Functions पास करना

#include <stdio.h>

int apply(int x, int (*f)(int)) {
    return f(x);
}

int square(int x) { return x * x; }

int main(void) {
    printf("%d\n", apply(6, square));
    return 0;
}

#include <stdio.h>

void run_twice(void (*action)(void)) {
    action();
    action();
}

void beep(void) { printf("beep\n"); }

int main(void) {
    run_twice(beep);
    return 0;
}

#include <stdio.h>

int combine(int a, int b, int (*op)(int, int)) {
    return op(a, b);
}

int add(int a, int b) { return a + b; }
int mul(int a, int b) { return a * b; }

int main(void) {
    printf("%d\n", combine(3, 4, add));
    printf("%d\n", combine(3, 4, mul));
    return 0;
}

#include <stdio.h>

void map(int *a, int n, int (*f)(int)) {
    for (int i = 0; i < n; i++) a[i] = f(a[i]);
}

int inc(int x) { return x + 1; }

int main(void) {
    int a[] = {1, 2, 3};
    map(a, 3, inc);
    for (int i = 0; i < 3; i++) printf("%d ", a[i]);
    printf("\n");
    return 0;
}

#include <stdio.h>

int count_if(int *a, int n, int (*pred)(int)) {
    int c = 0;
    for (int i = 0; i < n; i++) if (pred(a[i])) c++;
    return c;
}

int is_even(int x) { return x % 2 == 0; }

int main(void) {
    int a[] = {1,2,3,4,5,6};
    printf("%d\n", count_if(a, 6, is_even));
    return 0;
}

#include <stdio.h>

int reduce(int *a, int n, int init, int (*op)(int,int)) {
    int acc = init;
    for (int i = 0; i < n; i++) acc = op(acc, a[i]);
    return acc;
}

int add(int a, int b) { return a + b; }

int main(void) {
    int a[] = {1,2,3,4};
    printf("%d\n", reduce(a, 4, 0, add));
    return 0;
}

#include <stdio.h>

int max_by(int a, int b, int (*greater)(int,int)) {
    return greater(a, b) ? a : b;
}

int gt(int a, int b) { return a > b; }

int main(void) {
    printf("%d\n", max_by(3, 8, gt));
    return 0;
}

#include <stdio.h>

typedef int (*IntFn)(int);

int apply(int x, IntFn f) { return f(x); }

int neg(int x) { return -x; }

int main(void) {
    printf("%d\n", apply(5, neg));
    return 0;
}

#include <stdio.h>

int apply(int x, int (*f)(int)) {
    if (f == NULL) return x;
    return f(x);
}

int dbl(int x) { return x * 2; }

int main(void) {
    printf("%d\n", apply(9, NULL));
    printf("%d\n", apply(9, dbl));
    return 0;
}

#include <stdio.h>

void for_each(int *a, int n, void (*visit)(int)) {
    for (int i = 0; i < n; i++) visit(a[i]);
}

void show(int x) { printf("[%d]", x); }

int main(void) {
    int a[] = {7, 8, 9};
    for_each(a, 3, show);
    printf("\n");
    return 0;
}

#include <stdio.h>

int apply(int x, int (*f)(int)) { return f(x); }
int sq(int x) { return x * x; }
int cube(int x) { return x * x * x; }

int main(void) {
    int power = 3;
    int (*f)(int) = (power == 2) ? sq : cube;
    printf("%d\n", apply(2, f));
    return 0;
}