leetcode小白解题记录——第八题

8. String to Integer (atoi)

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.

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这一题好好看这些提示，细心处理，就不会有什么问题

public class Solution {    public int myAtoi(String str) {        //null or empty string        String s=str;if(s == null || s.length()==0) return 0;//去空格s=s.trim();//判断正负号boolean sign=true;int i=0;if(s.charAt(0)=='+'){i++;}else if(s.charAt(0)=='-'){sign=false;i++;}   //计算真实值double tmp=0;for(;i<s.length();i++){int digit=s.charAt(i)-'0';//将字符转换为数字if(digit<0 || digit>9) break;if(sign){tmp=tmp*10+digit;if(tmp > Integer.MAX_VALUE ) return Integer.MAX_VALUE;}else{tmp=tmp*10-digit;if(tmp<Integer.MIN_VALUE) return Integer.MIN_VALUE;}}return (int)tmp;}}