help with a simple regular expression

[lockmac]

Hi guys. I am having trouble grasping regular expression (like many im guessing).

Anyways, I need a regular expression that will accept the following.

A number between 0 and 100 and .5 values are acceptable.

Eg. 40.5 is acceptable but 40.4 or 40.7 is not acceptable.

Thanks very much

 

[slugg]

let x = the number...

if(2 * x - (int)(2 * x) || x < 0 || x > 100)
{
number is bad
}
else
{
number is good
}

 

[lockmac]

thanks for that mate, but i cant use code for it, it has to be regular expression (this is to be used in an xml schema declaration

 

[Snapster]

Try

^\d{1,3}(\.[05])?$

matches 1 to 3 decimal numbers at the start and if any decimal point it expects it to be a 0 or a 1, hopefully!

 

[presidentender]

40.5 is okay. Is 40.0? What about 40?

Regular expressions work on Strings, so this is an important distinction. Assuming you want 40.0 and 0.0 and 100.0, not 40:

([1-9]?[0-9]([.0]|[.5]))|([100.0])|([0.0])

should work. I didn't test it. Check this out.

 

[lockmac]

Hey snapster- that worked a treat, except that it accepts values over 100, which is okay i guess, i can write some different logic to deal with that.

presidentender, 40 is okay, 40.0 is okay, but 40.4 isnt. Im basically wanting a full number (can have the decimal .0 put their if they want) but it can only increment in halves. Its for a student mark file and half marks are acceptable. and thanks for your string, but it didnt seem to work at all

 

[Snapster]

Ah yeh, forgot to test over 100

Try this:

^(([0-9]|[0-9][0-9])(\.[05])?|(100)(\.[0])?)$

It should allow 100 and 100.0 but not 100.5 too.