如何让 PHP 显示错误

### Answer: Use the ini_set() Function
For security reasons, error display in production environments is disabled by default.

But, if you want to display errors in a PHP file for debugging purposes, you can place these lines of code at the top of your PHP file, as shown in the following example:

```php
<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
ini_set('error_reporting', -1);

// Rest of code here...
?>
```
However, this doesn't make PHP to show parse errors (such as missing semicolon). The only way to show those errors is to set the `display_errors` directive to `On` in `php.ini` file. By default `display_errors` set to `Off` for production environments.

```
display_errors = On
```

After modifying the php.ini file restart your web server, or php-fpm service if you are using PHP-FPM.

However, if you don't have access to `php.ini` file—for instance, if you're using a shared hosting—then putting the following line in `.htaccess` file might also work.

```
php_flag display_errors 1
```
<div class="callout callout-warning mb-3">Warning: Outputting errors in production environments could be very dangerous. Sensitive information could potentially leak out of your application such as database usernames and passwords or worse. For production environments, logging errors is recommended.</div>