Simple regex. Get the number from [~21~]

I have a string that looks like this: [~21~]. How can I use regex to only return 21? The number can be any value (numbers), at any length. I am using Javascript with this regex, so if you coul开发者_StackOverflow社区d include that in your exsample, that would be great.

Thomas

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You can:

1. Remove any other characters than digits
2. Parse the resulting number to a real number instead of a string

Like:

var number = parseInt(str.replace(/[\D]/g, ""), 10);

Where:

• parseInt(..., 10) parses any string to a number in base 10
• str.replace(..., "") will remove characters (replace them with nothing)
• [\D] means: anything except digits

For example,

parseInt("[~21~]".replace(/[\D]/g, ""), 10) === 21;

Note that it will concatenate numbers in e.g. [~21~22~]; that will become 2122.

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A simple regex that will work in your case is:

[0-9]+

This will match a sequence of strings consisting of the characters: 0,1,2,3,4,5,6,7,8,9

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If you aren't worried about error-handling:

 var getTheNumber = function(a) { return a.substring(0, a.length-2).substring(2); }

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-*\d+(\.\d+)*

Contemplates negative and/or decimal numbers. This will extract any number of 1 or more digits no matter the string.