itoa keil
/* reverse: reverse string s in place */
void reverse(char s[])
{
int c, i, j;
for (i = 0, j = strlen(s)-1; i<j; i++, j--) {
c = s;
s = s[j];
s[j] = c;
}
}
/* itoa: convert n to characters in s */
void itoa(int n, char s[])
{
int i, sign;
if ((sign = n) < 0) /* record sign */
n = -n; /* make n positive */
i = 0;
do { /* generate digits in reverse order */
s[i++] = n % 10 + '0'; /* get next digit */
} while ((n /= 10) > 0); /* delete it */
if (sign < 0)
s[i++] = '-';
s = '\0';
reverse(s);
}