Regular expression does not match a number with e+ or e-

I want to match any number w开发者_开发百科ith a regular expression. I have written this expression (added whitespace for readability):

( ([0-9]+(\.[0-9]*)?) | (\.[0-9]+) )( (e|E)(\+|\-)[0-9](\.[0-9])? )?

This would need to match any number in one of the following forms:

• 12345
• 12.345
• .12345
• 12345.
• 12e-345 or 12E-345
• 12e+345 or 12E+345

It matches the first four notations, but the last four (those with e- and e+) don't. What have I done wrong? Thanks in advance.

Focus on that part of the expression:

(e|E)(\+|\-)[0-9](\.[0-9])?

You're only allowing one digit after e|E, optionally followed by a . and one other digit.

Maybe it is the final slashdot '\.'.

Also, there is no * so it will only allow one or two digits in the exponent.

(\.[0-9])? )?

You're looking for 1 digit after the [eE]. Change the ? to a +

( ([0-9]+(\.[0-9]*)?) | (\.[0-9]+) )( (e|E)(\+|\-)[0-9]+(\.[0-9])+ )?

Because the regex matches numbers of the form 12.34e+4.5. The [0-9](\.[0-9])? part should be changed to [0-9]+.

( ([0-9]+(\.[0-9]*)?) | (\.[0-9]+) )( (e|E)(\+|\-)[0-9]+ )?

See also How to detect a floating point number using a regular expression.

Use this: \d+[eE][+-]\d+|\d+\.?\d*|\.\d+