## Formatting numbers

• If the numbers are converted to the string, they usually need to be reasonably formatted. The formatting of a number means the number is printed with a given number, made up of digits and decimals. The representation of a value can also be chosen. A closely related problem with this, however, is the localization of number formatting. For example, some languages use comma-separated zeros.

## Create the format.go file with the following content:

``````        package main

import (
"fmt"
)

var integer int64 = 32500
var floatNum float64 = 22000.456

func main() {

// Common way how to print the decimal
// number
fmt.Printf("%d \n", integer)

// Always show the sign
fmt.Printf("%+d \n", integer)

// Print in other base X -16, o-8, b -2, d - 10
fmt.Printf("%X \n", integer)
fmt.Printf("%#X \n", integer)

fmt.Printf("%010d \n", integer)

fmt.Printf("% 10d \n", integer)

fmt.Printf("% -10d \n", integer)

// Print floating
// point number
fmt.Printf("%f \n", floatNum)

// Floating-point number
// with limited precision = 5
fmt.Printf("%.5f \n", floatNum)

// Floating-point number
// in scientific notation
fmt.Printf("%e \n", floatNum)

// Floating-point number
// %e for large exponents
// or %f otherwise
fmt.Printf("%g \n", floatNum)

}

``````

output:

``````sangam:golang-daily sangam\$ go run format.go
32500
+32500
7EF4
0X7EF4
0000032500
32500
32500
22000.456000
22000.45600
2.200046e+04
22000.456

``````

## Create the file localized.go with the following content:

``````        package main

import (
"golang.org/x/text/language"
"golang.org/x/text/message"
)

const num = 100000.5678

func main() {
p := message.NewPrinter(language.English)
p.Printf(" %.2f \n", num)

p = message.NewPrinter(language.German)
p.Printf(" %.2f \n", num)
}

``````

output:

``````sangam:golang-daily sangam\$ go run localized.go
100,000.57
100.000,57
sangam:golang-daily sangam\$

``````

## How it works…

• The code example shows the most commonly used options for integers and floating-point numbers.
• Note:The formatting in Go is derived from C’s printf function. The so-called verbs are used to define the formatting of a number. The verb, for example, could be %X, which in fact is a placeholder for the value.
• Besides the basic formatting, there are also rules in formatting that are related to the local manners. With formatting, according to the locale, the package golang.org/x/text/message could help. See the second code example in this recipe. This way, it is possible to localize the number formatting.

## There’s more…

• For all formatting options, see the fmt package. The strconv package could also be useful in case you are looking to format numbers in a different base. The following recipe describes the possibility of number conversion, but as a side effect, the options of how to format numbers in a different base are presented