map.c

#include <stdio.h>
#include <stdlib.h>
 
int square(int x){ 
    return x * x;
}
 
int *map(int array[], int size, int (*f)(int)){
    int i;
    int *out = calloc(size, sizeof(int));
    for(i=0; i<size; i++){
        // In this example I'm using map to give back an array of
        // the values squared. therefore you could view (f)(array[i])
        // as (squared)(array[i]) or squared(array[i])
        out[i] = (f)(array[i]);
    }   
    return out;
}
 
int main() {
    int array[3] = {1, 2, 3}; 
    int array_size = sizeof(array)/sizeof(int);
    int *mapped_array = map(array, array_size, square);
    int i;
    for(i=0; i<array_size; i++){
        printf("%d = %d\n", i, mapped_array[i]);
    }
    // Because I've allocated some memory for the mapped array I must free it.
    free(mapped_array);
    return 0;
}