Searching for words inside a string by using stristr & strstr function

Find the first matching substring with strstr()

strstr() returns the part of the haystack beginning with the first match, or false when the needle is absent. Use a strict false check when the result controls program logic. If you only need a yes/no existence check, str_contains() is clearer for current PHP.

$text = 'Learn PHP strings';
$match = strstr($text, 'PHP');
if ($match !== false) {
    echo $match; // PHP strings
}

Use strstr() when you need the substring starting at the first case-sensitive match. Check for false before using the result.

$haystack="myuserid@example.com";
$needle="@";
echo strstr($haystack,$needle,false);// @example.com

Output is

@example.com

Syntax

echo strstr($haystack,$needle,$before);

$haystack

Required: Input string ( main string for searching )

$needle

Required: used to search the first occurrence inside Input string

$before

Optional: default FALSE, if set to TRUE then output returns the string before the first occurrence of $needle ( excluding the $needle )

Output is the part of string after the needle ( if $before is FALSE ) or before the needle. FALSE is returned if matching is not found.

This is case sensitive search. Use stristr() for case in-sensitive search

$haystack="myuserid@example.com";
$needle="@";
echo strstr($haystack,$needle,true);// myuserid

Output is

myuserid

Example of strstr()

$haystack="Welcome to plus2net.com to learn PHP";
$needle="to";
echo strstr($haystack,$needle);// to plus2net.com to learn PHP

Output is

to plus2net.com to learn PHP

When to use strstr()

strstr() extracts the suffix beginning at the first case-sensitive match. To extract an email domain after validating the address, search for @:

$email = 'myname@example.com';
$at = strstr($email, '@');
if ($at !== false) {
    echo substr($at, 1); // example.com
}

For a case-insensitive substring match, see stristr(). Finding https:// or <a in input is not reliable link detection or input sanitization. Validate submitted URLs separately, escape text with htmlspecialchars() before HTML output, and allow HTML only through an appropriate sanitizer.

Searching Blank space inside a string

$string='first second';
if (strstr($string,' ')) {
echo " There is blank space present inside the string ";
}else{
echo " There is NO blank space present inside the string ";
}

The output is

 There is blank space present inside the string

String Functions stristr(): case-insensitive search

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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strstr():Searching for a match inside a string

Find the first matching substring with strstr()

Example of strstr()

When to use strstr()

Searching Blank space inside a string

Subhendu Mohapatra