PHP String strstr() function

The strstr() function is an in-built function of PHP. It is a case-sensitive function which finds the first occurrence of a string. The strstr() is mainly used to search the first occurrence of a string inside another string and displays some part of the latter starting from the first occurrence of the former in latter.

It is a binary-safe function, means a function that can perform on binary files without modifying the content of the file. The strstr() function is similar to stristr() function, but the only difference is that - stristr() is case-insensitive function whereas strstr() is case-sensitive.

Note: The strstr() is binary-safe and case-sensitive function.

Syntax

The syntax for the PHP strstr() function is given below, which consists three parameters.

Parameters

$string (required): $string is a mandatory parameter which specifies the string to be searched. In other words, it is the main string parameter in which $search value is searched.

$search (required): The next mandatory parameter of this function is $search. It specifies that string which is going to be searched in $string parameter. If this parameter contains a number or integer value rather than a string, then it will search for character matching ASCII value for that number.

$before_search (optional): It is the last and optional parameter of strstr() function which specifies the Boolean value, whose default value is FALSE. If we set it to TRUE, then it will return the part of the string before the first occurrence of the search parameter.

Return Values

The PHP strstr() returns the remaining string (from the matching point), or it will return FALSE if the string which we are searching for is not found.

Technical Details

Examples of strstr()

There are some examples given below that will help us to learn the practical use of this function.

//Returns remaining string after search found
Input:
$string1 = "Hello! Good Morning everyone", $search1 = "Good";
Output: Morning everyone

//case-sensitive, returns nothing
Input:
$string = "Hello! Good Morning everyone ", $search = "HELLO ";
Output: 							

//Returns initial string when search found
Input:
$string = "Hello! Good Morning everyone", $search = "Good", before_search = true;
Output: Hello!								

//Passing ASCII value of r which is 114
Input:
$string = "I want to travel the world ", $search = "114", before_search = true;
Output: I want to t

Below some detailed examples are given. With the help of these examples, we can understand the use of this function in a much better way.

Example 1

It is a simple example of strstr() which shows that it is a case-sensitive function, so it returns FALSE if the string does not match. It will return the rest of the string from where the $search variable will find in the string.

Output:

Example 2

In this below example, we will use a third parameter $before_search, whose default value is FALSE. Here, we will set it to TRUE, which will return the part of the string before the first occurrence of the $search parameter. If the search string is not found, then it will return the Boolean value false.

Output:

Example 3

We can also pass an integer value in $search parameter rather than the string or character. This integer value is treated as ASCII value and converted into character. In this example, we will pass an integer in $search.

Output:

Note: var_dump() function is mainly used to display the Boolean values on the browser. Other than the Boolean value, it displays the datatype of parameter and number of character available in that parameter, as you can see in the above example. Echo is not sufficient to print these information.