Pass arguments into C program from command line

Question

So I'm in Linux and I want to have a program accept arguments when you execute it from the command line.

For example,

./myprogram 42 -b -s

So then the program would store that number 42 as an int and execute certain parts of code depending on what arguments it gets like -b or -s.

Answer 1

You could use getopt.

 #include <ctype.h>  #include <stdio.h>  #include <stdlib.h>  #include <unistd.h>   int  main (int argc, char **argv)  {    int bflag = 0;    int sflag = 0;    int index;    int c;     opterr = 0;     while ((c = getopt (argc, argv, "bs")) != -1)      switch (c)        {        case 'b':          bflag = 1;          break;        case 's':          sflag = 1;          break;        case '?':          if (isprint (optopt))            fprintf (stderr, "Unknown option `-%c'.\n", optopt);          else            fprintf (stderr,                     "Unknown option character `\\x%x'.\n",                     optopt);          return 1;        default:          abort ();        }     printf ("bflag = %d, sflag = %d\n", bflag, sflag);     for (index = optind; index < argc; index++)      printf ("Non-option argument %s\n", argv[index]);    return 0;  } 

Answer 2

In C, this is done using arguments passed to your main() function:

int main(int argc, char *argv[]) {     int i = 0;     for (i = 0; i < argc; i++) {         printf("argv[%d] = %s\n", i, argv[i]);     }     return 0; } 

More information can be found online such as this Arguments to main article.