英文:
Negative zero literal in golang
问题
IEEE754支持负零。但是这段代码
a := -0.0
fmt.Println(a, 1/a)
输出
0 +Inf
而我期望的是
-0 -Inf
其他基于IEEE754的编程语言允许你创建负零字面量
Java:
float a = -0f;
System.out.printf("%f %f", a, 1/a); // 输出 "-0.000000 -Infinity"
C#:
var a = -0d;
Console.WriteLine(1/a); // 输出 "-Infinity"
Javascript:
var a = -0;
console.log(a, 1/a); // 输出 "0 -Infinity"
但是我在Go中找不到相应的写法。
在Go中如何表示负零字面量？
英文:
IEEE754 supports the negative zero.
But this code
a := -0.0
fmt.Println(a, 1/a)
outputs
0 +Inf
where I would have expected
-0 -Inf
Other languages whose float format is based on IEEE754 let you create negative zero literals
Java :
float a = -0f;
System.out.printf("%f %f", a, 1/a); // outputs "-0,000000 -Infinity"
C# :
var a = -0d;
Console.WriteLine(1/a); // outputs "-Infinity"
Javascript :
var a = -0;
console.log(a, 1/a); // logs "0 -Infinity"
But I couldn't find the equivalent in Go.
How do you write a negative zero literal in go ?
答案1
得分: 11
有一个已注册的问题。
并且它恰好提供了一种解决方案：
a := math.Copysign(0, -1)
这并不是很糟糕，因为它显然是指由IEEE754定义的标准copysign函数。
但这意味着你需要导入一个包，对于（尽管是次要且罕见的）需求来说，这仍然显得太重了。
英文:
There is a registered issue.
And it happens to give a kind of solution :
a := math.Copysign(0, -1)
It's not so bad as it obviously refers to the standard copysign function defined by IEEE754.
But this means you need to import a package and this still looks much too heavy for the (admittedly minor and rare) need.
答案2
得分: 6
package main
import (
"fmt"
"math"
)
func main() {
a := 1. / math.Inf(-1)
fmt.Println(a, 1/a)
}
英文:
package main
import (
"fmt"
"math"
)
func main() {
a := 1. / math.Inf(-1)
fmt.Println(a, 1/a)
}
(Also here)
Output:
-0 -Inf
答案3
得分: 0
我刚刚尝试了一下，对我来说似乎可以工作。
package main
import (
"fmt"
)
func main() {
zero := float64(0)
neg_zero := -zero
fmt.Println(zero, neg_zero)
}
尽管当我执行neg_zer0 := - float64(0)时，它并不像预期的那样工作。
英文:
I just tried out this and it seems to work for me .
package main
import (
"fmt"
)
func main() {
zero := float64(0)
neg_zero := -zero
fmt.Println(zero, neg_zero)
}
Though it does not work as expected when I do neg_zer0 := - float64(0)
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