How to use -> operator to call method in php

With the development of the Internet, the demand for Web applications is increasing, and PHP has become one of the main languages ​​​​for Web applications. When using PHP to develop web applications, we often need to use objects to organize and manage various types of data and functions. In PHP, objects can access attributes and call methods, and when calling methods, we use the -> operator.

In PHP, the syntax of method definition is as follows:

[访问修饰符] function 方法名([参数列表]){
    //方法体
}

When calling a method, we need to create the object first, and this is usually achieved through the new operator, as shown below:

$obj = new ClassName();

Among them, ClassName is the defined class name. Once the object is created successfully, we can use the -> operator to call the object method, as shown below:

$obj->methodName();

where methodName is the name of the method we need to call.

It should be noted that in PHP, the -> operator has high priority, so when we need to call multiple methods at the same time, we need to use brackets () to determine the order of execution, as follows Shown:

$obj->method1()->method2();

In the above example, we used parentheses to ensure that method1 is executed first, and then method2.

In addition to using the -> operator to call object methods, we can also use the call_user_func or call_user_func_array function to call object methods. These two functions are mainly used to dynamically call a given method, including private methods and protected methods.

Among them, the syntax of the call_user_func function is as follows:

call_user_func(callback, [参数1，参数2，……]);

And the syntax of the call_user_func_array function is as follows:

call_user_func_array(callback, [参数数组]);

The parameter callback can be one of the following three types:

• When calling the method directly, the callback parameter is an array, and the corresponding format is [array (object, method name), parameter 1, parameter 2, ...].
• If the static method of the object is called, the callback parameter is in string format, and the corresponding format is [ClassName::methodName, parameter 1, parameter 2, ...].
• If the method name is stored in a variable, the callback parameter is an array, and the corresponding format is [$object, $methodName, parameter 1, parameter 2, ...].

It should be noted that before PHP 5.4 version, we must use the call_user_func or call_user_func_array function to call protected methods and private methods, but after PHP 5.4 version, we can directly use the object name to Call protected methods and private methods as follows:

$obj->_protectedMethod(); //调用受保护方法
$obj->__privateMethod(); //调用私有方法

It should be noted that this calling method will cause errors in strict mode, so we need to use the @ symbol when initializing the object to prohibit errors. Throws:

$obj = @new ClassName();

In application development, we often need to use class libraries and frameworks, and these class libraries and frameworks usually contain many defined classes and methods. Therefore, when we need to call these methods, we need to first understand the parameters and return values ​​of these methods. When calling methods, we also need to pay attention to the access level and exception handling of the method to ensure the stability and reliability of the application.

In short, calling object methods in PHP is an important part of developing Web applications. On the basis of mastering the -> operator, we also need to understand the methods of dynamically calling methods such as call_user_func and call_user_func_array functions. At the same time, in application development, we also need to pay attention to the parameters, return values, access levels and exception handling of methods to ensure the stability and reliability of the application.

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