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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.
Update (2015-02-10):
The signature of the C++ function had been updated. If you still see your function signature accepts a const char * argument, please click the reload button to reset your code definition.
spoilers alert... click to show requirements for atoi.
1 class Solution { 2 public: 3 int myAtoi(string str) { 4 long long result = 0; 5 int sign = 1; 6 int size = str.length(); 7 int index = 0; 8 9 while(str[index] == ‘ ‘ && index < size) index++; 10 11 if(str[index] == ‘+‘) index++; 12 else if(str[index] == ‘-‘){ 13 index++; 14 sign = -1; 15 } 16 17 for(; index < size; index++){ 18 if(str[index] < ‘0‘ || str[index] > ‘9‘) break; 19 20 result = result * 10 + str[index] - ‘0‘; 21 if(result > INT_MAX) return sign == 1 ? INT_MAX : INT_MIN; 22 } 23 return (int) sign * result; 24 } 25 };
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原文地址：http://www.cnblogs.com/amazingzoe/p/4595470.html
