[c++期末100题]将字符串 s 转化为整型数返回。注意负数处理方法。

#include
#include  
using namespace std; 
void grading(); 
 
 
int atoi(char s[]) 
{ 
 int num = 0; 
 int i = (s[0] == '-' ? 1 : 0); 
 for (; s[i] != ''; i++) 
 { 
 	num = num * 10 + (s[i] - '0'); 
 } 
 if (s[0] == '-') 
 	num = -num; 
 return num; 
}


int main() 
{ 
 char num1[20] = "-123"; 
 char num2[20] = "456"; 
 cout<