1#include <stdlib.h> 2#include <ctype.h> 3 4long long atoll(const char *s) 5{ 6 long long n=0; 7 int neg=0; 8 while (isspace(*s)) s++; 9 switch (*s) { 10 case '-': neg=1; 11 case '+': s++; 12 } 13 /* Compute n as a negative number to avoid overflow on LLONG_MIN */ 14 while (isdigit(*s)) 15 n = 10*n - (*s++ - '0'); 16 return neg ? n : -n; 17} 18