章节 4-8 操作符判断怎么写，课程别讲一半不说了呀

源代码如下

"""
1、输入了一个数字，然后输入操作符号，然后输入一个数字，然后就算出结果
2、输入了一个数字，然后输入操作符号，然后输入一个数字，然后输入操作符号，然后输入一个数字..
然后就算出结果
 
"""
# 声明一个变量，来记录到底是第几次运算
number_of_times = 1
while True:
    # 判断到底是不是第一次计算
    if number_of_times == 1:
        result = input("请输入第一个数字:")
        operator = input("请输入操作符号:")
        if operator == "q":
            print("计算程序退出")
            break
        elif operator == "c":
            print("计算器清零，重新开始计算")
            result = 0
            number_of_times = 1
            continue
        second_number = input("请输入第二个数字:")
        result = float(result)
        second_number = float(second_number)
        if operator == "+":
            result += second_number
        elif operator == "-":
            result -= second_number
        elif operator == "*":
            result *= second_number
        elif operator == "/":
            result /= second_number
        else:
            print("没有匹配到正确的操作符，操作符号有错误")
 
        print("计算的结果是:"+ str(result))
        number_of_times += 1
    else:
        operator = input("请输入操作符号:")
        if operator == "q":
            print("计算程序退出")
            break
        elif operator == "c":
            print("计算器清零，重新开始计算")
            result = 0
            number_of_times = 1
            continue
        second_number = input("请输入第二个数字:")
        result = float(result)
        second_number = float(second_number)
        if operator == "+":
            result += second_number
        elif operator == "-":
            result -= second_number
        elif operator == "*":
            result *= second_number
        elif operator == "/":
            result /= second_number
        else:
            print("没有匹配到正确的操作符，操作符号有错误")
 
        print("计算的结果是:"+ str(result))
        number_of_times += 1

怒焰狂暴 2023-07-04

源自：打好 Python 开发基石 4-8 【案例】基于重复计算实现基础计算器

收起

1回答

好帮手慕小猿 2023-07-04 10:26:49

同学，你好！可以对输入的操作符进行判断，看操作符是否在特定的运算符内。若是在运算符内，对操作符进行最终赋值，不在操作符内则进行下一次循环

完整参考代码如下：

number_of_times = 1
while True:
    # 判断到底是不是第一次计算
    if number_of_times == 1:
        result = input("请输入第一个数字:")
        operator = input("请输入操作符号:")
        if operator  in ["+","-","*","/"]:
            final_operator=operator
        else:
            print("没有匹配到正确的操作符，操作符号有错误")
            continue
        if operator == "q":
            print("计算程序退出")
            break
        elif operator == "c":
            print("计算器清零，重新开始计算")
            result = 0
            number_of_times = 1
            continue
        second_number = input("请输入第二个数字:")
        result = float(result)
        second_number = float(second_number)
        if final_operator == "+":
            result += second_number
        elif final_operator == "-":
            result -= second_number
        elif final_operator == "*":
            result *= second_number
        elif final_operator == "/":
            result /= second_number
        else:
            print("没有匹配到正确的操作符，操作符号有错误")
            continue
        print("计算的结果是:" + str(result))
        number_of_times += 1
    else:
        operator = input("请输入操作符号:")
        if operator  in ["+","-","*","/"]:
            final_operator=operator
        else:
            print("没有匹配到正确的操作符，操作符号有错误")
            continue
        if operator == "q":
            print("计算程序退出")
            break
        elif operator == "c":
            print("计算器清零，重新开始计算")
            result = 0
            number_of_times = 1
            continue
        second_number = input("请输入第二个数字:")
        result = float(result)
        second_number = float(second_number)
        if final_operator=="+":
            result+=second_number
        elif final_operator == "-":
            result -= second_number
        elif final_operator == "*":
            result *= second_number
        elif final_operator == "/":
            result /= second_number
        print("计算的结果是:" + str(result))
        number_of_times += 1

祝学习愉快~

收起回答

提问者怒焰狂暴 #1

o ，if...in的语法还没江街道，难怪老师不说，好哒...知道了

2023-07-04 11:06:50
泰斯塔罗莎 #2

这个还是有明显的bug，输入q提示没有匹配到正确的操作符，操作符号有错误

2023-08-14 10:28:54

好帮手慕小猿回复泰斯塔罗莎 #3

同学，你好！同学可参考以下代码：

number_of_times = 1
while True:
    # 判断到底是不是第一次计算
    if number_of_times == 1:
        result = input("请输入第一个数字:")
        operator = input("请输入操作符号:")
        if operator == "q":
            print("计算程序退出")
            break
        if operator == "c":
            print("计算器清零，重新开始计算")
            result = 0
            number_of_times = 1
            continue
        if operator  in ["+","-","*","/"]:
            final_operator=operator
        else:
            print("没有匹配到正确的操作符，操作符号有错误,请重新输入数字及操作符")
            continue
 
        second_number = input("请输入第二个数字:")
        result = float(result)
        second_number = float(second_number)
        if final_operator == "+":
            result += second_number
        elif final_operator == "-":
            result -= second_number
        elif final_operator == "*":
            result *= second_number
        elif final_operator == "/":
            result /= second_number
        else:
            print("没有匹配到正确的操作符，操作符号有错误")
            continue
        print("计算的结果是:" + str(result))
        number_of_times += 1
    else:
        operator = input("请输入操作符号:")
 
        if operator == "q":
            print("计算程序退出")
            break
        if operator == "c":
            print("计算器清零，重新开始计算")
            result = 0
            number_of_times = 1
            continue
        if operator  in ["+","-","*","/"]:
            final_operator=operator
        else:
            print("没有匹配到正确的操作符，操作符号有错误")
            continue
        second_number = input("请输入第二个数字:")
        result = float(result)
        second_number = float(second_number)
        if final_operator=="+":
            result+=second_number
        elif final_operator == "-":
            result -= second_number
        elif final_operator == "*":
            result *= second_number
        elif final_operator == "/":
            result /= second_number
        print("计算的结果是:" + str(result))
        number_of_times += 1