How to make a regular expression for mobile phone?

Question

How to create a regular expression to validate the phone field you accept 99-99999999 (DDD + 8 numbers) or 99-999999999 (DDD + 9 numbers). And that when typing it add the dash - automatically!

ValidationExpression="^[0-9]{2}-([0-9]{8}|[0-9]{9})"

How to proceed?

Answer 1

Nowadays all mobile phones in Brazil have nine digits and start with digit 9 and all fixed phones have 8 digits and never start with digit 9. I would personally prefer to format the phone as (xx) xxxxx-xxxx. So the best regular expression for this would be this:

^\([1-9]{2}\) (?:[2-8]|9[1-9])[0-9]{3}\-[0-9]{4}$

Her full explanation is:

• ^ - String start.
• \( - One parentheses.
• [1-9]{2} - Two digits from 1 to 9. No DDD codes with digit 0.
• \) - A close parenthesis.
• - A blank space.
• (?:[2-8]|9[1-9]) - The beginning of the number. Represents a choice between the one digit between 2 and 8 (the part of [2-8]) and a 9 followed by a digit from 1 to 9 (the part of the 9[1-9]). The | separates the options to be chosen. O (?: ... ) groups such choices. Fixed phones start with digits from 2 to 8. Mobile phones start with 9 and have a second digit from 1 to 9. The first digit will never be 0 or 1. Mobile phones can’t start with 90 because this is the prefix for collect calls.
• [0-9]{3} - The remaining three digits of the first half of the phone number, making a total of 4 or 5 digits in the first half.
• \- - A hyphen.
• [0-9]{4} - The second half of the phone number.
• $ - String end.

If you want to leave the parentheses, blank space and hyphen optional, then you can put a ? after each of these symbols, resulting in this regular expression:

^\(?[1-9]{2}\)? ?(?:[2-8]|9[1-9])[0-9]{3}\-?[0-9]{4}$

---

If you want, you can also filter the Ddds that exist. Here’s an image that shows the current area codes according to the Wikipedia:

Looking at this map, the subexpression that would filter the valid Ddds would be as follows:

(?:[14689][1-9]|2[12478]|3[1234578]|5[1345]|7[134579])

As explained above, the (?: ... ) is to group. The options (separated by |) would be two-digit groups, which would be one of the following options: 2[12478] to Rio de Janeiro and Espírito Santo, 3[1234578] to Minas Gerais, 5[1345] to Rio Grande do Sul, 7[134579] to Bahia and Sergipe and [14689][1-9] for the rest of Brazil.

And the complete regular expression would be as follows (with the mandatory parentheses, spaces and hyphens):

^\((?:[14689][1-9]|2[12478]|3[1234578]|5[1345]|7[134579])\) (?:[2-8]|9[1-9])[0-9]{3}\-[0-9]{4}$

And with them not obligatory:

^\(?(?:[14689][1-9]|2[12478]|3[1234578]|5[1345]|7[134579])\)? ?(?:[2-8]|9[1-9])[0-9]{3}\-?[0-9]{4}$

---

^{_{NOTE: This answer was originally written in 2015, when there were 8 or 9 digit cell phones, depending on the area code. Since then, it has been upgraded to the newest format in effect, which always has 9 digits. If you want more details on how this response was edited, check out the edition history.}}

Answer 2

My solution may not be the most effective, but as I did not see many solutions commenting on some points I decided to write my.

I created a regular expression that identifies whether a string is a phone, taking into account the following cases:

• Telephones 0800
• Operator numbers and services like 10315 and 190
• Telephones represented with or without parentheses
• Accepts carrier represented as 0xx11
• Phones with or without tabs [ .-]
• Ignore phones starting with 0 if you do not have DDD (ex: 0999-9999 is not accepted, but 0xx11 9123-1234 is)

It got a little big and difficult to read humanly, but it attends my projects:

/^1\d\d(\d\d)?$|^0800 ?\d{3} ?\d{4}$|^(\(0?([1-9a-zA-Z][0-9a-zA-Z])?[1-9]\d\) ?|0?([1-9a-zA-Z][0-9a-zA-Z])?[1-9]\d[ .-]?)?(9|9[ .-])?[2-9]\d{3}[ .-]?\d{4}$/gm

You can see the expression in use at this link.

