How Do I Change Data Type in Golang?


Scott Campbell

Changing the data type in Golang is a common task that developers often encounter. Whether you need to convert an integer to a string or vice versa, or perhaps modify a variable’s type to fit the requirements of a specific function, Golang provides various methods for handling data type conversions. In this tutorial, we will explore some of the most commonly used techniques for changing data types in Golang.

Converting Numeric Types

In Golang, converting between numeric types is straightforward. Let’s say you have an integer variable x and you want to convert it to a float64. You can do this by using the float64() function:

var x int = 10
var y float64 = float64(x)

The float64() function takes the value of x and converts it into a float64 data type. You can apply this technique to any numeric type conversion.

Converting Strings to Numbers and Vice Versa

Golang also provides functions for converting strings to numbers and vice versa. Let’s assume you have a string representation of an integer and you want to convert it into an actual integer value. You can use the Atoi() function from the strconv package:

import (

func main() {
    str := "42"
    num, _ := strconv.Atoi(str)

The Atoi() function takes a string as input and returns an integer value. In our example, the variable num will be assigned the value 42.

If you want to convert a number to a string, you can use the Itoa() function:

func main() {
num := 42
str := strconv.Itoa(num)

The Itoa() function converts an integer to its string representation. In this case, the variable str will be assigned the value “42”.

Converting Between Structs and JSON

Golang provides built-in support for converting between structs and JSON. This is particularly useful when working with APIs or storing data in databases. To convert a struct to JSON, you can use the encoding/json package:

import (

type Person struct {
    Name string
    Age  int

func main() {
    person := Person{"John Doe", 30}
    jsonBytes, _ := json.Marshal(person)
    jsonString := string(jsonBytes)

In this example, we define a struct called Person, which has two fields: Name and Age. We then create an instance of the Person struct and convert it to JSON using the Marshal() function from the encoding/json package. The resulting JSON string is stored in the variable jsonString.

To convert JSON back to a struct, you can use the Unmarshal() function:

func main() {
jsonString := `{“Name”:”John Doe”,”Age”:30}`
var person Person
json.Unmarshal([]byte(jsonString), &person)

fmt.Println(person.Name, person.Age)

In this example, we define the same Person struct. We then have a JSON string stored in the variable jsonString. Using the Unmarshal() function, we convert the JSON string to a struct and store it in the variable person.


Golang provides several methods for changing data types. Whether you need to convert numeric types, convert strings to numbers or vice versa, or work with structs and JSON, Golang’s standard library offers convenient functions for these operations. By leveraging these techniques, you can manipulate data types effectively and efficiently in your Golang programs.

I hope this tutorial has provided you with a solid understanding of how to change data types in Golang. Experiment with these techniques and explore further possibilities as you continue your journey with Golang development!

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