Question

Why the below program gives the output :A.

what is use of \n after the format specifier %d?
I have tried it on Linux, Windows and ideone.

#include <stdio.h>
int main(void)
{
    char p[]="%d\n";
    p[1]='c';
    printf(p,65);
    return 0;
}

Answer 1

First, your program modifies the format string: it becomes “%c\n”. Then it prints 65, which is re-interpreted as an ASCII code, which is an upper-case A.

This is identical to

printf("%c\n", 65);

or even

printf("%c\n", 'A');

because char values are converted to int when passed to variadic functions such as printf.