Question

What is the regular expression for a decimal with a precision of 2?

Valid examples:

123.12 2 56754 92929292929292.12 0.21 3.1 

Invalid examples:

12.1232 2.23332 e666.76 

The decimal point may be optional, and integers may also be included.

Answer 1

Valid regex tokens vary by implementation. A generic form is:

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

More compact:

\d+(\.\d{1,2})? 

Both assume that both have at least one digit before and one after the decimal place.

To require that the whole string is a number of this form, wrap the expression in start and end tags such as (in Perl’s form):

^\d+(\.\d{1,2})?$ 

To match numbers without a leading digit before the decimal (.12) and whole numbers having a trailing period (12.) while excluding input of a single period (.), try the following:

^(\d+(\.\d{0,2})?|\.?\d{1,2})$ 

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Added

Wrapped the fractional portion in ()? to make it optional. Be aware that this excludes forms such as 12. Including that would be more like ^\d+\\.?\d{0,2}$.

Added

Use ^\d{1,6}(\.\d{1,2})?$ to stop repetition and give a restriction to whole part of the decimal value.