How Can I Check if a Go float64 Represents a Whole Number?

Determining Integer Values from Floating Point Numbers in Go

In Go, determining if a float64 represents a whole number can pose a challenge. The modulo operator (%) cannot be used directly on floats.

Solution 1: Comparing Float64 with Integer Equivalent

If your numbers can fit into an int64, consider comparing the float with its converted integer value:

if a == float64(int64(a)) { ... }

Solution 2: Utilizing math.Trunc

For the entire float64 domain, you can use the math.Trunc function:

if a == math.Trunc(a) { ... }

For example:

package main

import (
    "fmt"
    "math"
)

func main() {
    var a float64 = 2.00
    if a == math.Trunc(a) {
        fmt.Println("yay")
    } else {
        fmt.Println("you fail")
    }
}

This code correctly outputs "yay" when a is set to 2.00, indicating that it is a whole number.

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