Question about defining a Custom component in Sopc builder

ok...It's clear now on customIP side....but on nios side.....from the C code:

# include <stdio.h>

int main()

{

int *customAddress = 0x00000000;

customAddress[0] = x010;

printf(“my IP has value %d\m”,customAddress[0]);

}

if using prinf NiosII and CustomIP don't communicate, meaning that NiosII does not send data to CustomIP by printf.....in this context...what does printf() function serve to???

and for reading what command does it need???