Regex.IsMatch Issues

Question

This should be a fairly simple question, but I seem to be overthinking it.

I have an input that I need to make sure does not have any characters that are not ASCII printable characters (character code 32-127).

string someString = "6244ABº¿º";
var regexPattern = new Regex("^$|[ -~]*");

if (regexPattern.IsMatch(someString))
{
   //invalid format
}

Here's an idea of what I want as inputs and outputs:

Input: AB2RAF@#%$@%  Ouput: Valid (All are within ASCII 32-127)
Input: º¿º234234     Ouput: Invalid (Has 'º' and '¿')
Input: AAABCC        Ouput: Valid

Edit: I think it's the regex that's backwards. It has something to do with the '*'?

Do you consider ASCII 127 invalid? Or code does, but your description does not. — CodesInChaos, Jan 10 '17 at 15:11
You could negate the meaning of the regex (so it matches if the input is valid) and go with `^[ -~]*$` — CodesInChaos, Jan 10 '17 at 15:12
Empty is still valid. Good point, ASCII 127 wouldn't be valid then. — ferensilver, Jan 10 '17 at 15:13
Possible duplicate of [Regex any ascii character](http://stackoverflow.com/questions/3203190/regex-any-ascii-character) — Maksim Simkin, Jan 10 '17 at 15:17

Mats391 · Accepted Answer · 2017-01-10T15:36:32.893

4

I would just iterate the characters of your string and check if any is outside your desired range. Something like

private bool IsPrintable(string someString)
{
    foreach(var c in someString)
    {
        if((int)c < 32 || (int)c > 127)
            return false;
    }
    return true;
}

edited Jan 10 '17 at 15:36

answered Jan 10 '17 at 15:08

Mats391

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A simpler but slower version would be `!s.Any(c => c < 32 || c > 127)` or ``s.All(c => c >= 32 && c <= 127)`` – CodesInChaos Jan 10 '17 at 15:10
Thanks! This seems to do the trick! I did run into some syntax issues with your code (one extra ')' at the end of the if statement. – ferensilver Jan 10 '17 at 15:25

Wagner DosAnjos · Answer 2 · 2017-01-10T15:08:51.983

1

Please try the following:

string someString = "6244ABº¿º";
var regexPattern = new Regex("^$|[^ -~]");

if (regexPattern.IsMatch(someString))
{
   //invalid format
}

I added ^ to negate the character range -~, so any character outside that range will match the expression. I also removed the * as it's not necessary (just a single non-printable character is enough for the string to be invalid).

edited Jan 10 '17 at 15:08

answered Jan 10 '17 at 15:05

Wagner DosAnjos

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You should add an explanation of what you changed and why. – CodesInChaos Jan 10 '17 at 15:06

Ghasan غسان · Answer 3 · 2017-01-10T16:13:16.157

0

Mats391 is the straight forward answer for your question if you only want the range from 32 to 127. However, if you just want to ensure that no control character is present only (if you want to include Unicode characters, for example), then this might be what you are looking for.

string someString = "6244ABº¿º";
bool isValid = someString.All(i => !Char.IsControl(i));

edited Jan 10 '17 at 16:13

answered Jan 10 '17 at 15:24

Ghasan غسان

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Regex.IsMatch Issues

3 Answers3