Python 检查整数输入 [英] Python check for integer input

问题描述

我试图允许用户输入我的程序，但是当他们输入一个字符串时，我的程序失败了.这是一个更大的程序，但我试图纠正这个问题，到目前为止:

I am trying to allow a user to input into my program, however when they enter a string my program fails. It is for a bigger program but was trying to correct the problem, I have so far:

data = raw_input('Enter a number: ')
number = eval(data)
if type(number) != int:
     print"I am afraid",number,"is not a number"
elif type(number) == int:
    if data > 0:
        print "The",number,"is a good number"
    else:
        print "Please enter a positive integer"

当用户输入一个字符串时，它返回:

when the user enters a string, it returns:

number = eval(data)
  File "<string>", line 1, in <module>
NameError: name 'hel' is not defined

任何帮助将不胜感激.

推荐答案

您正在使用 eval，它计算在当前上下文中作为 Python 表达式传递的字符串.你想做的只是

You're using eval, which evaluate the string passed as a Python expression in the current context. What you want to do is just

data = raw_input('Enter a number: ')
try:
    number = int(data)
except ValueError:
    print "I am afraid %s is not a number" % data
else:
    if number > 0:
        print "%s is a good number" % number
    else:
        print "Please enter a positive integer"

这将尝试将输入解析为整数，如果失败，则显示错误消息.

This will try to parse the input as an integer, and if it fails, displays the error message.

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