如何在Go中测试浮点数是否为整数？

Question

I originally tried this, however the % operator isn't defined for float64.

func main(){
    var a float64
    a = 1.23
    if a%1 == 0{
        fmt.Println("yay")
    }else{
        fmt.Println("you fail")
    }
}

Answer 1

Assuming your numbers will fit into an int64, you can just compare the float value with a converted integer value to see if they're the same:

if a == float64(int64(a)) {
    fmt.Println("yay")
} else {
    fmt.Println("you fail")
}

Otherwise you can use the math.Trunc function detailed here, with something like:

if a == math.Trunc(a) {
    fmt.Println("yay")
} else {
    fmt.Println("you fail")
}

That one should work within the entire float64 domain.