CODEWITHSUNDEEP
c#regex
Raheel Khan
Raheel Khan

Reputation: 14787

Regular expression C#

Having trouble determining if a file name conforms to a specific convention as follows. Using regular expression in C# .Net 4.0.

Valid Format: xxxxT_SSS_sss[i]_t#y.png
where
// x = Any single character.
// T = Digit: 1 to 7 inclusive.
// _SSS = Positive Integer: 000 to 999 inclusive. Always padded with leading zeros.
// _sss = Positive Integer: 000 to 999 inclusive. Always padded with leading zeros.
// i = Random text of any length including any characters. Will always be enclosed in square [] brackets. Optional.
// _t = Positive Integer: 0 to 999 inclusive. Not padded. Optional.
// #y = Positive Integer: 0 to 999 inclusive. Not padded. Optional.

UPDATE

Valid file names:
File1_000_000.png
File1_000_000_1.png
File1_000_000#2.png
File1_000_000_1#2.png
File1_000_000[text].png
File1_000_000[text]_1.png
File1_000_000[text]#2.png
File1_000_000[text]_1#2.png

The regex I've been trying is: ^(.{4}\\d_\\d{3}_\\d{3}(\\[\\w\\s]+\\])?(_\\d{1,3})?(\\#\\d{1,3})?)

This returns true for all the sample file names BUT, if I change File1_000_000[text]_1#2.png to File1_000_000[text]_#2.png by deleting the digit 1, it still returns true. The underscore is a part of the _t.

Upvotes: 3

Views: 364

Answers (6)

José Mira
José Mira

Reputation: 751

@"^.{4}[2-7](_\d{3}){2}(\[.+\])?(_\d{1,3})?(\#\d{1,3})?\.png$"

Upvotes: 0

Sufian Latif
Sufian Latif

Reputation: 13356

This one should work:

^.{4}[2-7]{3}(_[0-9]{3}){2}(\[.+?\])?(_[1-9][0-9]{0,2})?(#[1-9][0-9]{0,2})?\.png$

Upvotes: 0

Sam Greenhalgh
Sam Greenhalgh

Reputation: 6136

This unit test will fail because you have specified the pattern must have an integer 2-7 at the 4th character positionm, where as File1 has 1.

[Test]
public void StackOverflow()
{
    Regex pattern = new Regex(@"^.{4}[2-7](_\d{3}){2}(\[[^\]]+\])?(_\d{1,3})?(#\d{1,3})?\.png$");

    Assert.IsTrue(pattern.IsMatch("File1_000_000.png"));
    Assert.IsTrue(pattern.IsMatch("File1_000_000_1.png"));
    Assert.IsTrue(pattern.IsMatch("File1_000_000#2.png"));
    Assert.IsTrue(pattern.IsMatch("File1_000_000_1#2.png"));
    Assert.IsTrue(pattern.IsMatch("File1_000_000[text].png"));
    Assert.IsTrue(pattern.IsMatch("File1_000_000[text]_1.png"));
    Assert.IsTrue(pattern.IsMatch("File1_000_000[text]#2.png"));
    Assert.IsTrue(pattern.IsMatch("File1_000_000[text]_1#2.png"));

    Assert.IsFalse(pattern.IsMatch("File1_000_000[text]_#2.png"));
}

Upvotes: 0

Jason
Jason

Reputation: 3960

Based on you "valid format", this will do the trick

^(?i)([a-z]{4}[2-7](_\d{3}){2}(\[.*?[^0-9]\])?(_\d{1,3}?)?(#\d{1,3}?)?\.png)$

remove (?i) to make the match case sensitive, and change [2-7] to [1-7] to make it match the files you gave (you said valid were 2-7, but your sample files are File1...)

Upvotes: 1

Rich O'Kelly
Rich O'Kelly

Reputation: 41757

A question on regex that doesn't involve HTML parsing, is a rarity!

Try the following:

@"^.{4}[2-7](_\d{3}){2}(\[.*?\])?(_\d{1,3})?(#\d{1,3})?\.png$"

This breaks down into:

^             Start of string
.{4}          Any character, exactly 4 times
[2-7]         A number in the range 2 - 7 once
(_\d{3}){2}   An underscore followed by 3 numbers, twice
(\[.*?\])?    An opening square bracket followed by any number of characters and closed by a square bracket 0 or 1 times
(_\d{1,3})?   An underscore followed by at least 1 and up to 3 numbers 0 or 1 times
(#\d{1,3})?   A pound (#) followed by at least 1 and up to 3 numbers 0 or 1 times
\.png$        Ending in .png

Upvotes: 2

Ry-
Ry-

Reputation: 224913

I'll just rewrite one, here:

^.{4}[2-7](_\d{3}){2}(\[[^\]]*\])?(_\d{1,3})?(\#\d{1,3})?\.png$

The problem right now is that you're not matching .png and you're not anchoring the end - the match ends prematurely. Also, you can avoid the double-escaping by prefixing your string with @:

@"^.{4}[2-7](_\d{3}){2}(\[[^\]]*\])?(_\d{1,3})?(\#\d{1,3})?\.png$"

Upvotes: 2

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