Ruby Methods

So, you can define a simple method as follows:

You can define a method that accepts parameters as follows:

You can set default values for parameters, which will be used if the required parameters are not passed when the method is called:

When you want to call a method, you only need to use the method name, as follows:

However, when you call a method with parameters, you need to include the parameters when writing the method name, for example:

The biggest disadvantage of using methods with parameters is that you need to remember the number of parameters when calling the method. For example, if you pass only two arguments to a method that accepts three parameters, Ruby will show an error.

The output of the above example is:

编程语言为 C
编程语言为 C++
编程语言为 Ruby
编程语言为 Perl

Returning Values from Methods

Every method in Ruby returns a value by default. The returned value is the value of the last statement. For example:

When this method is called, the last declared variable k will be returned.

Ruby returnStatement

In Ruby, thereturnstatement is used to return one or more values from a Ruby method.

If more than two expressions are given, an array containing these values will be the return value. If no expression is given, nil will be the return value.

Look at the following example:

The output of the above example is:

100
200
300

Variable Number of Parameters

Suppose you declare a method with two parameters. When you call that method, you also need to pass two arguments.

However, Ruby allows you to declare methods with a variable number of parameters. Let's look at the following example:

In this code, you have declared a method sample that accepts a parameter test. However, this parameter is a variable parameter. This means that the parameter can take a variable number of variables. The output of the above example is:

参数个数为 3
参数值为 Zara
参数值为 6
参数值为 F
参数个数为 4
参数值为 Mac
参数值为 36
参数值为 M
参数值为 MCA

Class Methods

When a method is defined outside a class, it is marked as private by default.privateOn the other hand, if a method is defined inside a class, it is marked as public by default.

The default visibility andprivatemarker can be changed through the module (Module)'spublicorprivatepublic or private.

When you want to access a class's methods, you first need to instantiate the class. Then, using the object, you can access any member of the class.

Ruby provides a way to access methods without instantiating. Let's see how to declare and access class methods:

We already know how the method return_date is declared. It is declared by placing a dot after the class name, followed by the method name. You can directly access class methods, as follows:

To access this method, you do not need to create an object of the class Accounts.

Ruby aliasStatement

This statement is used to alias a method or a global variable. Aliases cannot be defined inside a method body. Even if the method is overridden, the alias of the method preserves the current definition of the method.

Aliasing numbered global variables ($1, $2,...) is forbidden. Overriding built-in global variables may cause serious problems.

Syntax

Here, we have defined the alias foo for bar, and the alias $MATCH for $&.

Ruby undefStatement

This statement is used to undefine a method.undefIt cannot appear inside a method body.

By usingundefandalias, the class's interface can be modified independently from the parent class, but please note that it may break the program when calling methods inside itself.

Example

The following example undefines the method namedbarmethod definition:

Other Extensions