Golang学习笔记_02——函数

Golang测试功能应用
Golang学习笔记_01——包

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函数

Go语言中的函数是一种基本的编程结构，用于封装一段代码，以便在需要时多次调用。函数可以接收参数并返回结果，是实现代码复用和模块化编程的重要手段。

1. 定义

在Go语言中，函数通过func关键字定义。一个基本的函数定义包括函数名、参数列表、返回类型（如果有的话）、以及函数体。

当连续两个或多个函数的已命名形参类型相同时，除最后一个类型以外，其它都可以省略。

package function_demo

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

add函数接收两个int类型的参数，并返回一个int类型的结果。

对刚刚定义的函数进行测试

package function_demo

import (
	"fmt"
	"testing"
)

func TestFunctionDemo(t *testing.T) {
	fmt.Println("sum = ", add(1, 2))
}

测试结果

=== RUN   TestFunctionDemo
sum =  3
--- PASS: TestFunctionDemo (0.00s)
PASS

2. 返回值

Go语言中的函数可以返回多个值。这在处理错误或其他需要返回多个结果的情况下非常有用。

func AddAndSubtract(a int, b int) (int, int) {
	sum := a + b
	diff := a - b
	return sum, diff
}

测试方法

func TestAddAndSubtract(t *testing.T) {

	sum, diff := AddAndSubtract(100, 99)
	fmt.Println("sum = ", sum, "\n", "diff = ", diff)

}

输出结果

=== RUN   TestFunctionDemo2
sum =  199 
diff =  1
--- PASS: TestFunctionDemo2 (0.00s)
PASS

3. 命名返回值

Go语言支持命名返回值，这可以让代码更加清晰和简洁。

命名返回值在函数定义时指定名称，并在函数体中直接使用这些名称，最后通过裸返回（即直接写return）来返回这些值。

func addAndSubtractNamed(a int, b int) (sum int, diff int) {
	sum = a + b
	diff = a - b
	return sum, diff
}

测试方法

func Test_addAndSubtractNamed(t *testing.T) {
	sum, diff := AddAndSubtract(1000, 99)
	fmt.Println("sum = ", sum, "\n", "diff = ", diff)
}

输出结果

=== RUN   Test_addAndSubtractNamed
sum =  1099 
 diff =  901
--- PASS: Test_addAndSubtractNamed (0.00s)
PASS

4. 可变参数

Go语言中的函数也支持可变参数（即接收不定数量的参数）。

通过将一个参数类型设置为...T（其中T是参数类型），可以定义一个可变参数列表。

func sumAll(nums ...int) int {
	sum := 0
	for _, num := range nums {
		sum += num
	}
	return sum
}

测试方法

func Test_sumAll(t *testing.T) {
	fmt.Println("sum all = ", sumAll(1, 2, 3, 100, -90))
}

输出结果

=== RUN   Test_sumAll
sum all =  16
--- PASS: Test_sumAll (0.00s)
PASS

---

源码

// function_demo.go
package function_demo

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

func AddAndSubtract(a int, b int) (int, int) {
	sum := a + b
	diff := a - b
	return sum, diff
}

func addAndSubtractNamed(a int, b int) (sum int, diff int) {
	sum = a + b
	diff = a - b
	return sum, diff
}

func sumAll(nums ...int) int {
	sum := 0
	for _, num := range nums {
		sum += num
	}
	return sum
}

// function_demo_test.go
package function_demo

import (
	"fmt"
	"testing"
)

func TestFunctionDemo(t *testing.T) {
	fmt.Println("sum = ", add(1, 2))
}

func TestAddAndSubtract(t *testing.T) {

	sum, diff := AddAndSubtract(100, 99)
	fmt.Println("sum = ", sum, "\n", "diff = ", diff)

}

func Test_addAndSubtractNamed(t *testing.T) {
	sum, diff := AddAndSubtract(1000, 99)
	fmt.Println("sum = ", sum, "\n", "diff = ", diff)
}

func Test_sumAll(t *testing.T) {
	fmt.Println("sum all = ", sumAll(1, 2, 3, 100, -90))
}