如何确保用户输入了数字？

Question

我已经编写了一个 BMI 计算器，但我希望有一种方法可以确保用户只输入数字，这样，如果输入了其他内容，就会再次提出问题。这是我的一些代码。

#Ask whether metric or imperial is to be used and ensures no typing errors
measure = input("Would you like to use Metric or imperial measurements? Please type i for imperial or m for metric  \n")

while(measure != "i") and (measure != "m"):
    measure =input("Please type a valid response. Would you like to use Metric or imperial measurements? Please type i for imperial or m for metric")

#Asks the users weight
if(measure == "i"):
    weights = input("Please type in your weight in stones and pounds- stones=")
    weightlb = input("- pounds=")
    weights = int(weights)
    weightlb = int(weightlb)
    weight = (weights*14)+weightlb

elif(measure == "m"):
    weight = input("Please type in your weight in kilograms=")

Answer 1

这就是 str.isdigit 的用途：

while( not measure.isdigit()) :
     measure =input("Please type numbers only ")

Answer 2

您可以简单地使用 try, except 循环和 while 循环。这就是我的意思：

intweight = 0
while True:
    try: 
        weight = float(input())
    except ValueError:
        print "Please enter a number"
    else:
        break
        intweight = weight

while 循环将强制用户输入一个字符串，直到它只包含数字。该程序将尝试将字符串转换为数字。如果有字母，except 部分将被激活。如果转换成功，else 部分将激活，从而打破循环。希望对您有所帮助！

如何确保用户输入了数字？

How to make sure that a user inputs a number?

python

validation

user-input

python-3.x