Question

How to use function pointer in struct to calculate factorial with C

Answer 1

#include <stdio.h>

typedef struct {
    int n;
    int (*funcPtr)(int);
} functionPointer;

int factorial(int num) {
    if (num == 0 || num == 1)
        return 1;
    else
        return num * factorial(num - 1);
}

int main()
{
    functionPointer fp;

    fp = (functionPointer) { .n = 5, .funcPtr = &factorial };
    
    printf("Factorial of %d = %d\n", fp.n, fp.funcPtr(fp.n));

    return 0;
}



/*
run:

Factorial of 5 = 120

*/

 

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Answer 2

#include <stdio.h>

typedef struct {
    int n;
    int (*funcPtr)(int);
} functionPointer;

int factorial(int num) {
    if (num == 0 || num == 1)
        return 1;
    else
        return num * factorial(num - 1);
}

int main()
{
    functionPointer fp = { .n = 6, .funcPtr = &factorial };
        
    printf("Factorial of %d = %d\n", fp.n, fp.funcPtr(fp.n));

    return 0;
}



/*
run:

Factorial of 6 = 720

*/

 

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