Function declaration
In the Go language, common function declaration syntax is as follows:
functionName FUNC (parameterName type) returnType {
// function body (specific functions implemented)
}
Function declaration keyword to func start, followed by the name of a custom function functionname (函数名). In the parameter list defined functions ( and ) between, the return type of the following defines returntype (返回值类型)at. The syntax for declaring a parameter using the parameter name parameter type of way, any number of similar parameters (parameter1 type, parameter2 type) 即(参数1 参数1的类型,参数2 参数2的类型)specified in the form. After contained in { and } code between, it is the function thereof.
The list of parameters and return values of the function is not required, so the following function declarations are also effective
functionName FUNC () {
// Annotation: This function does not need to represent the input parameters and returns no value
}
The sample program
main Package
Import "FMT"
// single parameter passed
FUNC functionname1 (parameterName int) {
fmt.Printf ( "Parameters:% D \ n-", parameterName);
}
// pass a single parameter, a single return value
func functionname2 (parametername int) {int
fmt.Printf ( "parameters:% D \ n-", parameterName);
return parameterName * parameterName;
}
// pass the plurality of parameters
FUNC functionname3 (parametername1 int, int parametername2) {
fmt.Printf ( "parameter 1 :% D \ n-", parametername1);
fmt.Printf (" parameter 2:% D \ n-", parametername2);
}
// pass a plurality of parameters, a plurality of return value
func functionname4 (parametername1 int, parametername2 int ) ( int, int) {
fmt.Printf ( "parameters. 1: D% \ n-", parametername1);
fmt.Printf ( "parameter 2:% d \ n", parametername2);
return parametername1 * parametername2,parametername1 + parametername2;
}
func main(){
a := 1;
b := 2;
functionname1(a);
functionname2(a);
functionname3(a,b);
functionname4(a,b);
}
Named return value
It may return a value from the function name. Once named return values, these values can be considered the first line of the function is declared as variables.
RectProps above function may also be written in this way:
rectProps FUNC (length, width float64) (Area, perimeter float64) {
Area = length * width
perimeter = (length + width) * 2
return // do not need to explicitly specify the return value returned by default Area, the value of the perimeter
}
Please note that the return statement in the function does not explicitly return a value. Since the area and perimeter specified in the function declaration to return a value, so when faced with a return statement, they will automatically return from the function.
Whitespace
_ Is used as a blank character in Go, any value can be used to represent any type.
We continue to rectProps function as an example, the function calculates the area and perimeter of is. If we only need to calculate the area, perimeter and do not care about the results, how to call this function? At this time, whitespace _ to turn.
The following program we only used the function rectProps a return value area
package main
import (
"fmt"
)
func rectProps(length, width float64) (float64, float64) {
var area = length * width
var perimeter = (length + width) * 2
return area, perimeter
}
func main() {
area, _ := rectProps(10.8, 5.6) // 返回值周长被丢弃
fmt.Printf("Area %f ", area)
}
Run the program
In the program of
area, _ := rectProps(10.8, 5.6)this line, we see white space_used to skip unwanted results.
refer：