I am trying to create a regular expression that validates an red/green/blue value expression. The expressions that I need my regular expression to match include:
Currently, I have the following regular expression:
^rgba?\((([+-]?\d+(\.\d+)?),\s*){2}[+-]?\d+(\.\d+)?(,\s*(0?\.\d|[01]))?\)$
This expression works for #1, #2, #3, #6, and #7. However, it fails for #4 and #5. I keep staring at the last group. To me, it looks like it should accept a decimal. Clearly, it's not though. What am I doing wrong?
The problem in your regular expression, is that your expression doesn't allow for values greater than length 1 behind the last decimal point. Considering the original regular expession:
^rgba?\((([+-]?\d+(\.\d+)?),\s*){2}[+-]?\d+(\.\d+)?(,\s*(0?\.\d|[01]))?\)$
You will get a positive value for rgba(1, 2, 35.132, 0.7), but negative for rgba(1, 2, 35.132, 0.75).
The solution is adding a star to the last \d digit denotator, indicating that there can be any amount of digits. A plus would be even better, as it would detect faulty values that have 0 digits behind a decimal point, by requiring at least 1 of the \d instance.
^rgba?\((([+-]?\d+(\.\d+)?),\s*){2}[+-]?\d+(\.\d+)?(,\s*(0?\.\d*|[01]))?\)$