如何验证字符串是否为有效浮点数? [英] How can I verify if a string is a valid float?

问题描述

我想要做的是验证一个字符串是否是数字——一个浮点数——但我还没有找到一个字符串属性来做到这一点.可能一个都没有.这段代码有问题:

What I want to do is to verify if a string is numeric -- a float -- but I haven't found a string property to do this. Maybe there isn't one. I have a problem with this code:

N = raw_input("Ingresa Nanometros:");
if ((N != "") and (N.isdigit() or N.isdecimal())):
    N = float(N);
    print "%f" % N;

如您所见，我只需要取数字，无论是十进制数还是浮点数.N.isdecimal() 没有解决我想到的问题.

As you can see, what I need is to take only the numbers, either decimal or float. N.isdecimal() does not resolve the problem that I have in mind.

推荐答案

try:
    N = float(N)
except ValueError:
    pass
except TypeError:
    pass

这会尝试将 N 转换为 float.但是，如果不可能(因为它不是数字)，它将pass(什么都不做).

This tries to convert N to a float. However, if it isn't possible (because it isn't a number), it will pass (do nothing).

我建议你阅读 try 和except 块.

I suggest you read about try and except blocks.

你也可以这样做:

try:
    N = float(N)
except (ValueError, TypeError):
    pass

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