Thread: pass pointer into function and return pointer from function

I am trying to write code in which i want to pass pointer into function and return pointer from function

This is my test code

Code:

 #include<stdio.h>
#include<stdlib.h> 


int *foo( int *ptr )
{
   int *qtr = malloc (sizeof(*qtr));
   
    if (qtr == NULL) 
    { 
        printf("Memory not allocated.\n"); 
        return 0; 
    } 
   
   qtr = ptr;
   
   return qtr;
}
    
int main()
{
    
    int *ptr = malloc (sizeof(*ptr));


    if ( ptr == NULL ) 
    { 
        printf("Memory not allocated.\n"); 
        return 1; 
    }     
    
    ptr = foo ( ptr );    
    
    return 0;    
}

I am trying figure out what happen when we pass pointer into function and return pointer from function by printing memory location value. I don't have any idea how to make furthrt progress