The definition and calling method of Golang function

Golang is a very popular programming language. Due to its efficiency, simplicity, and ease of use, more and more developers are beginning to use Golang to develop programs. In Golang, functions are a very important program structure, and this article will introduce you to the definition and calling methods of Golang functions.

1. Golang function definition

In Golang, the definition of a function consists of the following parts:

1. Function name

2. Parameter list

3. Return value list

4. Function body

We will introduce these four parts in detail below.

1. Function name

The function name is the identifier of the function, which is used to specify the function to be called when the function is called. The function name must meet the requirements for identifiers, that is, it must be composed of letters, numbers, underscores and other characters, and start with a letter or underscore.

2. Parameter list

The parameter list specifies the parameters that need to be passed when the function is called. A parameter list consists of a set of parameters, each consisting of a parameter name and a parameter type. Separate multiple parameters with commas.

In Golang, parameters have the following types:

a. Basic types: including Boolean, integer, floating point, complex, string, etc.

b. Structure type: a composite type composed of multiple variables.

c. Array type: An ordered collection composed of multiple elements of the same type.

d. Slice type: a variable-capacity sequence dynamically generated from an array.

e. Dictionary type: an unordered collection composed of key-value pairs.

f. Pointer type: points to the memory address of another variable.

g. Function type: The type of function as a parameter or return value.

3. Return value list

The return value list specifies the value returned by the function. The return value list consists of a set of parameters, each consisting of parameter types. Separate multiple parameters with commas.

In Golang, the return value has the following types:

a.Basic type

b.Structure type

c.Pointer type

d. Function type

4. Function body

The function body is the code block actually executed by the function and can contain any number of statements and expressions. The function body must be enclosed in a pair of curly braces, and each statement in the function body must end with a semicolon.

2. Golang function call

Function call refers to calling a defined function in the program. The syntax format of function call is:

Function name (parameter list)

where the function name is the name of the function to be called, and the parameter list is the parameters passed to the function.

Next, we will use some examples to illustrate how to call Golang functions.

1. Call a function without parameters

The following is a simple example showing how to call a function without parameters.

func hello() {
fmt.Println("Hello, world!")
}

func main() {
hello()
}

In this example, we define a function hello() without parameters and then call it in the main function.

2. Call a function with one parameter

The following is an example that demonstrates how to call a function with one parameter.

func add(a int, b int) int {
return a b
}

func main() {
sum := add(3, 4)
fmt.Println(sum)
}

In this example, we define a function add() with two integer parameters a and b, and then call it in the main function , and assign the return value to the sum variable.

3. Call a function with multiple return values

The following is an example that demonstrates how to call a function with multiple return values.

func swap(a, b string) (string, string) {
return b, a
}

func main() {
x, y := swap ("hello", "world")
fmt.Println(x, y)
}

In this example, we define a function swap(), and this function returns two string type return values. In the main function, we call the swap() function and assign its return value to x and y.

4. Call a function with indefinite parameters

The following is an example that demonstrates how to call a function with indefinite parameters.

func sum(numbers ...int) int {
total := 0
for _, num := range numbers {

  total += num

}
return total
}

func main() {
fmt.Println(sum(1, 2)) //Output 3
fmt.Println(sum(1, 2, 3, 4)) //Output 10
}

In this example, we define a function sum() that can accept any number of integer parameters, and then call it in the main function, passing a different number of Integer parameter.

3. Summary

This article introduces the definition and calling method of Golang functions. Functions are a very important program structure in Golang. Functions can help us decompose complex programs into small, manageable Reusable modules improve program readability and maintainability. Whether you are a beginner or an experienced developer, mastering the definition and calling methods of Golang functions is very important for writing efficient and high-quality programs.

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