有没有办法显示或抛出 PHP 警告？
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Is there any way to show, or throw, a PHP warning?
提问by igorsantos07
I have a select()method in a database class, that has an optional boolean argument $sum. This argument is used to say if the method should use COUNT(*)or not too.
我select()在数据库类中有一个方法，它有一个可选的布尔参数$sum。此参数用于说明该方法是否也应使用COUNT(*)。
I would like to show a warning, like those normal PHP errors, if I try to access $class->sumif the attribute is not set (i.e. when I call select()with $sum == false.
我想显示一个警告，像普通的PHP错误，如果我尝试访问$class->sum如果属性未设置（即当我打电话select()用$sum == false。
Is there any way to show a warning like this, or I should just echo an error and be happy?
有没有办法显示这样的警告，或者我应该只回显错误并感到高兴？
回答by T30
If you want to generate a warning, you should write
如果你想产生一个警告，你应该写
trigger_error($yourErrorMessage, E_USER_WARNING);
trigger_error()has the $error_typeparameter for setting the error level (Notice, Warningor Fatal error). The constants are, respectively:
trigger_error()具有$error_type用于设置错误级别的参数（Notice、Warning或Fatal error）。常数分别为：
E_USER_NOTICE // Notice (default)
E_USER_WARNING // Warning
E_USER_ERROR // Fatal Error
Note that Fatal errorstops the execution of subsequent PHP code, while Noticeand Warninglet it continue.
请注意，Fatal error停止后续PHP代码的执行，而Notice并Warning让它继续。
From PHP 5.5, you should also consider the Finallystatement.
从 PHP 5.5 开始，您还应该考虑finally语句。
回答by alex
You could try trigger_error().
你可以试试trigger_error()。
回答by moo
You're going the object-oriented approach, so I suggest a look into exceptions.
您将采用面向对象的方法，因此我建议您查看异常情况。
