where is error log in wordpress code example

Example 1: wordpress write all error in log

//You can enable WordPress logging adding this to wp-config.php file
// Enable WP_DEBUG mode
define( 'WP_DEBUG', true );

// Enable Debug logging to the /wp-content/debug.log file
define( 'WP_DEBUG_LOG', true );

Example 2: error_log wordpress

error_log( 'Hello World!' );