call by value and call by reference demonstration

#include <stdio.h>  
    void swap_call_by_value(int , int );
    void swap_call_by_refrence(int *, int *); //prototype of the function   
    int main()  
    {  
        int a = 10;  
        int b = 20;   
        printf("Before swapping the values in main a = %d, b = %dn",a,b); // printing the value of a and b in main  
        swap_call_by_refrence(&a,&b);  
        printf("After using swapping function call by refrence values in main a = %d, b = %dn",a,b); // The values of actual parameters do change in call by reference, a = 10, b = 20  
        printf("nn");
        swap_call_by_value(a,b);
        printf("nn");
        printf("values in main after calling function call by valuen a = %d  b = %d ",a,b);
        
    }  
    void swap_call_by_refrence (int *a, int *b)  
    {  
        int temp;   
        temp = *a;  
        *a=*b;  
        *b=temp;  
    }  
    
    void swap_call_by_value (int a, int b)  
    {  
        int temp;   
        temp = a;  
        a=b;  
        b=temp;  
        printf("values in function of call by value a = %d  b = %d  n",a,b);
    }