浮点数在Golang中返回零

Question

Why does this code always return zero:

package main

import "fmt"

func main() {
    var index_of_array int
    fmt.Scan(&index_of_array)
    var arr = make([]int, index_of_array)
    for i := 0; i < len(arr); i++ {
        fmt.Scan(&arr[i])
    }

    positive := 0
    negative := 0
    zero_ := 0
    for _, arr_v := range arr {
        if arr_v > 0 {
            positive++
        } else if arr_v < 0 {
            negative++
        } else if arr_v == 0 {
            zero_++
        }
    }

    fmt.Printf("%f ", float32(positive/len(arr)))
    fmt.Printf("%f ", float32(negative/len(arr)))
    fmt.Printf("%f ", float32(zero_/len(arr)))

}

i mean to output

A decimal representing of the fraction of positive numbers in the array. A decimal representing of the fraction of negative numbers in the array. A decimal representing of the fraction of zeroes in the array.

Sample Input

6

-4 3 -9 0 4 1

Sample Output

0.500000

0.333333

0.166667

but in my code the output like this with the same input

0.000000

0.000000

0.000000

Answer 1

I've done some modifications to your code and it should run as you expected:

package main

import (
    "fmt"
    "bufio"
    "os"
    "strconv"
)

func main() {
    scanner := bufio.NewScanner(os.Stdin)
    fmt.Print("Enter the lenght of the array: ")
    scanner.Scan()
    index_of_array, err := strconv.Atoi(scanner.Text())
    if err != nil {
        panic("Errroor!")
    }

    arr := make([]int, index_of_array)

    for i := 0; i < len(arr); i++ {
        fmt.Printf("Enter value number %d: ", i+1)
        scanner.Scan()
        arr[i], err = strconv.Atoi(scanner.Text())
        if err != nil {
            panic("Error 2!")
        }
    }

    positive := 0
    negative := 0
    zero_ := 0
    for _, arr_v := range arr {
        if arr_v > 0 {
            positive++
        } else if arr_v < 0 {
            negative++
        } else if arr_v == 0 {
            zero_++
        }
    }

    fmt.Println("Array entered: ", arr)
    fmt.Printf("There are %d positive number(s) of %d in the array. Fraction: %.6f
", positive, len(arr), float64(positive)/float64(len(arr)))
    fmt.Printf("There are %d negative number(s) of %d in the array. Fraction: %.6f
", negative, len(arr), float64(negative)/float64(len(arr)))
    fmt.Printf("There are %d zero(s) of %d in the array. Fraction: %.6f
", zero_, len(arr), float64(zero_)/ float64(len(arr)))

}

you can run it on repl.it

And you can use it like this example:

Enter the lenght of the array: 6
Enter value number 1: -4
Enter value number 2: 3
Enter value number 3: -9
Enter value number 4: 0
Enter value number 5: 4
Enter value number 6: 1
Array entered:  [-4 3 -9 0 4 1]
There are 3 positive number(s) of 6 in the array. Fraction: 0.500000
There are 2 negative number(s) of 6 in the array. Fraction: 0.333333
There are 1 zero(s) of 6 in the array. Fraction: 0.166667