Convert integers to string

In Go, you can’t directly cast an int to a string as you might in more loosely typed languages. Instead, you’ll need to format your integer as a string using one of several options.

This snippet will show you how to use the strconv and fmt packages to format integers as strings.

Using strconv.Itoa

The simplest way to convert an integer to a string is by using the strconv.Itoa function. This function will take your integer and format it as a base 10 integer.

“Itoa” stands for “Integer to ASCII”, based on a common C function of the same name.

See the example below:

package main

import (
	"fmt"
	"strconv"
)

func main() {
	i := 12345
	s := strconv.Itoa(i)
	fmt.Println("string:", s)
}

In this example the i integer is converted to string s using strconv.Itoa and then printed to stdout.

Using strconv.FormatInt

If you want to format your integer in a different base, strconv.FormatInt is the right choice.

For example, you can format your integer in binary (base 2) as follows:

package main

import (
	"fmt"
	"strconv"
)

func main() {
	i := int64(5) // strconv.FormatInt requires int64.
	s := strconv.FormatInt(i, 2)
	fmt.Println("string:", s)
}

Bases up to base 36 are supported, if an invalid base is provided the function will panic.

Using the fmt package

So far we’ve only converted the integer to a string without including more text. But what if you want to include more?

You should take a look at the fmt package.

For example, the fmt.Sprintf function allows you to specify a layout string with a placeholder for the integer.

package main

import (
	"fmt"
)

func main() {
	i := 12345
	s := fmt.Sprintf("%d is the number", i)
	fmt.Println(s)
}

In this example, %d is the placeholder for a base 10 integer.

Other integer placeholders include:

In the fmt package documentation you can also find several flags that enable extra options for these placeholders.