1 #include <stdlib.h>
2 #include <ctype.h>
3 
atoi(const char * s)4 int atoi(const char *s)
5 {
6 	int n=0, neg=0;
7 	while (isspace(*s)) s++;
8 	switch (*s) {
9 	case '-': neg=1;
10 	case '+': s++;
11 	}
12 	/* Compute n as a negative number to avoid overflow on INT_MIN */
13 	while (isdigit(*s))
14 		n = 10*n - (*s++ - '0');
15 	return neg ? n : -n;
16 }
17