Regular expression for matching start of string with

Question

I need help to built regular expression for

string which does not start with pcm_ or PCM_

any guess!!!

does it allow pCM or PCm or PcM etc. ? – Imran Rizvi Jan 19 '12 at 12:34 — Imran Rizvi, Jan 19 '12 at 12:34

score 5 · Answer 1 · answered Jan 19 '12 at 12:18

5

No need to use regular expression. Use String.startsWith() method.

if (!str.StartsWith("pcm_",StringComparison.InvariantCultureIgnoreCase)) {}

answered Jan 19 '12 at 12:18

KV Prajapati

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score 2 · Answer 2 · answered Jan 19 '12 at 12:23

2

if (String.startsWith("pcm_") || String.startsWith("PCM_"))
{
    //...
}

answered Jan 19 '12 at 12:23

gabsferreira

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score 1 · Answer 3 · edited May 23 '17 at 11:48

1

see similar link

Regex pattern for checking if a string starts with a certain substring?

edited May 23 '17 at 11:48

Community

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answered Jan 19 '12 at 12:29

Imran Rizvi

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This would allow "!pcm_" and "!PCM_" at the start of the string. – stema Jan 19 '12 at 12:38
Your modification hasn't improved the expression. "!" is in a regex just the character "!" and not a NOT operater, there is also no AND operator in regex. – stema Jan 19 '12 at 12:45

score 1 · Accepted Answer · answered Jan 19 '12 at 12:30

1

The regex solution would be

^(?i)(?!pcm_)

(?i) is the inline version of RegexOptions.IgnoreCase

^ matches the start of the string

(?!pcm_) is a negative lookahead assertion, that is true if the string does not start with "pcm_" or "PCM_" (but also "PcM_, ...)

answered Jan 19 '12 at 12:30

stema

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that great hint thanks. i have used this as it is for vbscript ^(?![pP][cC][mM]_) – 0cool Jan 24 '12 at 14:32

score 1 · Answer 5 · answered Jan 19 '12 at 12:33

1

As already pointed out, you don't need to use regular expressions for this, but if you wanted to you could use one with negative lookahead like so: ^(?!pcm_|PCM_).*$

answered Jan 19 '12 at 12:33

jfiskvik

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score 0 · Answer 6 · answered Jan 19 '12 at 12:36

0

No need for a Regex here, simply use String.StartsWith http://msdn.microsoft.com/en-us/library/system.string.startswith.aspx

answered Jan 19 '12 at 12:36

Guillaume Slashy

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Regular expression for matching start of string with

6 Answers6