一个itoa的实现

//自己找到了一个itoa的实现 

void itoa(unsigned long val,char *buf,unsigned radix)
{
	char *p;/*pointer to traverse string*/
	char *firstdig;/*pointer to first digit*/
	char temp;/*temp char*/
	unsigned digval;/*value of digit*/

	p = buf;
	firstdig = p;/*save pointer to first digit*/

	do{
		digval =(unsigned)(val % radix);
		val /= radix;/*get next digit*/

		/*convert to ascii and store */
		if(digval > 9)
			*p++ = (char)(digval - 10 + 'a ');/*a letter*/
		else 
			*p++ = (char)(digval + '0 ');/*a digit*/
	}while(val > 0);

		/*We now have the digit of the number in the buffer,but in reverse
		order.Thus we reverse them now.*/

	*p-- = '\0 ';/*terminate string;p points to last digit*/

	do{
		temp = *p;
		*p = *firstdig;
		*firstdig = temp;/*swap *p and *firstdig*/
		--p;
		++firstdig;/*advance to next two digits*/
	}while(firstdig < p);/*repeat until halfway*/
}