[LeetCode]String to Integer (atoi)-优快云博客

本文链接：https://blog.youkuaiyun.com/zxdfc/article/details/48709819

本文介绍了一个将字符串转换为整数（atoi）的Java实现方法。通过详细解析输入字符串，处理正负号及非数字字符，确保转换过程正确且符合整数范围限制。

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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.

注意：题目的数据真的可以，卡了好久

public class Solution {
    public int myAtoi(String str) {
      if(str.trim().equals(""))
			return 0;
		long res = 0;
		int sign = 1, i = 0;
		str = str.trim();
		if (str.charAt(i) == '-' || str.charAt(i) == '+') {
			sign = str.charAt(i) == '-'?-1:1;
			i++;
		}
		
		for(;i<str.length(); i++){
			
			if(str.charAt(i)>='0' && str.charAt(i)<='9'){
				
				if(res*sign>=Integer.MAX_VALUE)
					return Integer.MAX_VALUE;
				if(res*sign<=Integer.MIN_VALUE)
					return Integer.MIN_VALUE;
				res = res*10+(str.charAt(i)-'0');
				
			}else{
				if(res*sign>=Integer.MAX_VALUE)
					return Integer.MAX_VALUE;
				if(res*sign<=Integer.MIN_VALUE)
					return Integer.MIN_VALUE;
				return (int)res*sign;
			}
				
		}
		if(res*sign>=Integer.MAX_VALUE)
			return Integer.MAX_VALUE;
		if(res*sign<=Integer.MIN_VALUE)
			return Integer.MIN_VALUE;
		return (int)(res*sign);
    }
}