PHP is a server-side scripting language that is simple to learn. It enables developers to build logic into the development of web page content and handle the data returned from a web browser, just like any other scripting language. Str_replace in PHP also includes a variety of plugins that make it simple to communicate with databases. It also enables the extraction of data for display on a web page, and the storage of data entered by a website user back into the database.

PHP is made up of two parts: a scripting language and an interpreter. Str_replace in PHP, like other scripting languages, allows web developers to specify the actions and logic that a web page needs. 

The web server embeds these scripts in the HTML documents that are served. The interpreter is a module that integrates into the webserver and converts scripts into commands. The machine then executes them to achieve the results specified by the web developer in the document.

Stand Out From Your Peers this Appraisal Season

Start Learning With Our FREE CoursesEnroll Now
Stand Out From Your Peers this Appraisal Season

What Is str_replace in PHP?

In a string, the Str_replace in PHP function replaces certain characters with other characters.


The following are the rules governing the Str_replace in PHP:

  • It returns an array if the string to be searched is an array
  • If the string to be searched is an array, it applies the find and replace function to each portion of the array
  • It replaces an empty string if both find and replace are arrays and replace has fewer elements than find
  • If replace is a string and find is an array, it will use the replace string for each find value
  • This role is case-sensitive. To perform a case-insensitive search, use the Str_replace in PHP function.



// Input string

$str = "You eat fruits, vegetables, fiber every day.";

// Array containing search string

$searchVal = array("fruits", "vegetables", "fiber");

// Array containing replace string from search string

$replaceVal = array("pizza", "beer", "ice cream");

// Function to replace string

$res = str_replace($searchVal, $replaceVal, $str);





Here's How to Land a Top Software Developer Job

Full Stack Developer - MERN StackExplore Program
Here's How to Land a Top Software Developer Job

Definition and Usage 

Until Str_replace in PHP 4.3.3, this feature had a lot of issues when using both the $search and $replace parameters as an array. As a result, it used to skip empty $search indexes without the internal pointer on the $replace list being advanced. It has fixed this issue in newer versions. Most of the parameters in PHP 4.0.5 can now be an array.



$string = "Hii everyone!";  

$search = 'Hii';  

$replace = 'Hello';  

echo '<b>'."String before replacement:".'</br></b>';  

echo $string.'</br>';  

$newstr = str_replace($search, $replace, $string, $count);  

echo '<b>'."New replaced string is:".'</br></b>';  

echo $newstr.'</br>';  

echo 'Number of replacement ='.$count;  




Understanding Parameter Values Along With Their Use Case:

  • $searchVal: This parameter can take the form of a string or an array. This parameter defines the string to be checked and substituted 
  • $replaceVal: This parameter can take the form of a string or an array. This parameter defines the string with which you want to replace the $searchVal string 
  • $subjectVal: This parameter can take the form of a string or an array. It defines the string or sequence of strings for which $searchVal should be searched and $replaceVal should replace.
  • If passed, it will set the value of $count to the total number of replacement operations performed on the string $subjectVal.

If both the $searchVal and $replaceVal arguments are arrays, the $searchVal argument's elements are searched in the $subjectVal string and replaced by the $replaceVal argument's elements. If the number of elements in $replaceVal is less than the number of elements in the $searchVal sequence, an empty string replaces any additional elements of the $searchVal argument found in the $subjectVal argument. If the $subjectVal parameter is an array rather than a string, it will search all elements of $subjectVal.



// Input string

$subjectVal = "It was nice meeting you. May you shine bright.";

// using str_replace() function

$resStr = str_replace('you', 'him', $subjectVal);





Advance your career as a MEAN stack developer with the Full Stack Web Developer - MEAN Stack Master's Program. Enroll now!


When the parameters are arrays, it searches for all the find argument's elements in the string and replaces them with the corresponding elements in the replace argument. If the number of elements in the replace argument is less than the number of elements in the find sequence, any additional elements in the find argument that appear in the string argument are replaced by an empty string. If the string parameter is an array instead of a string, all of the Str_replace in PHP elements will be scanned. 

This function is case-sensitive, so you use str replace() to perform a case-insensitive match to solve the issue. Learn Str_replace in PHP from Simplilearn's Full Stack Web Deveopment course.  Improve your skills in the best manner with the right course to help you out.

Have any questions for us? Leave them in the comments section of this article. Our experts will get back to you on the same as soon as possible!