Extending arvg[]

[mxs]

My question is how can I extend my argv from inside main so that if a user provides file xx the progam behaves as if it provided two xx input files?


example:

./run xx

// I have 

argv[0] = ./run
argv[1] = xx

/but now I wish to have behaviour as if i have executed:

./run xx xx

argv[0] = ./run
argv[1] = xx
argv[2] = xx

any advice ??

int main (int argc, char*argv[]){

   char **p = argv;
    argc = 0;
    while (*p++ != NULL) {
        argc++;
    }

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

[john.c]

You can't extend argv itself, but you can copy it's pointers to another char** and extend that.

BTW, what you're doing with argc makes no sense. You're just setting it back to the value it already had.

#include <stdio.h>
#include <stdlib.h>

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

int main (int argc, char **argv) {
    int ext_argc = argc + 1;
    char **ext_argv = malloc((ext_argc + 1) * sizeof *ext_argv); // +1 for NULL

    for (int i = 0; i < argc; i++)
        ext_argv[i] = argv[i];
    ext_argv[argc] = argv[argc - 1];
    ext_argv[ext_argc] = NULL;

    init(ext_argc, ext_argv);

    return 0;
}