在Go中如何将float64转换为int？

问题描述：

如何在Go中将浮点数64转换为int？我知道strconv包可以用于将任何内容转换成字符串或从字符串中转换，但不能在不是字符串的数据类型之间进行转换。我知道我可以使用fmt.Sprintf将任何内容转换为字符串，然后将其转换为我需要的数据类型，但是这种额外的转换似乎有点笨拙——有更好的方法吗？

如何在Go中将float64转换为int？我知道strconv code>包可用于在字符串之间进行任何转换，但不能用于不是字符串的数据类型之间的转换。我知道我可以使用 fmt.Sprintf code>将任何内容转换为字符串，然后将 strconv code>转换为所需的数据类型，但是这种额外的转换似乎有点笨拙-是还有更好的方法吗？ p> div>

答

package main
import "fmt"
func main() {
  var x float64 = 5.7
  var y int = int(x)
  fmt.Println(y)  // outputs "5"
}

答

Simply casting to an int truncates the float, which if your system internally represent 2.0 as 1.9999999999, you will not get what you expect. The various printf conversions deal with this and properly round the number when converting. So to get a more accurate value, the conversion is even more complicated than you might first expect:

package main

import (
    "fmt"
    "strconv"
)

func main() {
    floats := []float64{1.9999, 2.0001, 2.0}
    for _, f := range floats {
        t := int(f)
        s := fmt.Sprintf("%.0f", f)
        if i, err := strconv.Atoi(s); err == nil {
            fmt.Println(f, t, i)
        } else {
            fmt.Println(f, t, err)
        }
    }
}

Code on Go Playground

答

If its simply from float64 to int, this should work

package main

import (
    "fmt"
)

func main() {
    nf := []float64{-1.9999, -2.0001, -2.0, 0, 1.9999, 2.0001, 2.0}

    //round
    fmt.Printf("Round : ")
    for _, f := range nf {
        fmt.Printf("%d ", round(f))
    }
    fmt.Printf("
")

    //rounddown ie. math.floor
    fmt.Printf("RoundD: ")
    for _, f := range nf {
        fmt.Printf("%d ", roundD(f))
    }
    fmt.Printf("
")

    //roundup ie. math.ceil
    fmt.Printf("RoundU: ")
    for _, f := range nf {
        fmt.Printf("%d ", roundU(f)) 
    }
    fmt.Printf("
")

}

func roundU(val float64) int {
    if val > 0 { return int(val+1.0) }
    return int(val)
}

func roundD(val float64) int {
    if val < 0 { return int(val-1.0) }
    return int(val)
}

func round(val float64) int {
    if val < 0 { return int(val-0.5) }
    return int(val+0.5)
}

Outputs:

Round : -2 -2 -2 0 2 2 2 
RoundD: -2 -3 -3 0 1 2 2 
RoundU: -1 -2 -2 0 2 3 3

Here's the code in the playground - https://play.golang.org/p/HmFfM6Grqh

答

you can use int() function to convert float64 type data to an integer. Similarly you can use float64()

Eg:

func check(n int) bool { 
    // count the number of digits 
    var l int = countDigit(n)
    var dup int = n 
    var sum int = 0 

    // calculates the sum of digits 
    // raised to power 
    for dup > 0 { 
        **sum += int(math.Pow(float64(dup % 10), float64(l)))** 
        dup /= 10 
    } 

    return n == sum
}

在Go中如何将float64转换为int？

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