What is the simplest way to create a mask for numbers in PHP?

Question

I have two ways to create masks for numbers in PHP, but I don’t know if it’s the most elegant and effective, so I would like to have some options to improve the code.

I need the function to behave as follows:

• Format numbers with less than 8 numbers by filling them with zero.
• Create a separator (can be a hyphen) in the middle of these 8 numbers. That is, 11112222 will transform into 1111-2222.

I already have these two examples:

Example 1:

implode('-', str_split(sprintf('%08s', $numero), 4));

Example 2

$formatado = sprintf('%08s', $numero);

substr($formatado, 0, 4) . '-' . substr($formatado, 4, 8);

Someone knows a better way, in terms of performance and elegance, without having to call multiple functions to create a PHP mask?

Answer 1

One way to solve this is to combine str_pad() to fill the left zeros* if the string is less than 8 characters long, chunk_split() to insert the hyphen every 4 characters and the Trim() to remove the added hyphene at the end.

<?php

function mascaraTelefone($numero){
    $numero = str_pad($numero, 8, '0', STR_PAD_LEFT);
    return trim(chunk_split($numero, 4, '-'), '-');
}

echo mascaraTelefone('9999') .PHP_EOL;
echo mascaraTelefone('99998888') .PHP_EOL;
echo mascaraTelefone('77') .PHP_EOL;
echo mascaraTelefone('666') .PHP_EOL;

Example - ideone

Based on: Insertion of a dot every 5 characters

A variant of this code is to exchange chunck_split() for substr_replace() replacing a copy of the character at position X(third argument) with the hyphen in the case.

function mascaraTelefone($numero){
    $numero = str_pad($numero, 8, '0', STR_PAD_LEFT);
    return substr_replace($numero, '-', 4, 0);
}

* The standard behavior of str_pad() is to add the characters to the right, this can be modified by informing the fourth argument of the function who possessed the values:

STR_PAD_RIGHT|Adiciona a direita(padrão caso o quarto argumento seja omitido
STR_PAD_LEFT |Adiciona a esquerda
STR_PAD_BOTH |Adiciona na esquerda e na direita

Answer 2

Generic formatting with dynamic mask:

function format_string($mask, $str, $ch = '#') {
    $c = 0;
    $rs = '';

    /*
    Aqui usamos strlen() pois não há preocupação com o charset da máscara.
    */
    for ($i = 0; $i < strlen($mask); $i++) {
        if ($mask[$i] == $ch) {
            $rs .= $str[$c];
            $c++;
        } else {
            $rs .= $mask[$i];
        }
    }

    return $rs;
}

$str = '05055344410'; // Exemplo para telefone
echo format_string('###-####-####', $str);
$str = '20150827'; // Exemplo para datas
echo '<br />' . format_string('####-##-##', $str);

Answer 3

It is already very well answered, but I would like to leave here a small technique that uses vsprintf and str_split together.

The function vsprintf is intended to format a string, based on past arguments. But different from sprintf, instead of passing n parameters, you pass a array. Therefore, we could use the function str_split to separate the strings and, with vsprintf, apply the formatting.

In this example, I passed a second argument to str_split, that will cause the string to be divided from 4 to 4, as is the case of phones.

function formatar_telefone($telefone) {
     return vsprintf('%s-%s', str_split($telefone, 4));
}

Of course there will be problems if the phone number does not contain 8 digits. Then in this case, it can be add a check inside the function, with a launch of an error or exception. Or just fill in the numbers with 0, as @rray suggested.

In that case, we could fill in sprintf to fill with zeros, using the expression %08d:

function formatar_telefone($telefone) {
     vsprintf('%s-%s%', str_split(sprintf('%08d', $telefone)));
}

The expression %08d means that you want to format a number, forcing it to be recognized as a digit, and if you have less than 8 characters, you will be filled with 0.