includevsincludeonce

Include() vs Include_once() In PHP – Difference

Pratik Patel PHP

Today we are going to learn the most basic thing in PHP which will be very helpful to beginners while exploring the PHP Language’s basic concepts. This concept is very small, however, you have to understand it properly if you want to be a good developer in PHP. So now let see what is the actual use of include() and include_once().

Syntax :

include('filename');
 
or
 
include_once('filename');

Functional Work :

Both functions have similar work. Both functions will include and evaluates the specific file while executing the code.

Functional Difference :

There is only one difference between these two functions. If the code a from a file has been already included then it will not be included again if we use include_once(). Means include_once() include the file only once at a time.

Let’s see one example for the same so we will get a better idea on this.

Assume that we have three files.

  • Helper.php
  • General.php
  • Index.php

These three files  have a code like below :

Helper.php

<?php 
Function displayMessage()
{
	echo  "This is Helper File";
}
?>

General.php

<?php 
include("Helper.php");
?>

Index.php

<?php 
include("General.php");
include("Helper.php"); 
?>

Now execute the Index.php file. You will get this error as a result.

Include

Fatal Error :

Cannot redeclare displayMessage() function. It’s already declared in Helper.php file. It will break the execution of your code because here we are getting a fatal error as a result. This is going to be happening because we have included the Helper.php file twice. So It will try to create the function two times with the same name. As per the PHP Coding standards, it will not allow you to create the same name function two times.

So If you  want to avoid such problems while programming then you must know the actual use of each function. Now we will see how to tackle such problems.

Now Please write the below code in Index.php file.

<?php 
include("General.php"); 
include_once("Helper.php");
displayMessage();
echo "<br/>This is Index File";
?>

Now Execute the Index.php file. You will not get any error. You will get an output like below.

Output :

This is Helper File

This is Index File

Benefit of using include() in place of require() :

These two perform the same function, however, the major difference is require() will throw a fatal error (E_COMPILE_ERROR )  since it is not able to find the specific file on specified location and it will break the execution as a result, while include() will show the warning (E_WARNING), however it will not break the script execution. To understand this in detail Click here…

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  13. I am getting this error
    Notice: Use of undefined constant product_id – assumed ‘product_id’ in /Applications/XAMPP/xamppfiles/htdocs/fashion/public/importcsv.php on line 49

    Modified following code:

    if (move_uploaded_file($_FILES[“fileToUpload”][“tmp_name”], $target_file)) {
    $message .=”File uplaoded successfully.”;

    if (($getdata = fopen($target_file, “r”)) !== FALSE) {
    fgetcsv($getdata);
    while (($data = fgetcsv($getdata)) !== FALSE) {
    $fieldCount = count($data);
    for ($c=0; $c < $fieldCount; $c++) {
    $columnData[$c] = $data[$c];
    }
    $prod_serial_no = mysqli_real_escape_string($con ,$columnData[0]);
    $product_id = mysqli_real_escape_string($con ,$columnData[1]);
    $product_name = mysqli_real_escape_string($con ,$columnData[2]);
    $description = mysqli_real_escape_string($con ,$columnData[3]);
    $img_url = mysqli_real_escape_string($con ,$columnData[4]);
    $price = mysqli_real_escape_string($con ,$columnData[5]);
    $product_url = mysqli_real_escape_string($con ,$columnData[6]);
    $aff_company = mysqli_real_escape_string($con ,$columnData[7]);
    $brand = mysqli_real_escape_string($con ,$columnData[8]);
    $stock = mysqli_real_escape_string($con ,$columnData[9]);
    $size = mysqli_real_escape_string($con ,$columnData[10]);
    $size_value = mysqli_real_escape_string($con ,$columnData[11]);
    $color = mysqli_real_escape_string($con ,$columnData[12]);
    $color_value = mysqli_real_escape_string($con ,$columnData[13]);
    $main_cat = mysqli_real_escape_string($con ,$columnData[14]);
    $sub_main_cat = mysqli_real_escape_string($con ,$columnData[15]);
    $sub_cat = mysqli_real_escape_string($con ,$columnData[16]);
    $import_data[]="('".$prod_serial_no."','".product_id."','".$product_name."','".$description."','".$img_url."','".$price."','".$product_url."','".$aff_company."','".$brand."','".$stock."','".$size."','".$size_value."','".$color."','".$color_value."','".$main_cat."','".$sub_main_cat."','".$sub_cat."')";

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