Regex - String should not include more than 7 digits

Question

Rules for String:

Can contain 0-7 digits

Test Cases :

abcd1234ghi567 ⟶ True
1234567abc ⟶ true
ab1234cd567 ⟶ true
abc12 ⟶ True
abc12345678 ⟶ False

How do I come up with a regular expression for the same?

The problem I am facing is - How to keep the count of digits in the whole string. The digits can occur any where in the string.

I would like a Pure regex solution

Check `"abc12345678".match(/\d/g).length` in an if statement. — akinuri, Mar 19 '16 at 01:05
@CasimiretHippolyte I wanted as a part of my json schema. Did not want to include my function. — suprita shankar, Mar 19 '16 at 01:16
i think this is what you are looking for: [Count the number of integers in a string \[regexp\]](http://stackoverflow.com/questions/7657824/count-the-number-of-integers-in-a-string) — cromerou, Mar 19 '16 at 01:18
If you want a pure regex solution that doesn't include any JavaScript code, you should explicitly mention it and not include the `JavaScript` tag in your question. — John Slegers, Mar 19 '16 at 11:10

John Slegers · Answer 1 · 2016-03-19T11:11:00.437

Approach 1

If you're OK with putting some of your logic in your JavaScript, something as simple as this function should do :

function validate(teststring) {
    return teststring.match(/\d/g).length < 8;
}

Demo

function validate(teststring) {
    return teststring.match(/\d/g).length < 8;
}

document.body.innerHTML =
    '<b>abcd1234ghi567 :</b> ' + validate('abcd1234ghi567') + '<br />' +
    '<b>1234567abc :</b> ' + validate('1234567abc') + '<br />'+
    '<b>ab1234cd567 :</b> ' + validate('ab1234cd567') + '<br />'+
    '<b>abc12 :</b> ' + validate('abc12') + '<br />'+
    '<b>abc12345678 :</b> ' + validate('abc12345678') + '<br />';

(see also this Fiddle)

Approach 2

If you prefer all of your logic to be in your regex instead of your JavaScript, you could use a regex like /^(\D*\d?\D*){7}$/ or /^([^0-9]*[0-9]?[^0-9]*){7}$/ and use RegExp.prototype.test() instead of String.prototype.match() to test your strings.

In that case, your validate function would look something like this :

function validate(teststring) {
    return /^([^0-9]*[0-9]?[^0-9]*){7}$/.test(teststring);
}

Demo :

function validate(teststring) {
    return /^([^0-9]*[0-9]?[^0-9]*){7}$/.test(teststring);
}

document.body.innerHTML =
    '<b>abcd1234ghi567 :</b> ' + validate('abcd1234ghi567') + '<br />' +
    '<b>1234567abc :</b> ' + validate('1234567abc') + '<br />'+
    '<b>ab1234cd567 :</b> ' + validate('ab1234cd567') + '<br />'+
    '<b>abc12 :</b> ' + validate('abc12') + '<br />'+
    '<b>abc12345678 :</b> ' + validate('abc12345678') + '<br />';

Thank you for the answer. I have added the answer below using regex only. Without having to using a function. Check it out. — suprita shankar, Mar 19 '16 at 01:21
Downvoting, because it doesn't fulfill the original requirement, which is a pure regex match. — Lenny Markus, Mar 19 '16 at 03:48
@LennyMarkus : The question at no time explicitly mentioned that a pure regex solution was required, and it contain the tag `JavaScript`. — John Slegers, Mar 19 '16 at 10:46
@LennyMarkus : Just for the sake of completeness, I added a second approach where the logic is put inside the regex only. — John Slegers, Mar 19 '16 at 11:06

suprita shankar · Accepted Answer · 2016-03-19T20:22:05.470

3

figured it out!

/^(\D*\d?\D*){0,7}$/

Every numeric char can be surrounded by non-numeric chars.

edited Mar 19 '16 at 20:22

answered Mar 19 '16 at 01:12

suprita shankar

1,554
2
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score 1 · Answer 3 · answered Mar 19 '16 at 02:32

The following regex can check if the total digits are less than 7:

var i, strings = ["abcd1234ghi567", "1234567abc", "ab1234cd567", "abc12", "abc12345678"];
for (i of strings) {
  document.write(i + " -> " + /^(?:[\D]*[0-9][\D]*){0,7}$/.test(i) + "</br>");
}

Regex - String should not include more than 7 digits

3 Answers3

Approach 1

Demo

Approach 2

Demo :