用新行打印执行流程

Question

package main

import (
    "fmt"
    "math"
)

func pow(x, n, lim float64) float64 {
    if v := math.Pow(x, n); v < lim {
        return v
    } else {
        fmt.Printf("%g >= %g
", v, lim)
    }
    // can't use v here, though
    return lim
}

func main() {
    fmt.Println(
        pow(3, 2, 10),
        pow(3, 3, 20),
    )
}

this code is from "A Tour of GO"

Expectation:

9   
10   
27 >= 20     
20

Output:

27 >= 20    
9 20

I don't understand about this. help me!

Answer 1

Println function will output of both pow functions in a single line and then it adds after returning from Println function.

package main

import (
    "fmt"
    "math"
)

func pow(x, n, lim float64) float64 {
    if v := math.Pow(x, n); v < lim {
        return v
    }else {
        fmt.Printf("%g >= %g
", v, lim)
    }
    // can't use v here, though
    return lim
}

func main() {
    fmt.Println(pow(3, 2, 10))
    fmt.Println(pow(3, 3, 20))
}

Playground

And 10 which is the limit in first if case will never print.

9
10
27 >= 20
20

Because pow function is returned before in the function.