Dark Horse Programmer--java Basic Syntax (c) function

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Function

1. Definition: In Java, a function is also called a method, which is a separate applet with a specific function.

2. Format: Modifier returns value type function name (parameter type form parameter 1, parameter type parameter 2)

{

Execute the statement;

return value;

}

Return value type: The data type of the result after the function is run.

Parameter type: The data type of the formal parameter.

Formal parameter: is a variable that stores the actual arguments passed to the function when the function is called.

Actual parameter: The specific value passed to the formal parameter.

return: Used to end the function.

Return value: The value is returned to the caller.

3. Features of functions

A, define functions to encapsulate the function code

b, facilitates the reuse of this function

C, the function will be executed only if it is called

D, the appearance of functions improves the reusability of code

E, for a function that does not have a specific return knowing the condition, the return value type is denoted by the keyword void, then the return statement in the function can be omitted from the last line if not written.

Note: A, only functions can be called in a function and cannot be defined inside a function.

b, define the function, and the result of the function should be returned to the caller, which is handled by the caller.

4. Application of Functions

How do I define a function?

A, since the function of a separate function, then the function of the results of the operation is to be clear first. (return value type for explicit functionality)

b, and then specify whether unknown content ( variables ) should be involved in the process of defining the function. (Specify the parameter list of the function (type and number of parameters))

5. An important feature of the function--overloading (override)

Concept: In the same class, more than one function with the same name is allowed, as long as the number of argument lists or the parameter types are different.

Features: Regardless of the return value type, see only the parameter list.

Benefits: Easy to read and optimized for programming.

Example:

Returns the number of two integers and

int add (int x,int y) {return x+y;}

Returns the number of three integers and

int add (int x,int y,int z) {returnx+y+z;}

Returns two decimals and

Double Add (double x,double y) {return x+y;}

When do I use the overload?

When the functions defined are the same, but the unknown contents of the participating operations are different. Then, a function name is defined to represent the function, to facilitate reading, and to distinguish multiple functions with the same name by different parameter lists.

Practice:

Dark Horse Programmer--java Basic Syntax (c) function