After validating whether the expression is a phone, you can format it the way you think best by manipulating the string.

Here is an example in Java (where PHONE_MATCH is the regular expression):

public String phone(String phoneString) throws IllegalArgumentException {
    if (!phoneString.matches(PHONE_MATCH)) {
        throw new IllegalArgumentException("Not a valid phone format");
    }

    String str = phoneString.replaceAll("[^\\d]", "");

    if (str.charAt(0) == '0') {
        if (str.charAt(1) == '0') {
            str = str.substring(2);
        } else {
            str = str.substring(1);
        }
    }

    switch (str.length()) {
        case 8:
            return applyMask(str, "AAAA-AAAA", 'A');
        case 9:
            return applyMask(str, "AAAAA-AAAA", 'A');
        case 10:
            return applyMask(str, "(AA) AAAA-AAAA", 'A');
        case 11:
            return applyMask(str, "(AA) AAAAA-AAAA", 'A');
        default:
            return str;
    }
}

ApplyMask method:

public String applyMask(String str, String mask, char specialChar) {

    // Conta quantos caracteres especiais existem na máscara
    int maskChCount = mask.length() - mask.replaceAll("[^" + specialChar + "]", "").length();

    // Conta apenas os números
    int strChCount = str.length() - str.replaceAll("\\d", "").length();

    // Exceção caso a string nao tenha números suficientes para competar a máscara
    if (strChCount < maskChCount) {
        throw new IllegalArgumentException("The number of chars in the string should not be smaller than the " +
                "number of special chars in the mask");
    }

    char[] maskChars = mask.toCharArray();
    char[] strChars = str.toCharArray();

    // Itera por todos os elementos da máscara
    for (int i = 0, j = 0; i < maskChars.length && j < strChars.length; i++) {
        char ch = maskChars[i];
        char sh = strChars[j];

        if (ch == specialChar) {
            // Se achou o caractere especial, buscar o próximo elemento aceito da String e 
            // substituí-lo no local do caractere especial
            while (!Character.toString(sh).matches("\\d")) {
                j++;
                sh = strChars[j];
            }
            maskChars[i] = sh;
            j++;
        }
    }

    return new String(maskChars);
}

I believe you have several ways to optimize this code, any suggestion is welcome.

Answer 3

I use this

@"^\(?\d{2}\)?[\s-]?[\s9]?\d{4}-?\d{4}$"

If you put 9 digits it forces you that the first digit is 9.

I would take a little of each example to assemble the ideal.

Answer 4

Guys, with your help I created a string that I thought was ideal for me. Simple and direct. In WHMCS use to start and close /. I will not use in the example to follow your example. Come on. The expression looks like this:

^\([1-9]{2}\) [9]{0,1}[6-9]{1}[0-9]{3}\-[0-9]{4}$

Explanation:

• ^ = String start.
• \( = One parentheses.
• [1-9]{2} = Two digits from 1 to 9. No DDD codes with digit 0.
• \) = A close parenthesis.
• = A blank space.
• [9]{0,1} = The first digit is 9, plus it may or may not exist hence the "0" or "1" within the {0.1}.
• [6-9]{1} = the second digit can be 6 to 9.
• [0-9]{3} = The three other digits are 0 to 9
• \- = A hyphen.
• [0-9]{4} = The second half of the phone number.
• $ = String end.

Remembering friends that at WHMCS should start and close with /. By the end of 2016 or more precise in November 6, 2016 all Brazil will have the 9 at the beginning of cell phones.

Answer 5

^\([1-9]{2}\) 9[7-9]{1}[0-9]{3}\-[0-9]{4}$

• [1-9]{2} = Two digits from 1 to 9. No DDD with digit 0.
• 9 = All cell phones from 2016 start by 9
• [7-9]{1} = In the old numbering the phones started with 7, 8 or 9
• [0-9]{3} = The three other digits can be from 0 to 9
• [0-9]{4} = The four after the hyphen can be 0 to 9