Go语言生成随机运算符并计算表达式

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {
    rand.Seed(time.Now().UnixNano()) // 使用当前时间作为种子，确保每次运行生成不同的随机数
    operators := "+-/*"
    op := operators[rand.Intn(len(operators))]
    fmt.Printf("%c\n", op)
}

package main

import (
    "fmt"
    "strconv"
    "strings"
)

func check(err error) {
    if err != nil {
        panic(err)
    }
}

func main() {
    expr := strings.Fields("4 * 8 / 2 * 3")
    fmt.Printf("%#v\n", expr)

    do := func(i int, op func(a, b int) int) {
        ai, err := strconv.Atoi(expr[i-1])
        check(err)
        bi, err := strconv.Atoi(expr[i+1])
        check(err)
        expr[i-1] = strconv.Itoa(op(ai, bi))
        expr = append(expr[:i], expr[i+2:]...)
        fmt.Printf("%#v\n", expr)
    }

    for _, ops := range []string{"*/", "+-"} {
        for i := 0; i < len(expr); i++ {
            if strings.Contains(ops, expr[i]) {
                switch expr[i] {
                case "*":
                    do(i, func(a, b int) int { return a * b })
                case "/":
                    do(i, func(a, b int) int { return a / b })
                case "+":
                    do(i, func(a, b int) int { return a + b })
                case "-":
                    do(i, func(a, b int) int { return a - b })
                }
                i -= 2
            }
        }
    }

    fmt.Println(expr[0])
}