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题目：
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.
虽然是个简单题，但是要考虑的细节挺多的，比如输入空串的话如何输出，输入有+，-号的话怎么办，如果遇到无效输入怎么办？数字溢出了该如何输出？如果遇到的是面试，最好都要弄清楚。
class Solution { public: int myAtoi(string str) { if (str == "") return 0; int flag = 1; int res = 0; string::const_iterator iter = str.begin(); while (*iter == ‘ ‘ && iter != str.end()) iter++; if (*iter == ‘+‘ || *iter == ‘-‘){ if (*iter == ‘-‘) flag = -1; *iter++; } while (iter!=str.end() && isValidNum(*iter)) { int tmp = *iter - ‘0‘; if (res > (INT_MAX - tmp) / 10 && flag == 1) return INT_MAX; if (res > (INT_MAX - tmp) / 10 && flag == -1) return INT_MIN; res = res * 10 + tmp; iter++; } return flag*res; } bool isValidNum(char c) { return c >= ‘0‘ && c <=‘9‘; } };
【LeetCode】8. String to Integer (atoi)
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原文地址：http://www.cnblogs.com/Doctengineer/p/5858896.html
