标签：style blog color ar os 使用 sp for div
Implement atoi to convert a string to an integer.
Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.
Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.
注意点：
1)前缀空格
2)正负号
3)溢出 (可以使用long long int防止溢出)
1 int atoi(const char *str) 2 { 3 int flag = 1; 4 int i = 0; 5 long long int ret = 0; 6 7 if (NULL == str) 8 return 0; 9 while ((str[i] != ‘\0‘) && (str[i] == ‘ ‘)) 10 i++; 11 12 if (str[i] == ‘+‘) 13 { 14 flag = 1; 15 i++; 16 } 17 else if (str[i] == ‘-‘) 18 { 19 flag = -1; 20 i++; 21 } 22 23 while ((str[i] != ‘\0‘) && (str[i] >= ‘0‘ && str[i] <= ‘9‘)) 24 { 25 ret = ret * 10 + (str[i] - ‘0‘); 26 if ((flag == 1) && (ret * flag > INT_MAX)) 27 return INT_MAX; 28 if ((flag == -1) && (ret * flag < INT_MIN)) 29 return INT_MIN; 30 i++; 31 } 32 return (int)ret * flag; 33 }
leetcode 8.String to Integer (atoi)
标签：style blog color ar os 使用 sp for div
原文地址：http://www.cnblogs.com/ym65536/p/4082974.html
