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问题是这样子的：
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.
平时写程序过于急躁，思考不深入，写这个看似容易的程序真是死了一大批脑细胞啊！！！反思，对于数值处理的问题，以及字符串处理的问题。
最重要的是：会不会溢出，会不会越界！！！
以下是我的代码，感觉略臭略长。如有大神帮改，感激不尽啊！！！
class Solution { public: int atoi(const char *str) { int ret = 0; const char *fStr = str; int signflag = 1; int signCount = 0; int intCount = 0; if(fStr == NULL ) { return 0; } while(*fStr != ‘\0‘) { if(*fStr == 0x2D) { signflag = -1; ++signCount; fStr++; } if(*fStr == 0x2B) { signflag = 1; ++signCount; fStr++; } if(signCount > 1) { return 0; } if(isdigit(*fStr)) { if(ret == INT_MAX/10 && *fStr >= 0x38 && signflag == 1) { return INT_MAX; } else if(ret == INT_MAX/10 && *fStr > 0x38 && signflag == -1) { return INT_MIN; } ret = 10 *ret + (*fStr-0x30); ++fStr; ++intCount; if(intCount > 10) { return signflag >0 ? -INT_MIN-1 : INT_MIN; } } else if(*fStr ==‘ ‘) { if(intCount >= 1) { return ret * signflag; } else if(signCount >= 1 && intCount ==0 ) { return 0; } fStr++; } else return ret * signflag; } return ret * signflag; } };
任重道远，爱情不光是甜蜜，更是一份责任。。。加油！！！
LeetCode 8 :String to Integer (atoi)
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原文地址：http://www.cnblogs.com/bestwangjie/p/4261933.html
