如何检查用户输入是否为数字

Question

我正在制作一个教育数学游戏，并希望确保所有的用户输入都是有效的，即一个数字。当他们输入一个字母或符号时，需要显示一条消息，上面写着“无效，请再试一次”。有人能帮我吗？这是我的密码：

import random

counter=0
score = 0
incorrect = 0

name=input("What is your name?")
print("Hi",name,",welcome to your math quiz!")

questions = ["10*2","4-2","6+12","6*4","12-5","6+54","1*0","3-6","4+0","65-9"]
answers=["20","2","18","24",'7','60','0','-3','4','56']

idx_questions = list(enumerate(questions))
idx_answers = list(enumerate(answers))

random.shuffle(idx_questions)

counter=0
inputs = []
for idxq, question in idx_questions:
    print("Question",counter+1,":",question)
    ans = input("What is the answer? ")
    counter=counter+1

    inputs.append(ans)
    for idxa, answer in idx_answers:
        if idxq == idxa and ans == answer:
            print("Correct")
            score=score+1
            print("Correct Answers=",score)
            print("Incorrect Answers=",incorrect)

        elif idxq == idxa and ans != answer:
            print("Incorrect. The answer is", answer)
            incorrect=incorrect+1
            print("Correct Answers=",score)
            print("Incorrect Answers=",incorrect)

print("End of quiz")
print(name,"your score is",score,"out of 10")
print(score*10,"/100",score,",%")
counter=0
while counter<10:
    print("Question",counter+1,": Your answer =", inputs[counter])
    counter=counter+1

Answer 1

您要寻找的是string类上的isdigit方法。

即https://docs.python.org/3/library/stdtypes.html#str.isdigit

如果用户没有输入有效数字，您可以再次请求一个有效数字：

def get_answer():
    num_str = input("Please enter a number: ").lower()
    if (num_str.isdigit()):
        return num_str
    else:
        print("Invalid, please try again")
        return get_answer()

嗨，简，这个函数基本上会一直要求输入，直到用户输入一个数字为止。您所需要做的就是获得函数的ans变量，并且保证它将是一个数字。我在下面为你把所有的东西放在一起。实际上，我的代码中有一些错误(对不起！)我修好了。您的工作代码如下所示：

import random

counter=0
score = 0
incorrect = 0

name=input("What is your name?")
print("Hi",name,",welcome to your math quiz!")

questions = ["10*2","4-2","6+12","6*4","12-5","6+54","1*0","3-6","4+0","65-9"]
answers=["20","2","18","24",'7','60','0','-3','4','56']

idx_questions = list(enumerate(questions))
idx_answers = list(enumerate(answers))

random.shuffle(idx_questions)

def get_answer():
    num_str = input("Please enter a number: ").lower()
    if (num_str.isdigit()):
        return num_str
    else:
        print("Invalid, please try again")
        return get_answer()

counter=0
inputs = []
for idxq, question in idx_questions:
    print("Question",counter+1,":",question)
    ans = get_answer()
    counter=counter+1

    inputs.append(ans)
    for idxa, answer in idx_answers:
        if idxq == idxa and ans == answer:
            print("Correct")
            score=score+1
            print("Correct Answers=",score)
            print("Incorrect Answers=",incorrect)

        elif idxq == idxa and ans != answer:
            print("Incorrect. The answer is", answer)
            incorrect=incorrect+1
            print("Correct Answers=",score)
            print("Incorrect Answers=",incorrect)

print("End of quiz")
print(name,"your score is",score,"out of 10")
print(score*10,"/100",score,",%")
counter=0
while counter<10:
    print("Question",counter+1,": Your answer =", inputs[counter])
    counter=counter+1

如果你有任何问题，请回答！

Answer 2

isdigit()检查字符串是否由数字组成。你可以在Python文档里找到它。

示例：

string1 = '1234'
string.isdigit()

这将返回为True。

string2 = 'abcd'
string.isdigit()

这将返回为False。