What is the use of %p in C

// %p prints the address in hexadecimal format 
#include <stdio.h>

int main() 
{
    int var = 10;
    
    // declaring pointer variable to store address of var
    int *ptr = &var; 

    printf("The address in decimal : %d \n", ptr); 
    printf("The address in hexadecimal : %p \n", ptr); 

    return 0; 
}