What is output buffering?

Question

What is output buffering and why is one using it in PHP?

Answer 1

Output buffering is used by PHP to improve performance and to perform a few tricks.

• You can have PHP store all output into a buffer and output all of it at once improving network performance.

• You can access the buffer content without sending it back to browser in certain situations.

Consider this example:

<?php
    ob_start( );
    phpinfo( );
    $output = ob_get_clean( );
?>

The above example captures the output into a variable instead of sending it to the browser. output_buffering is turned off by default.

• You can use output buffering in situations when you want to modify headers after sending content.

Consider this example:

<?php
    ob_start( );
    echo "Hello World";
    if ( $some_error )
    {
        header( "Location: error.php" );
        exit( 0 );
    }
?>