PHP - URL base64_decode() Function

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The PHP URL base64_decode() function is used to decode data encoded with the base64 algorithm. This function accepts two parameters and returns the decoded data as a string.

Syntax

Below is the syntax of the PHP URL base64_decode() function −

string base64_decode( string $data [, bool $strict = false ] )

Parameters

Below are the parameters of the base64_decode() function −

• $data − It is the Base64 encoded string that you want to decode.

• $strict − The function will return false if it is set to true and the input contains characters that are not part of the base64 alphabet. The default value is false.

Return Value

The base64_decode() function returns the decoded data as a string and false if the input is invalid and $strict is set to true.

PHP Version

First introduced in core PHP 4, the base64_decode() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

Here is the basic example of the PHP URL base64_decode() function to decode the given encoded string.

<?php
   // Define encoded string here
   $str = "SGVsbG8gVHV0b3JpYWxzcG9pbnQh";

   // Decode the string using base64_decode() function
   $decodedString = base64_decode($str);

   // Print the decoded message
   echo $decodedString;
?>

Output

The above code will result something like this −

Hello Tutorialspoint!

Example 2

In the below PHP code we will try to use the base64_decode() function and also provide the strict parameter here.

<?php
   // Define encoded string here
   $str = "SGVsbG8gV29ybGQh";
   $decodedString = base64_decode($str, true);
   if ($decodedString === false) {
       echo "Invalid Base64 string.";
   } else {
       echo $decodedString; 
   }
?> 

Output

This will generate the below output −

Hello World!

Example 3

Now in the below code we will decode a Base64 encoded JSON string with the help of base64_decode() function.

<?php
   // Define the encoded json here
   $str = "eyJrZXkiOiAidmFsdWUifQ==";
   $decodedJson = base64_decode($str);
   $jsonArray = json_decode($decodedJson, true);
   print_r($jsonArray); 
?> 

Output

This will create the below output −

Array ( [key] => value )

Example 4

Using the base64_decode() function now we will decode an image file and save it in the given path with the name provided.

<?php
   // Define encoded string of an image
   $imgstr = "iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4
   //8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";
   
   // Use base64_decode() function here
   $decodedImg = base64_decode($imgstr);

   // Save the image file
   file_put_contents("/PhpProjects/decoded_image.png", $decodedImg); 

   echo "The decoded image has been saved in the directory!";
?> 

Output

Following is the output of the above code −

The decoded image has been saved in the directory!