#include <stdlib.h>#include <ctype.h>intatoi(const char*s){int n=0, neg=0;while(isspace(*s)) s++;switch(*s) {case'-': neg=1;case'+': s++;}/* Compute n as a negative number to avoid overflow on INT_MIN */while(isdigit(*s))
n =10*n - (*s++ -'0');return neg ? n : -n;}