Command Line Flags in Cilk

Command-line flags are a common way to specify options for command-line programs. For example, in wc -l the -l is a command-line flag.

Cilk doesn’t have a built-in package for parsing command-line flags, so we’ll use a simple approach to parse arguments manually. Here’s an example implementation:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <cilk/cilk.h>

void print_usage() {
    printf("Usage: ./program [options]\n");
    printf("Options:\n");
    printf("  -word <string>  : a string (default: \"foo\")\n");
    printf("  -numb <int>     : an int (default: 42)\n");
    printf("  -fork           : a bool\n");
    printf("  -svar <string>  : a string var (default: \"bar\")\n");
}

int main(int argc, char *argv[]) {
    char *word = "foo";
    int numb = 42;
    bool fork = false;
    char *svar = "bar";

    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "-word") == 0 && i + 1 < argc) {
            word = argv[++i];
        } else if (strcmp(argv[i], "-numb") == 0 && i + 1 < argc) {
            numb = atoi(argv[++i]);
        } else if (strcmp(argv[i], "-fork") == 0) {
            fork = true;
        } else if (strcmp(argv[i], "-svar") == 0 && i + 1 < argc) {
            svar = argv[++i];
        } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
            print_usage();
            return 0;
        } else {
            printf("Unknown option: %s\n", argv[i]);
            print_usage();
            return 1;
        }
    }

    printf("word: %s\n", word);
    printf("numb: %d\n", numb);
    printf("fork: %s\n", fork ? "true" : "false");
    printf("svar: %s\n", svar);

    return 0;
}

To compile and run this Cilk program:

$ cilk++ -O3 command_line_flags.c -o command_line_flags
$ ./command_line_flags -word=opt -numb=7 -fork -svar=flag
word: opt
numb: 7
fork: true
svar: flag

Note that if you omit flags, they automatically take their default values:

$ ./command_line_flags -word=opt
word: opt
numb: 42
fork: false
svar: bar

You can also use the -h or --help flags to get the usage information:

$ ./command_line_flags -h
Usage: ./program [options]
Options:
  -word <string>  : a string (default: "foo")
  -numb <int>     : an int (default: 42)
  -fork           : a bool
  -svar <string>  : a string var (default: "bar")

This implementation provides a basic command-line flag parsing functionality in Cilk. It doesn’t have all the features of Go’s flag package, but it demonstrates how to handle command-line arguments in a C-based language like Cilk.

Remember that Cilk is an extension of C, so it doesn’t have built-in support for command-line parsing like Go does. In a real-world scenario, you might want to use a more robust command-line parsing library for C, such as getopt or argp, which can be used with Cilk programs.

Command Line Arguments in Cilk

Context in Cilk

Learn X By Example

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Command Line Flags in Cilk