Go json: unsupported value: NaN

1. 简介

除数为浮点数并且值为0时不会引发panic，此时得到的结果是NaN是不可以用来进行数学运算和JSON对象序列化反序列化。

下面是对问题复现。

2. 演示

package main

import (
	"encoding/json"
	"fmt"
)

func main() {
	var i int64 = 0
	var j int64 = 0
	var f float64 = float64(i) / float64(j)
	fmt.Println(f) // Output: NaN

	// JSON
	type Example struct {
		F float64
	}
	data, err := json.Marshal(Example{F: f})
	if err != nil {
		panic(err)
	}
	fmt.Println(string(data))
}

Output

NaN
panic: json: unsupported value: NaN

goroutine 1 [running]:
main.main()
        /Users/yimt/Code/GoProjects/src/hello-go/main.go:20 +0xe9

3. 除0异常

3.1. 正常情况下

正常除数是0会引起panic

package main

import "fmt"

func main() {
	var i int64 = 0
	var j int64 = 0
	fmt.Println(i / j)
}

Output

panic: runtime error: integer divide by zero

goroutine 1 [running]:
main.main()
        /Users/yimt/Code/GoProjects/src/hello-go/main.go:8 +0x11

3.2. 例外情况

除数是0但是没有引起panic

package main

import "fmt"

func main() {
	var i int64 = 0
	var j int64 = 0
	var f float64 = float64(i) / float64(j)
	fmt.Println(f)
}

Output

NaN