Python创建计算器

这是使用正则表达式的可能解决方案概述。错误检查留作练习。如果这不是家庭作业，并且您想查看充实的解决方案，请在此处查看

import re# input is a list of tokens (token is a number or operator)tokens = raw_input()# remove whitespacetokens = re.sub('s+', '', tokens)# split by addition/subtraction operatorstokens = re.split('(-|+)', tokens)# takes in a string of numbers, *s, and /s. returns the resultdef solve_term(tokens):    tokens = re.split('(/|*)', tokens)    ret = float(tokens[0])    for op, num in <FILL THIS IN>:        # <apply the operation 'op' to the number 'num'>    return ret# initialize final result to the first term's valueresult = solve_term(tokens[0])# calculate the final result by adding/subtracting termsfor op, num in <FILL THIS IN>:    result +=  solve_term(num) * (1 if op == '+' else -1)print result