Thread: get dimension of a table in c program from bash script

You likely will need to learn how to use dynamic memory management; but, this is just a guess based on the little information that you posted.
If you mean to recompile the program after each change then you could just change a header with the define by using a bash script.

Tim S.

Don't recompile the C program for every invocation!
Instead, pass the size as a command-line argument and dynamically allocate the memory.
In the bash script, if you wanted a dimension of 100 you would call the program like this:

Code:

program_name 100

Code:

#include <stdio.h>
#include <stdlib.h>
 
#define MAX_DIMENSION 1000
 
void use_a(int *a, int n)
{
    for (int i = 0; i < n; ++i) a[i] = i;
    for (int i = 0; i < n; ++i) printf("%d ", a[i]);
    putchar('\n');
}
  
int main(int argc, char **argv)
{
    if (argc != 2)
    {
        fprintf(stderr, "Usage: %s DIMENSION\n", argv[0]);
        exit(EXIT_FAILURE);
    }
 
    int n = atoi(argv[1]);
 
    if (n < 1 || n > MAX_DIMENSION)
    {
        fprintf(stderr, "Error: bad dimension: %d\n", n);
        exit(EXIT_FAILURE);
    }
 
    int *a = malloc(n * sizeof *a);
    if (!a)
    {
        perror("Error: malloc");
        exit(EXIT_FAILURE);
    }
 
    use_a(a, n);
 
    free(a);
 
    return 0;
}

Example bash script:

Code:

#!/bin/bash
 
N=(5 10 15 20)
 
for n in ${N[*]}; do
    ./myprog $n
done

Output:

Code:

0 1 2 3 4 
0 1 2 3 4 5 6 7 8 9 
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19