Regular expression for a non-zero hex value

Question

Regular expression for a non-zero hex value

I am looking for a regular expression to determine when any of the values in a 32-bit hex value is non-zero.

The data patterns look like 0x00000000 and I want to know when any of the digits is non-zero. For example, if 0x00001000 or 0x10000000 or 0xB000000 would be capture by the regular expression, but not a 0x00000000 pattern. Right now I perform a walking pattern match of

0x[^0]
0x0[^0]
0x00[^0]
...
0x0000000[^0]

This will work, but I much rather have one pattern if possible. Thanks.

Mark

Edit: I didn't mention as the RegEx was not needed in a program, otherwise I would have used a different approach, but I was using the RegEx to search for values in a log file using UltraEdit. I could have developed a program or some other means to search, but I was just being lazy, just being honest. Ben S solution worked both in UltraEdit and Rad Software Regular Expression Designer. rampion solution didn't work in either tool, not sure why.

regex

hex

asked on Stack Overflow Apr 17, 2009 by

lordhog • edited Apr 17, 2009 by

lordhog

8 Answers

Why not test the hex value against zero? Simpler, faster, more readable.

If a regular expressiong is really necessary, 0x0*[1-9a-fA-F][0-9a-fA-F]* should do it.

It looks for as many zeros as it can until it finds a non-zero hex value, then gathers the rest of the hex regardless of if it's a zero or not.

Note: this will match any length hex, not just 32 bits.

answered on Stack Overflow Apr 17, 2009 by

Ben S • edited Apr 17, 2009 by

Ben S

/0x0*[1-9a-fA-F][0-9a-fA-F]*/

<atom>* means match the atom 0 or more times, so this pattern matches the 0x prefix, followed by 0 or more 0s, followed by a non-zero hex, followed by some hex.

answered on Stack Overflow Apr 17, 2009 by

rampion

Why not try something slighly different. Testing for a non-zero hex is much harder than testing for a zero hex. So test for zero and manually do the not.

bool IsNonZeroHex(string input) {
  return !Regex.IsMatch(input, "^0x(0*)$");
}

answered on Stack Overflow Apr 17, 2009 by

JaredPar

/0x0*[^0]/

answered on Stack Overflow Apr 17, 2009 by

chaos

Fixed size hex numbers can be looked up using negative lookahead as:

/(0x(?!0{8})[0-9a-fA-F]{8})/

A group is looked up beginning with 0x

then negative look ahead 0{8} (fails if found)

otherwise match [0-9a-fA-F]{8}

Works with PCRE, JavaScript, Python. Don't know which editors support negative lookahead.

answered on Stack Overflow May 30, 2019 by

Štefan Petrucha

Surely a simple string compare and if it DOES NOT EQUAL "0x00000000" you've got your match.

Am I over simplifying it? The is only one FALSE case, right? When the string is "0x00000000"?

Don't use RegEx unless you have to.

answered on Stack Overflow Apr 17, 2009 by

rjstelling

I think this should cover all cases (if it really has to be a regex):

^0x(?=0*[1-9a-fA-F]0*)[0-9a-fA-F]{8}$

answered on Stack Overflow Apr 17, 2009 by

dr Hannibal Lecter

/0x0{0,7}[^0]/

'0x', followed by zero to seven '0', followed by something that is not '0'

answered on Stack Overflow Apr 17, 2009 by

Brad Gilbert

User contributions licensed under CC BY-SA 3.0