How to validate string in php

String validation

String validation – Validation for strings.

Introduction to String validation

This method validates string using the given format.

This method takes two arguments:

• String.
• An array of options.

Various option are:

• format (mixed) - Format of the string

  • VALIDATE_NUM - Number (0-9).
  • VALIDATE_SPACE - Space (\s).
  • VALIDATE_ALPHA_LOWER - Lower case alphabets (a-z).
  • VALIDATE_ALPHA_UPPER - Upper case alphabets (A-Z).
  • VALIDATE_ALPHA - Alphabets (a-Z).
  • VALIDATE_EALPHA_LOWER - Lower case letters with an accent (French, ...), umlauts (German), special characters (e.g. Skandinavian) and VALIDATE_ALPHA_LOWER.
  • VALIDATE_EALPHA_UPPER - Upper case letters with an accent (French, ...), umlauts (German), special characters (e.g. Skandinavian) and VALIDATE_ALPHA_UPPER.
  • VALIDATE_EALPHA - Letters with an accent (French, ...), umlauts (German), special characters (e.g. Skandinavian) and VALIDATE_ALPHA.
  • VALIDATE_PUNCTUATION - Punctuation .,;:&"?!', "(" and ")".
  • VALIDATE_NAME - VALIDATE_EALPHA, VALIDATE_SPACE, "'" and "-".
  • VALIDATE_STREET - VALIDATE_NUM and VALIDATE_NAME, "\./", "º" and "ª".
• min_length (int) - Minimum length.
• max_length (int) - Maximum length.

How to use String Validation

String Validation

The following example assumes that one wants to validate a string when only uppercase alphabets, numbers and space are allowed

require_once 'Validate.php';

if (

I am trying to verify in PHP with preg_match that an input string contains only "a-z, A-Z, -, _ ,0-9" characters. If it contains just these, then validate.

I tried to search on google but I could not find anything usefull.

Can anybody help?

Thank you !

asked Dec 27, 2012 at 15:10

1

Use the pattern '/^[A-Za-z0-9_-]*$/', if an empty string is also valid. Otherwise '/^[A-Za-z0-9_-]+$/'

So:

$yourString = "blahblah";
if (preg_match('/^[A-Za-z0-9_-]*$/', $yourString)) {
    #your string is good
}

Also, note that you want to put a '-' last in the character class as part of the character class, that way it is read as a literal '-' and not the dash between two characters such as the hyphen between A-Z.

answered Dec 27, 2012 at 15:12

DWrightDWright

9,1884 gold badges35 silver badges53 bronze badges

2

$data = 'abc123-_';
echo preg_match('/^[\w|\-]+$/', $data); //match and output 1

$data = 'abc..';
echo preg_match('/^[\w|\-]+$/', $data); //not match and output 0

answered Dec 27, 2012 at 15:18

LevinLevin

1945 bronze badges

You can use preg_replace($pattern, $replacement, $subject):

if (preg_replace('/[A-Za-z0-9\-\_]/', '', $string)) {
  echo "Detect non valid character inside the string";
}

The idea is to remove any valid chars, if the result is NOT empty do the code.

answered Jul 5, 2018 at 12:08

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