Remove warning messages in PHP

You can put an @ in front of your function call to suppress all error messages.

@yourFunctionHere();

To suppress warnings while leaving all other error reporting enabled:

error_reporting(E_ALL ^ E_WARNING);

If you don't want to show warnings as well as errors use

// Turn off all error reporting
error_reporting(0);

Error Reporting - PHP Manual

If you want to suppress the warnings and some other error types (for example, notices) while displaying all other errors, you can do:

error_reporting(E_ALL & ~E_WARNING & ~E_NOTICE);

in Core Php to hide warning message set error_reporting(0) at top of common include file or individual file.

In Wordpress hide Warnings and Notices add following code in wp-config.php file

ini_set('log_errors','On');
ini_set('display_errors','Off');
ini_set('error_reporting', E_ALL );
define('WP_DEBUG', false);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);

I do it as follows in my php.ini:

error_reporting = E_ALL & ~E_WARNING  & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED

This logs only fatal errors and no warnings.

Not exactly answering the question, but I think this is a better compromise in some situations:

I had a warning message as a result of a printf() statement in a third-party library. I knew exactly what the cause was - a temporary work-around while the third-party fixed their code. I agree that warnings should not be suppressed, but I could not demonstrate my work to a client with the warning message popping up on screen. My solution:

printf('<div style="display:none">');
    ...Third-party stuff here...
printf('</div>');

Warning was still in page source as a reminder to me, but invisible to the client.

You could suppress the warning using error_reporting but the much better way is to fix your script in the first place.

I think that better solution is configuration of .htaccess In that way you dont have to alter code of application. Here are directives for Apache2

php_flag display_startup_errors off
php_flag display_errors off
php_flag html_errors off
php_value docref_root 0
php_value docref_ext 0

There is already answer with Error Control Operator but it lacks of explanation. You can use @ operator with every expression and it hides errors (except of Fatal Errors).

@$test['test']; //PHP Notice:  Undefined variable: test

@(14/0); // PHP Warning:  Division by zero

//This is not working. You can't hide Fatal Errors this way.
@customFuntion(); // PHP Fatal error:  Uncaught Error: Call to undefined function customFuntion()

For debugging it's fast and perfect method. But you should never ever use it on production nor permanent include in your local version. It will give you a lot of unnecessary irritation.

You should consider instead:

1. Error reporting settings as mentioned in accepted answer.

error_reporting(E_ERROR | E_PARSE);

or from PHP INI settings

ini_set('display_errors','Off');

2. Catching exceptions

try {
    $var->method();
} catch (Error $e) {
    // Handle error
    echo $e->getMessage();
}