Match hex 00 or NULL with Match pattern function

[concorpoly]

Hi, I am using Match pattern funciton to match NULL character and 0000 character in a string (hex display).

Someone told mu use the following regular expression:

^[\00]*, and [\00]*$ , and he said:

                \00 is Hex 00

                \0 un-defined

But I read some stuffs about regular  expression that \0x00 is Hex 00, \00 is Octal 000.I want to know what meaning the \00 is.

Please refer to the attached trim00.vi.

[mikeporter]

Match Pattern and Match Regular Expression are two different functions. With Match Pattern the string ^[\00]* matches any number of null characters starting at the beginning of the string, while the string [\00]*$ matches any number of null characters starting at the end of the string. Check the help for the Match Pattern function for more info.

Mike...

[concorpoly]

then [\00] maches NULL ? from ASCII, \x00 is NULL, but when I replaced \00 with \x00, the vi not worked well.

[RobCole]

Any non-numeric character following the back slash is taken literally. This allows you to search for things like the backslash character (by using \\ as a search term - literal character "\").

A slash followed by a number \00 is interpreted as the ASCII representation of that number (in this case NULL).

Using \x00 will look for "x00" (the x is taken as a literal).

I hope this clears up a little confusion.

Rob

[concorpoly]

But I searched <regular expression> entry in the Labview help file, <Special Characters for Match Regular Expression and Search and Replace String> page:

• \031 - Matches an octal character (31 octal in this case)
• \x3F - Matches a hexadecimal character (3F hexadecimal in this case)

[mikeporter · Accepted solution]

Yes but as I stated earlier that is a different function from the one you are using.

Mike...