[LeetCode] String to Integer(atoi)

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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.

LeetCode: https://oj.leetcode.com/problems/string-to-integer-atoi/

题解：这道题总体来说还比较简单，不涉及算法；但需要考虑全面：字符串两边的空格，正负号，字符串的数值大小，是否超出整形所能表达的范围

public class Solution {    public int atoi(String str) {        if(str == null || str.length() == 0)            return 0;        double number = 0;        int flag = 1;        int i;        str = str.trim();        if(str.charAt(0) == '-'){            flag = -1;            str = str.substring(1);        }        else if(str.charAt(0) == '+'){            flag = 1;            str = str.substring(1);        }                for(i = 0;i < str.length(); i++){            if(str.charAt(i) >= '0' && str.charAt(i) <= '9'){                number = number*10 + (str.charAt(i) - '0');            }            else                break;        }        number = number * flag;        if(number > Integer.MAX_VALUE)            return Integer.MAX_VALUE;        if(number < Integer.MIN_VALUE)            return Integer.MIN_VALUE;                    return (int) number;    }}

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