100% Trying to swap no.s with & without using pointers

// Online C compiler to run C program online
#include <stdio.h>
int swapptr(int p, int q)
{
    int tatkal;
    printf("\n numbers before swapping in the called function: p=%d,q=%d",p,q);
    tatkal=p;
    p=q;
    q=tatkal;
    printf("\n numbers after swapping as printed in the function: p=%d,q=%d",p,q);
   
}
void main()
{
    int a=4,b=5;
    printf("\n numbers before swapping: a=%d,b=%d",a,b);
    swapptr(a,b);
    printf("\n values of a=%d,b=%d after returning back from called function",a,b);
}
   తెరమీద 

numbers before swapping: a=4,b=5
 numbers before swapping in the called function: p=4,q=5
 numbers after swapping as printed in the function: p=5,q=4

 values of a=4,b=5 after returning back from called function 

గమనిక a  మరియు b  విలువలు ఎందుకు  మారలేదో  ఆలోచించగలరు. ఇంతవరకు చేసినది కాల్ బై వాల్యూ పధ్ధతి   

 క్రింద ఉన్నది  కాల్ బై రెఫరెన్స్ పధ్ధతి 
#include <stdio.h>
int swapptr(int *p, int *q)
{
    int tatkal;
    tatkal=*p;
    *p=*q;
    *q=tatkal;
}
void main()
{
    int a=4,b=5;
    printf("\n numbers before swapping: a=%d,b=%d",a,b);
    swapptr(&a,&b);
    printf("\n numbers after swapping: a=%d,b=%d",a,b);
}

తెరమీద 

numbers before swapping: a=4,b=5
 numbers after swapping: a=5,b=4