How to check if the Term is contained in String in PHP?

Question

I need to check if a certain tag is inside the string. I get this string from the database that comes in the form of tags comma separated without spaces as below:

String

canais,proteses,implantes

Term

proteses

How to check with PHP if Termo is contained within String?

Answer 1

This can be done as follows with regular expression in PHP:

<?php

$tags = 'canais,proteses,implantes';
$termo = 'proteses';

$pattern = '/' . $termo . '/';//Padrão a ser encontrado na string $tags
if (preg_match($pattern, $tags)) {
  echo 'Tag encontrada';
} else {
  echo 'Tag não encontrada';
}

Or also using the functions explode and in_array as follows:

<?php

$tags = 'canais,proteses,implantes';
$tagsArray = explode(',', $tags);
$termo = 'proteses';

if (in_array($termo, $tagsArray)) {
  echo 'Tag encontrada';
} else {
  echo 'Tag não encontrada';
}

Or as follows:

<?php

$tags = 'canais,proteses,implantes';
$tagsArray = explode(',', $tags);
$termo = 'proteses';

$count = 0;
foreach ($tagsArray as $tag) {
  if ($tag == $termo) {
    $count++;
  }
}

if ($count > 0) {
  echo 'Tag encontrada';
} else {
  echo 'Tag não encontrada';
}

Answer 2

Just use the function strpos (or mb_strpos for strings non-sascii):

$palheiro = 'canais,proteses,implantes';
$agulha   = 'proteses';

$pos = strpos( $palheiro, $agulha );

// exemplo de uso:

if ($pos === false) {
   echo 'Não encontrado';
} else {
   echo 'Encontrado';
}

The function strpos returns false when the string is not found, and if found, its numerical position.

Important to note that if the string is found at the beginning of the line, the return will be 0, so we have to use type comparison ( === or !== ) to differentiate the false of 0.

Other examples of syntax:

$encontrado = ( strpos( $palheiro, $agulha ) !== 0 );

if ($encontrado) {
   echo 'Encontrado';
} else {
   echo 'Não encontrado';
}

$pos = strpos( $palheiro, $agulha );
if ( $pos !== false) echo 'encontrei!';

$pos = strpos( $palheiro, $agulha );
$encontrei = ( $pos !== false ) ? 'sim' : 'não';

Tips:

If your application is to work with variable data, it is best to secure and use a format that does not give side effects if you have similar words.

For example:

$palheiro = 'carro,moto,ciclomotor';
$agulha = 'moto';
// encontrado!

$palheiro = 'carro,ciclomotor';
$agulha = 'moto';
// encontrado! Opa! Peraí???

This is because the word "moped" contains "motorcycle".

The solution:

To not need to use more complex functions, just use a little trick:

$palheiro = 'carro,moto,ciclomotor';
$agulha = 'moto';
$pos = strpos( ','.$palheiro.',', ','.$agulha.',' );
// encontrado!

$palheiro = 'carro,ciclomotor';
$agulha = 'moto';
$pos = strpos( ','.$palheiro.',', ','.$agulha.',' );
// não encontrado!

The explanation is simple: adding the commas on the "tips" of the two strings, crunching ,moto,inside ,carro,ciclomotor, and eliminating ambiguities, without needing to appeal to more complex functions.

strips()

As well remembered by @Danielomine, if you want to find the words regardless of whether they are uppercase or lowercase, you can use the functions case insensitive stripos() and mb_stripos() (various functions of PHP have version with and without the i, which is precisely from insensitive). Note that these internal functions are limited in relation to accentuation.

Using with DB

If this data is coming from a database, you can filter this directly into the SELECT, we have some examples here on the site.