golang函数

golang 函数

可变参数列表

//可变参数
func sum(numbers ...int) int {
	s := 0
	for i := range numbers {
		s += numbers[i]
	}
	return s
}

　　

package main

import (
	"fmt"
	"math"
	"reflect"
	"runtime"
)
//返回一个参数
func eval(a, b int, op string) (int, error) {
	switch op {
	case "+":
		return a + b, nil
	case "-":
		return a - b, nil
	case "*":
		return a * b, nil
	case "/":
		return a / b, nil
	default:
		//panic 主动输出错误,中断程序
		//panic("unsupported operation: " + op)
		return 0, fmt.Errorf("unsupported operation: %s", op)
	}
}
//返回多个参数
func dic(a, b int) (int, int) {
	return a / b, a % b
}
//函数式编程
func fcunApply(op  func(int, int) int, a, b int) int {
	p := reflect.ValueOf(op).Pointer()
	opName := runtime.FuncForPC(p).Name()
	fmt.Printf("Calling function %s with args " + "(%d, %d) \n", opName, a, b)
    return op(a, b)
}
//
func power(a, b int) int {
	return int(math.Pow(float64(a), float64(b)))
}


func main() {
	if result, err := eval(1, 2, "+"); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println(result)
	}
	fmt.Println(eval(1, 2, "+a"))
	a, b := dic(13, 4)
	fmt.Println(a, b)
	fmt.Println(fcunApply(power, 3, 4))
        //匿名函数
	fmt.Println(fcunApply(
		func(a int, b int) int {
			return int(math.Pow(
				float64(3), float64(4)))
			}, 3, 4))
}