If text contains word

You could use regular expressions as it’s better for word matching compared to strpos, as mentioned by other users. A strpos check for are will also return true for strings such as: fare, care, stare, etc. These unintended matches can simply be avoided in regular expression by using word boundaries.

A simple match for are could look something like this:

$a = 'How are you?';

if (preg_match('/bareb/', $a)) {
    echo 'true';
}

On the performance side, strpos is about three times faster. When I did one million compares at once, it took preg_match 1.5 seconds to finish and for strpos it took 0.5 seconds.

Edit:
In order to search any part of the string, not just word by word, I would recommend using a regular expression like

$a = 'How are you?';
$search = 'are y';
if(preg_match("/{$search}/i", $a)) {
    echo 'true';
}

The i at the end of regular expression changes regular expression to be case-insensitive, if you do not want that, you can leave it out.

Now, this can be quite problematic in some cases as the $search string isn’t sanitized in any way, I mean, it might not pass the check in some cases as if $search is a user input they can add some string that might behave like some different regular expression…

Also, here’s a great tool for testing and seeing explanations of various regular expressions Regex101

To combine both sets of functionality into a single multi-purpose function (including with selectable case sensitivity), you could use something like this:

function FindString($needle,$haystack,$i,$word)
{   // $i should be "" or "i" for case insensitive
    if (strtoupper($word)=="W")
    {   // if $word is "W" then word search instead of string in string search.
        if (preg_match("/b{$needle}b/{$i}", $haystack)) 
        {
            return true;
        }
    }
    else
    {
        if(preg_match("/{$needle}/{$i}", $haystack)) 
        {
            return true;
        }
    }
    return false;
    // Put quotes around true and false above to return them as strings instead of as bools/ints.
}

One more thing to take in mind, is that b will not work in different languages other than english.

The explanation for this and the solution is taken from here:

b represents the beginning or end of a word (Word Boundary). This
regex would match apple in an apple pie, but wouldn’t match apple in
pineapple, applecarts or bakeapples.

How about “café”? How can we extract the word “café” in regex?
Actually, bcaféb wouldn’t work. Why? Because “café” contains
non-ASCII character: é. b can’t be simply used with Unicode such as
समुद्र, 감사, месяц and 😉 .

When you want to extract Unicode characters, you should directly
define characters which represent word boundaries.

The answer: (?<=[s,.:;"']|^)UNICODE_WORD(?=[s,.:;"']|$)

So in order to use the answer in PHP, you can use this function:

function contains($str, array $arr) {
    // Works in Hebrew and any other unicode characters
    // Thanks https://medium.com/@shiba1014/regex-word-boundaries-with-unicode-207794f6e7ed
    // Thanks https://www.phpliveregex.com/
    if (preg_match('/(?<=[s,.:;"']|^)' . $word . '(?=[s,.:;"']|$)/', $str)) return true;
}

And if you want to search for array of words, you can use this:

function arrayContainsWord($str, array $arr)
{
    foreach ($arr as $word) {
        // Works in Hebrew and any other unicode characters
        // Thanks https://medium.com/@shiba1014/regex-word-boundaries-with-unicode-207794f6e7ed
        // Thanks https://www.phpliveregex.com/
        if (preg_match('/(?<=[s,.:;"']|^)' . $word . '(?=[s,.:;"']|$)/', $str)) return true;
    }
    return false;
}

As of PHP 8.0.0 you can now use str_contains

<?php
    if (str_contains('abc', '')) {
        echo "Checking the existence of the empty string will always"
        return true;
    }

Home » Check If A String Contains A Specific Word In PHP

Last updated on December 24, 2020 by

Topic: PHP / MySQLPrev|Next

Answer: Use the PHP strpos() Function

You can use the PHP strpos() function to check whether a string contains a specific word or not.

The strpos() function returns the position of the first occurrence of a substring in a string. If the substring is not found it returns false. Also note that string positions start at 0, and not 1.

Let’s check out an example to understand how this function basically works:

<?php
$word = "fox";
$mystring = "The quick brown fox jumps over the lazy dog";
 
// Test if string contains the word 
if(strpos($mystring, $word) !== false){
    echo "Word Found!";
} else{
    echo "Word Not Found!";
}
?>

Related FAQ

Here are some more FAQ related to this topic:

• How to count how many times a substring occurs in a string in PHP
• How to replace a word inside a string in PHP
• How to split a string into an array in PHP

Check for existence of a substring into a string is a common requirement for programmers. Here I’m describing 3 functions to check if string contains specific words.

The top 3 functions available in PHP to check for word existence are:

• strpos – Find the position of the first occurrence of a substring in a string.
• strstr – Find the first occurrence of a string
• preg_match – Perform a regular expression match

Each of them has variations for case-insensitive search, last occurrence etc. We are taking ‘strpos‘ into account as it’s faster and enough to find occurrence.

Check if string contains specific words

Suppose we have the requirement below:

Then the correct way to write the statement will be: 

Note that the use of !== false is deliberate as if the needle (‘$word‘) you are searching for is at the beginning of the haystack (‘$sentence‘), it will return position 0. Since 0 is a valid offset and 0 is ‘falsey‘, we can’t use simpler constructs like !strpos($sentence, $word).

If you want to check if a string does not contain a word then rather changing ‘false‘ to ‘true‘, use complementary operator ‘===‘ like strpos($sentence, $word) === false.

Be aware that this will also return true for the string ‘Do you care?‘. If you need to deal with this situation then you can check the substring or word by either improving ‘strpos‘ condition or using ‘preg_match‘.

The ‘preg_match‘ above will get fail with  sentences which are going to be anything that isn’t a-z, A-Z, 0-9, or _. That means digits and underscores are going to be counted as word characters and scenarios like these will return false:

• The ‘are’ at the beginning of ‘area’
• The ‘are’ at the end of ‘hare’
• The ‘are’ in the middle of ‘fares’
• The ‘are’ in ‘What _are_ you thinking?’
• The ‘are’ in ‘lol u dunno wut those are4?’

The preg_match is slower and is not recommended to just check if string contains specific words.