Golang : Display float in 2 decimal points and rounding up or down
We will cover 2 items for this tutorial.
First, we will learn how to display a float number in decimal points with the fmt.Printf()
function. The %0.2f
inside fmt.Printf()
function tells Golang to display up to 2 decimal points. To increase the precision, simply adjust the number from %0.2f
to %0.#f
. # being the number of digits to display the after the decimal point.
Next, Golang math package lacks of functions to do rounding on float numbers. The code example below has 3 functions - one to do rounding, next for rounding up and another to do rounding down for a float value.
Here you go!
package main
import (
"fmt"
"math"
)
func Round(input float64) float64 {
if input < 0 {
return math.Ceil(input - 0.5)
}
return math.Floor(input + 0.5)
}
func RoundUp(input float64, places int) (newVal float64) {
var round float64
pow := math.Pow(10, float64(places))
digit := pow * input
round = math.Ceil(digit)
newVal = round / pow
return
}
func RoundDown(input float64, places int) (newVal float64) {
var round float64
pow := math.Pow(10, float64(places))
digit := pow * input
round = math.Floor(digit)
newVal = round / pow
return
}
func main() {
var f float64 = 123.123456
fmt.Printf("%0.2f \n", f)
fmt.Printf("%0.2f \n", Round(f)) // round half
fmt.Printf("%0.2f \n", RoundUp(f, 2))
fmt.Printf("%0.2f \n", RoundDown(f, 2))
}
NOTE : Change value of f to -123.123456
and see how it goes.
Output :
123.12
123.00
123.13
123.12
References :
http://golang.org/pkg/math/#Ceil
By Adam Ng
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