String to Interger (atoi)

最新推荐文章于 2022-07-27 16:48:14 发布

原创最新推荐文章于 2022-07-27 16:48:14 发布 · 445 阅读

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本文详细解析了atoi函数的实现原理，包括符号处理、数字读取、溢出检查及最终转换过程，旨在帮助开发者理解底层逻辑并正确使用。

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.

class Solution:
    # @return an integer
    def atoi(self, str):
        INT_MAX = 2147483647; INT_MIN = -2147483648
        sum = 0 
        i = 0
        sign = 1
        if str == '': return 0 
        while i < len(str) and str[i].isspace():
            i += 1
        if i < len(str) and str[i] == '-' :
            sign = -1
        if i < len(str) and (str[i] == '-' or str[i] == '+') :
            i += 1
        while i < len(str) and str[i].isdigit():
            digit = int(str[i])
            if INT_MAX / 10 >= sum :
                sum = sum * 10
            else :
                return INT_MAX if sign == 1 else INT_MIN
            if INT_MAX - digit >= sum :
                sum = sum + digit
            else :
                return INT_MAX if sign == 1 else INT_MIN
            i += 1
        return sign * sum