How to check, if a php string contains only english letters and digits?

Question

In JS I used this code:

if(string.match(/[^A-Za-z0-9]+/))

but I don't know, how to do it in PHP.

Maxime Pacary · Accepted Answer · 2014-09-24T12:21:02.603

108

Use preg_match().

if (!preg_match('/[^A-Za-z0-9]/', $string)) // '/[^a-z\d]/i' should also work.
{
  // string contains only english letters & digits
}

edited Sep 24 '14 at 12:21

answered Feb 19 '12 at 17:19

Maxime Pacary

22,336
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5

yes. it looks more efficient. To look for the first non-in-range character seems more sensible than scanning whole string. – Your Common Sense Feb 19 '12 at 17:23
N.B english verison of above link here: http://php.net/manual/en/function.preg-match.php – Phillip Macdonald Sep 23 '14 at 10:22
1

I just tried this and the use of the ! operator gives wrong results. The code inside the if statement will be executed if the string does not contain only english letters & digits. – chap Oct 31 '17 at 02:44
@chap could you please provide an example of "non working" string ? – Maxime Pacary Nov 01 '17 at 14:27
1

For example if I give the string "{}\" the code inside your if statement will execute. But your comment inside the if statement // string contains only english letters & digits indicates that you want the code inside the if statement to execute only if the string contains a-z A-Z or 0-9, however by using the ! your code does the opposite. – chap Nov 02 '17 at 00:30
1

@chap did you see the ^ char at the beginning of the regex? It means that as soon as an "invalid" char is found, preg_match() returns true. Without the !, the if block would be executed for any "invalid" string. I will retest the whole thing ASAP however & will keep you informed. – Maxime Pacary Nov 02 '17 at 08:30
@FrostyZ you are right. I didn't know that the ^ negated the rest of the expression, so I didn't understand why I was getting the result. But now I know it makes perfect sense. Sorry. – chap Nov 02 '17 at 22:31
Where is the space included in regex – santanu bera Mar 12 '20 at 13:13

score 34 · Answer 2 · edited Nov 02 '13 at 18:37

34

if(ctype_alnum($string)) {
    echo "String contains only letters and numbers.";
}
else {
    echo "String doesn't contain only letters and numbers.";
}

edited Nov 02 '13 at 18:37

Ryan

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15

answered Dec 04 '12 at 03:41

vineeth

357
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2

Not sure why people are not voting the ctype function. I can't imaging there is a performance issue with the range of ctype functions. – Ryan Bayne Sep 06 '14 at 20:05
4

ctype_alnum are locale depended so it might not work as you wish ! – thethakuri Jun 03 '16 at 14:38

score 12 · Answer 3 · edited Jul 14 '17 at 12:39

12

if you need to check if it is English or not. you could use below function. might help someone..

function is_english($str)
{
    if (strlen($str) != strlen(utf8_decode($str))) {
        return false;
    } else {
        return true;
    }
}

edited Jul 14 '17 at 12:39

Alex Tartan

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answered Nov 04 '15 at 17:11

shakee93

4,976
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score 11 · Answer 4 · answered Feb 19 '12 at 17:19

11

You can use preg_match() function for example.

if (preg_match('/[^A-Za-z0-9]+/', $str))
{
  // ok...
}

answered Feb 19 '12 at 17:19

evilone

22,410
7
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107

score 7 · Answer 5 · edited Jul 14 '17 at 12:39

7

Have a look at this shortcut

if(!preg_match('/[^\W_ ] /',$string)) {

}

the class [^\W_] matches any letter or digit but not underscore . And note the ! symbol . It will save you from scanning entire user input .

edited Jul 14 '17 at 12:39

Alex Tartan

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answered Feb 19 '12 at 17:50

HalfWebDev

7,022
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65
103

score 5 · Answer 6 · answered Feb 19 '12 at 17:20

5

if(preg_match('/[^A-Za-z0-9]+/', $str)) {
    // ...
}

answered Feb 19 '12 at 17:20

Vitamin

1,526
1
13
27

score 2 · Answer 7 · answered Sep 05 '18 at 09:22

2

if (preg_match('/^[\w\s?]+$/si', $string)) {
    // input text is just English or Numeric or space
}

answered Sep 05 '18 at 09:22

Ramin Rabiee

21
1

1

It depends on locale. For me (French, locale fr_fr) `\w` matches all characters with diacritic like `éèçàÀ...` – Toto Sep 05 '18 at 12:06

score 1 · Answer 8 · answered Apr 05 '19 at 18:44

if(preg_match('/^[A-Za-z0-9]+$/i', $string)){ // '/^[A-Z-a-z\d]+$/i' should work also
// $string constains both string and integer
}

The carrot was in the wrong place so it would have search for everything but what is inside the square brackets. When the carrot is outside it searches for what is in the square brackets.

score 0 · Answer 9 · edited Oct 10 '17 at 16:07

0

PHP can compare a string to a regular expression using preg_match(regex, string) like this:

if (!preg_match('/[^A-Za-z0-9]+/', $string)) {
    // $string contains only English letters and digits
}

edited Oct 10 '17 at 16:07

Adam Katz

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answered Oct 10 '17 at 13:48

Saurabh

1
1

score -1 · Answer 10 · answered May 29 '21 at 19:47

The following code will take care about special characters and spaces

$string = 'hi, how are you ?';
if (!preg_match('/[^A-Za-z0-9 #$%^&*()+=\-\[\]\';,.\/{}|":<>?~\\\\]+/', $string)) // '/[^a-z\d]/i' should also work.
{
    echo 'english';
}else
{
    echo 'non-english';
}

How to check, if a php string contains only english letters and digits?

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