Why Xcode C compiler does not display properly some of the ASCII table characters?

I'm developing a program in C using Xcode.To be practical let's take the following code

#include <stdio.h>int main () {    printf("%c",3);}

It's supposed to display the hearts character but it doesn't,instead just a interrogation icon show's up!And,at least for me,this is happening for many other 'special' characters.Anyone knows the reason of this?