Golang学习笔记_02——函数
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))
}
原文地址：https://blog.csdn.net/LuckyLay/article/details/144371981
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