CAdvanced

C Pointers

Understand pointers in C: read a value through a pointer, modify memory by reference, and swap two variables using pointers.

01Pointer basics

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main.c

#include <stdio.h>

int main() {
    int x = 42;
    int *p = &x;
    printf("%d\n", *p);
    return 0;
}

Output

02Modify through a pointer

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main.c

#include <stdio.h>

int main() {
    int x = 10;
    int *p = &x;
    *p = 99;
    printf("%d\n", x);
    return 0;
}

Output

03Swap with pointers

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main.c

#include <stdio.h>

void swap(int *a, int *b) {
    int t = *a;
    *a = *b;
    *b = t;
}

int main() {
    int x = 1, y = 2;
    swap(&x, &y);
    printf("%d %d\n", x, y);
    return 0;
}

Output

2 1