用于数字，逗号，下划线，斜杠，连字符和空格的PHP正则表达式

Question

I need a string which consists of some numbers, comma, undersocre, slash, hyphen and space.

I am almost ok. Here is my code so far.

$regex = '#^[0-9-_,/\s]+$#';
if(preg_match($regex, $string)){
    return true;
} else {
    return false;
}

But I want to contain at least 4 digit within 0 to 9.

for example, These are the values I want to valid:

09-12345678
123, 456, 789
12/ 34/ 56

These are the values I don't want to valid:

1,2
3/5/6
7-8-9

So, I tried like this.

$regex = '#^[0-9-_,/\s]{4,100}$#';

And,

$regex = '#^[0-9{4,100}-_,/\s]+$#';

But they are not true too. How can I do?

Answer 1

You can use a lookahead based regex:

~^(?=(?:\D*\d){4})[-0-9_,/\s]+$~

RegEx Demo

• (?=(?:\D*\d){4}) is lookahead to assert presence of at least 4 digits in input.
• Also important is to keep hyphen at start or end in character class [...]