pattern needed for validating string which can contain either no space or 2 spaces

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I need to generate a pattern which can validate a string

Either no space in a string, or if space exists there should be 3 parts separated by a space.

eg :

Valid vith space
7HKW8 01 MOD,PWA,SYSM,CPEN,CLV743,1110
(Part 1 : 7HKW8
Part 2 : 01
Part 3 : MOD,PWA,SYSM,CPEN,CLV743,1110)

Valid with no space
7HKW8
MOD,PWA,

Invalid
7HKW801 MOD,PWA,SYSM,CPEN,CLV743,1110
(It has only 2 parts seperated by space)
7HKW8 01MOD,PWA,SYSM,CPEN,CLV743,1110
(It has only 2 parts seperated by space)
7HKW8 01MOD PWA SYSM CPEN CLV743,1110
(It has more than 3 parts seperated by space)

Posted 19-Apr-11 2:09am

vinu_p

Updated 19-Apr-11 5:49am

Henry Minute

v2

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vinu_p 19-Apr-11 8:34am

I am validating contents in a xml , regex will be easy instead of extracting and doing some c# code

2 solutions

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#realJSOP · Answer 1 · 2011-04-19T02:14:00

Why use a regular expression? You didn't specify a language, so the following is in C#:

C#

var count = (from c in myString
             where c == ' '
             select c).Count();
valid = (count == 2 || count == 0);

Depending on the environment/context, I'd consider wait until it's time to parse the string, and validate it as part of the act of parsing:

C#

string[] parts = myString.Split(" ");
if (parts.Length != 1 || parts.Length != 3)
{
    return;
}

BillW33 · Answer 2 · 2011-04-19T04:30:00

Solution 2

There is a good regex tutorial here[^]
A good article on validating with regular expressions here[^]
There is also good regex info here[^]
Finally there is a regular expression tester here[^]

Posted 19-Apr-11 4:30am

BillW33