Noob Q: I have char temp = 128. How do I convert "temp" into string 128\0 ?

As title goes,
I have

char temp = 128// this is the result of a A/D conversion from microcontroller and it could be a number between 0 and 1023.

I'm trying to send this value in temp through USART, which I have both functions

void usart_pstr(char *s) {
    // loop through entire string
    while (*s) {
        usart_putchar(*s);
        s++;
    }
}
void usart_putchar(char data) {
	// Wait for empty transmit buffer
	while ( !(UCSR0A & (1<<UDRE0)) );
	// Start transmission
	UDR0 = data;
}

But on the receiving end , the serial port program only takes strings. So I'm wondering how do I convert "temp" into string "128\0" (instead of whatever 128 corresponds to in ASCII table) ?

Tags: C