Search for a string inside another string in PHP

• Checking if a string contains another string or substring in PHP
• str_contains(): PHP 8+ (Simplest and Most Readable)
• strpos() (and stripos()): Widely Supported Alternative
• preg_match(): When You Need Pattern Power
• strstr(): Simpler Alternative to Locate and Return the Remaining String
• Choosing the Right Tool: At a Glance
• Example: Testing Multiple Methods
• Final Thoughts

Checking if a string contains another string or substring in PHP

When working with PHP, determining whether a string contains another string or substring is a common and foundational task. In this post, we’ll explore several reliable methods each with their own benefits so you can choose the one that fits your needs best.

str_contains(): PHP 8+ (Simplest and Most Readable)

Starting with PHP 8, str_contains() is the most straightforward way to check if one string appears within another:

if (str_contains($haystack, $needle)) {
    echo "Found!";
} else {
    echo "Not found.";
}

• Returns true if $needle exists within $haystack, otherwise false.
• Clean syntax and readability.
• Important caveat: If $needle is an empty string, str_contains() always returns true so ensure you validate that $needle isn’t blank if that’s not desired.

strpos() (and stripos()): Widely Supported Alternative

For earlier PHP versions (pre‑8) or for more control over how matches are detected, strpos() is a classic approach:

if (strpos($haystack, $needle) !== false) {
    echo "Found!";
}

• Returns the 0‑based index of the first occurrence if found, or false if not.
• Important: Must compare with !== false, not just truthiness, because 0 is a valid position.
• stripos() is the case‑insensitive version, returning the same type of result.

preg_match(): When You Need Pattern Power

If you need more sophisticated matching like full‑word boundaries or complex patterns preg_match() with regular expressions is your go-to:

if (preg_match('/example/', $string)) {
    echo "Found!";
}

• Supports regex, so you can handle edge cases like matching whole words only, case‑insensitively, and more.
• Add the i flag for case‑insensitive search.

For instance, to match the whole word "joe" and avoid "joey", a regex like \bjoe\b works perfectly.

strstr(): Simpler Alternative to Locate and Return the Remaining String

If all you need is part of the string from the match onward, strstr() is a neat choice:

$result = strstr($string, $needle);
if ($result !== false) {
    // $result contains substring from $needle to end
}

• Returns the matched part and onwards, or false if not found.

Choosing the Right Tool: At a Glance

Example: Testing Multiple Methods

Here’s a quick example showcasing each method:

$haystack = "The quick brown fox jumps over the lazy dog";
$needle   = "fox";
 
// 1. str_contains (PHP 8+)
echo str_contains($haystack, $needle) ? "Found via str_contains\n" : "Not found\n";
 
// 2. strpos (case‑sensitive)
if (strpos($haystack, $needle) !== false) {
    echo "Found via strpos\n";
}
 
// 3. stripos (case‑insensitive)
if (stripos($haystack, strtoupper($needle)) !== false) {
    echo "Found via stripos\n";
}
 
// 4. preg_match (whole word, case‑insensitive)
if (preg_match('/\\bfox\\b/i', $haystack)) {
    echo "Found via preg_match (whole word)\n";
}
 
// 5. strstr
if (strstr($haystack, $needle) !== false) {
    echo "Found via strstr. Substring is: " . strstr($haystack, $needle);
}

Final Thoughts

• The modern, cleanest option is str_contains(), ideal when using PHP 8 or newer.
• For compatibility or when you need position data, strpos() remains reliable.
• Don’t hesitate to reach for preg_match() when you need full regex control or whole‑word matching.
• Always handle edge cases like empty needles or case differences wisely.