pointer demo

p1.c

#include <stdio.h>
#include <math.h>

void f1(int *ptr, int n) {
    printf("f1\n");
    for (int i = 0; i < n; i++) {
        printf("%d ", ptr[i]);
    }
    printf("\n");
}

void f2(int *ptr, int n) {
    printf("f2\n");
    for (int i = 0; i < n; i++) {
        int v = ptr[i];
        ptr[i] = v*v;
    }
}

void f3(int *ptr, double *ptr2, int n) {
    printf("f3\n");
    for (int i = 0; i < n; i++) {
        int v = ptr[i];
        ptr2[i] = sqrt(sqrt(v));
    }
}

int main(int argc, char** argv) {
    const int n = 5;
    int a[n] = { 1, 2, 3, 4, 5 };
    f1(a,n);
    f2(a,n);
    for (int i = 0; i < n; i++) {
        printf("%d ", a[i]);
    }
    printf("\n");
    double b[n];
    f3(a,b,n);
    for (int i = 0; i < n; i++) {
        printf("%3.2f ", b[i]);
    }
    printf("\n");
    return 0;
}