在Golang中将int32转换为字符串 [英] Convert int32 to string in Golang

问题描述

我需要在Golang中将int32转换为string.是否可以在Golang中将int32转换为string而不先转换为int或int64?

I need to convert an int32 to string in Golang. Is it possible to convert int32 to string in Golang without converting to int or int64 first?

Itoa需要一个int. FormatInt需要一个int64.

Itoa needs an int. FormatInt needs an int64.

推荐答案

一个答案是fmt.Sprint(i).

无论如何，甚至在诸如fmt.Sprint(i)之类的标准库函数内部，都有很多转换，因此您有一些选择(尝试 The Go游乐场):

Anyway there are many conversions, even inside standard library function like fmt.Sprint(i), so you have some options (try The Go Playground):

1-您可以编写转换函数(最快):

1- You may write your conversion function (Fastest):

func String(n int32) string {
    buf := [11]byte{}
    pos := len(buf)
    i := int64(n)
    signed := i < 0
    if signed {
        i = -i
    }
    for {
        pos--
        buf[pos], i = '0'+byte(i%10), i/10
        if i == 0 {
            if signed {
                pos--
                buf[pos] = '-'
            }
            return string(buf[pos:])
        }
    }
}

---

2-您可以使用fmt.Sprint(i)(慢)
看到里面:

---

2- You may use fmt.Sprint(i) (Slow)
See inside:

// Sprint formats using the default formats for its operands and returns the resulting string.
// Spaces are added between operands when neither is a string.
func Sprint(a ...interface{}) string {
    p := newPrinter()
    p.doPrint(a)
    s := string(p.buf)
    p.free()
    return s
}

---

3-您可以使用strconv.Itoa(int(i))(快速)
看到里面:

---

3- You may use strconv.Itoa(int(i)) (Fast)
See inside:

// Itoa is shorthand for FormatInt(int64(i), 10).
func Itoa(i int) string {
    return FormatInt(int64(i), 10)
}

---

4-您可以使用strconv.FormatInt(int64(i), 10)(更快)
看到里面:

---

4- You may use strconv.FormatInt(int64(i), 10) (Faster)
See inside:

// FormatInt returns the string representation of i in the given base,
// for 2 <= base <= 36. The result uses the lower-case letters 'a' to 'z'
// for digit values >= 10.
func FormatInt(i int64, base int) string {
    _, s := formatBits(nil, uint64(i), base, i < 0, false)
    return s
}

---

比较&基准测试(具有50000000次迭代):

---

Comparison & Benchmark (with 50000000 iterations):

s = String(i)                       takes:  5.5923198s
s = String2(i)                      takes:  5.5923199s
s = strconv.FormatInt(int64(i), 10) takes:  5.9133382s
s = strconv.Itoa(int(i))            takes:  5.9763418s
s = fmt.Sprint(i)                   takes: 13.5697761s

代码:

package main

import (
    "fmt"
    //"strconv"
    "time"
)

func main() {
    var s string
    i := int32(-2147483648)
    t := time.Now()
    for j := 0; j < 50000000; j++ {
        s = String(i) //5.5923198s
        //s = String2(i) //5.5923199s
        //s = strconv.FormatInt(int64(i), 10) // 5.9133382s
        //s = strconv.Itoa(int(i)) //5.9763418s
        //s = fmt.Sprint(i) // 13.5697761s
    }
    fmt.Println(time.Since(t))
    fmt.Println(s)
}

func String(n int32) string {
    buf := [11]byte{}
    pos := len(buf)
    i := int64(n)
    signed := i < 0
    if signed {
        i = -i
    }
    for {
        pos--
        buf[pos], i = '0'+byte(i%10), i/10
        if i == 0 {
            if signed {
                pos--
                buf[pos] = '-'
            }
            return string(buf[pos:])
        }
    }
}

func String2(n int32) string {
    buf := [11]byte{}
    pos := len(buf)
    i, q := int64(n), int64(0)
    signed := i < 0
    if signed {
        i = -i
    }
    for {
        pos--
        q = i / 10
        buf[pos], i = '0'+byte(i-10*q), q
        if i == 0 {
            if signed {
                pos--
                buf[pos] = '-'
            }
            return string(buf[pos:])
        }
    }
}

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