code

#include<stdio.h>

void square(int n);
void _square(int* n);


void swap(int a, int b);
void _swap(int* a, int *b);

int main(){
    int age = 22;
    int *ptr = &age;
    int _age = *ptr;
    printf("%d\n", _age);


    printf("%p\n", &age);
    printf("%p\n", ptr);
    printf("%p\n", &ptr);


    printf("%d\n", age);
    printf("%d\n", *ptr);
    printf("%d\n", *(&age));


    int number = 4;
    // call by value
    square(number);
    printf("n is : %d\n", number);

    // call by reference
    _square(&number);
    printf("n is : %d\n", number);

    int x = 3, y = 5;
    swap(x, y);
    printf("x = %d & y %d\n", x , y);

    // call by reference
    swap(&x, &y);
    printf("x = %d & y %d\n", x , y);
    return 0;
}

void square(int n){
    n = n * n;
    printf("n is : %d\n", n);
}


void _square(int* n){
    *n = *n * *n;
    printf("n is : %d\n", *n);
}

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

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