如何将字符串转换为运算符？

Question

Is there a way to convert a string (e.g. "+", "-", "/", "*") into their respective math operators (+, -, /, *)?

In Python you can do:

import operator
ops = {"+": operator.add, "-": operator.sub} # etc.
print ops["+"](1,1) # prints 2

Is there a similar library or method for Go?

Answer 1

You can do this with function values:

ops := map[string]func(int, int) int{
    "+": func(a, b int) int { return a + b },
    "-": func(a, b int) int { return a - b },
    "*": func(a, b int) int { return a * b },
    "/": func(a, b int) int { return a / b },
}

fmt.Println(ops["+"](4, 2))
fmt.Println(ops["-"](4, 2))
fmt.Println(ops["*"](4, 2))
fmt.Println(ops["/"](4, 2))

Output: Go Playground

6
2
8
2

For a nice print:

a, b := 4, 2
for op, fv := range ops {
    fmt.Printf("%d %s %d = %d
", a, op, b, fv(a, b))
}

Output:

4 / 2 = 2
4 + 2 = 6
4 - 2 = 2
4 * 2 = 8