PHP函数:method_exists和function_exists
method_exists
检查类的方法是否存在
<span 1</span> bool <span method_exists</span> ( <span mixed</span> <span $object</span> , <span string</span> <span $method_name</span> )
检查类的方法是否存在于指定的object中
参数:
object:对象示例或类名
method_name:方法名
返回值:
如果method_name所指的方法在object所指的对象类中已定义,则返回TRUE,否则返回FALSE。
注释:
如果此类不是已知类,使用此函数会使用任何已注册的autoloader。
function_exists
若提供的方法已经定义,则返回TRUE。
<span 1</span> bool <span function_exists</span> ( <span string</span> <span $function_name</span> )
检查已定义的方法列表,包括内置的(PHP内部的)和用户定义的。
参数:
方法名,字符串类型。
返回值:
当方法名存在且为方法时,返回TRUE,否则返回FALSE。
note:
This function will return FALSE
for constructs, such as include_once and echo.

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