What is Global Variables in Golang

by

Global variables in Golang are declared outside of any function and accessible from any function within the same package.

Global variables can be shared across the entire package, and they are frequently used to store data required by multiple functions or to share data between different parts of the program.

How to create a global variable in Golang?

You can create a global variable in Golang by declaring a variable outside any function. Global variables are declared at the program’s top before the main() function.

Example

package main

import "fmt"

var globalVar int = 21

func main() {
  fmt.Println("The value of globalVar is:", globalVar)
}

Output

The value of globalVar is: 21

In this example, the global variable globalVar is declared at the package level and can be accessed by the main function.

The value of globalVar can be changed by any function in the same package, which makes it a powerful mechanism for sharing data between different parts of the program.

Global variable and Local variable

The main difference between global and local variables in Golang is that a global variable is a variable that is declared outside of any function and accessible from any function within the package. In contrast, a local variable is a variable that is declared within a function and can only be accessed within that function.

Global variables store the data needed by multiple functions or provide a way of sharing data between different program parts. In contrast, local variables store the data detailed to a single function and are not needed by other functions.

package main

import "fmt"

var globalVar int = 21

func main() {
  fmt.Println("The value of global variable is:", globalVar)
  localVar := 19
  fmt.Println("The value of local variable is:", localVar)
}

Output

The value of global variable is: 21
The value of local variable is: 19

In this example, the globalVariable is declared at the package level and is accessible by the main() function.

The localVariable is declared within the main() function and can only be accessed within that function.

Pros and Cons of global variables in Go

Pros

Global variables can be used to share data between functions or packages, providing a convenient way of storing data that multiple functions need.

Cons

Global variables make code harder to read and maintain, leading to subtle bugs and difficulty tracking data flow through a program.

FAQ

How do you declare a global variable in Go?

You can declare a global variable in Go and must declare the variable outside any function. For example, var globalVar int = 19 is declared a global variable.

What is the scope of a global variable in Go?

The scope of a global variable in Go is the entire package. Therefore, any function within the same package can access and modify the value of a global variable.

Can global variables share data between functions or packages in Go?

Yes, global variables can be used to share data between functions or packages in Go.

When should I use global variables in Go?

It would be best to use global variables in Go when you need to share data between functions or packages, so it’s often better to pass the data as arguments, return values, or use structs or other data structures.

Final thoughts

Every Go global variable is defined at the top of the function. Global variables are defined as outside functions in the Golang. Therefore, changes to the global variable in one function do not affect the other. We can reassign and redefine the global variable in functions.

That’s it.

Leave a Comment