将字符串转换成整数

输入描述:

输入一个字符串,包括数字字母符号,可以为空

输出描述:

如果是合法的数值表达则返回该数字，否则返回0

Python代码1:

# -*- coding:utf-8 -*-
class Solution:
    def StrToInt(self, s):
        # write code here
        if len(s)==0:
            return 0
        end = len(s)-1
        begin = -1
        temp = 1
        int_s = 0
        if s[0]==‘-‘ or s[0]==‘+‘:
            begin = 0
        for i in range(end,begin,-1):
            if s[i]<‘0‘ or s[i]>‘9‘:
                return 0
            int_s += temp*int(s[i])
            temp = temp *10
        if s[0]==‘-‘:
            int_s = -int_s
        return int_s

Python代码2

使用列表，当成大数处理，牛客一直通不过，最终还是得将字符串改为整数，很纳闷

# -*- coding:utf-8 -*-
class Solution:
    # 大数问题
    def StrToInt(self, s):
        # write code here
        if len(s) == 0:
            return 0
        if len(s)==1 and (s[0]<‘0‘ or s[0]>‘9‘):
            return 0
        end = len(s) - 1
        begin = -1
        int_s = [0]*len(s)
        if s[0] == ‘-‘ or s[0] == ‘+‘:
            begin = 0
        for i in range(end, begin, -1): #range()函数，左闭右开 
            if s[i]>=‘0‘ and s[i]<=‘9‘:
                int_s[i] = s[i]
            else:
                return 0
        if s[0] == ‘-‘:
            int_s[0] = ‘-‘
        if s[0]==‘+‘:
            int_s = int_s[1:]
        return int(‘‘.join(int_s))