.txt file1.txt
// description: parse short and long options with arguments

#include <getopt.h>
#include <stdio.h>

int main(int argc, char* argv[]) {
    int verbose = 0;
    const char* outfile = "a.out";
    int c;
    
    struct option opts[] = {
        {"verbose", no_argument, NULL, 'v'},
        {"output", required_argument, NULL, 'o'},
        {0, 0, 0, 0}
    };
    
    while ((c = getopt_long(argc, argv, "vo:", opts, NULL)) != -1) {
        switch (c) {
        case 'v': verbose = 1; break;
        case 'o': outfile = optarg; break;
        case '?': return 1;
        }
    }
    
    printf("verbose=%d output=%s\n", verbose, outfile);
    for (int i = optind; i < argc; i++)
        printf("  input: %s\n", argv[i]);
    
    return 0;
}
```