Function Pointer Example

1Learning Outcomes¶

Trace an example involving function pointers.
Declare and initialize function pointers, and call functions pointed to by function pointers.

🎥 Lecture Video

2Example Code and Output¶

This program implements mutate_map, which maps a given function onto each element of an int array. Notably, mutate_map defines a function pointer parameter.

Example program map_func.c

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#include <stdio.h>

/* map function onto int array */
void mutate_map(int arr[], int n, int(*fp)(int)) {
    for (int i = 0; i < n; i++)  
        arr[i] = (*fp)(arr[i]);
}

/* prints int arrays */
void print_array(int arr[], int n) {
    for (int i = 0; i < n; i++)  
        printf("%d ", arr[i]);
    printf("\n");
}

int multiply2 (int x) {  return  2 * x;    }
int multiply10(int x) {  return 10 * x;   }

int main() {
    int arr[] = {3,1,4}, n = sizeof(arr)/sizeof(arr[0]);
    print_array(arr, n);

    mutate_map (arr, n, &multiply2);
    print_array(arr, n);

    mutate_map (arr, n, &multiply10);
    print_array(arr, n);

    return 0;
}

When running the compiled map_func executable;

$ ./map_func
3 1 4 
6 2 8 
60 20 80

1Learning Outcomes¶

2Example Code and Output¶

3More soon!¶