牛客网-python-表示数值的字符串

题目描述

请实现一个函数用来判断字符串是否表示数值（包括整数和小数）。例如，字符串"+100","5e2","-123","3.1416"和"-1E-16"都表示数值。 但是"12e","1a3.14","1.2.3","+-5"和"12e+4.3"都不是。

自己实现

class Solution:
    # s字符串
    def isNumeric(self, s):
        # write code here
        AllList = ['-','+','e','E','.','0','1','2','3','4','5','6','7','8','9']
        flag = 0
        for i in range(0,len(s)):
            if s[i] in AllList:
                if (s[i]=='+' or s[i]=='-') and (i==0 or s[i-1]=='E' or s[i-1]=='e'):
                    continue
                elif s[i]=='E' or s[i]=='e' and i!=0 and s[i-1] in AllList[6:] and i!=len(s)-1:
                    flag = 1
                    continue
                elif s[i]=='.' and flag == 0 and i!=len(s)-1 and s[i+1] in AllList[5:]:
                    flag = 1
                    continue
                elif s[i] in AllList[5:]:
                    continue
                else:
                    return False
            else:
                return False
        return True

讨论区代码：

#利用python中的正则模块进行匹配

# -*- coding:utf-8 -*-
class Solution:
    # s字符串
    def isNumeric(self, s):
        import re
        p=re.compile(r'^[\+\-]?\d*(\.\d+)?([eE][\+\-]?\d+)?$')
        return p.match(s)