Difference between var keyword and short declaration operator in Golang

In Golang, variables can be declared using the var keyword or the short declaration operator :=. While both ways allow the programmer to define variables, they have some differences that make them suitable for different scenarios. In this article, we will discuss the difference between the var keyword and the short declaration operator and when to use them.

Var Keyword in Golang

In Golang, the var keyword is used to declare variables with a specified type. It is a way of explicitly declaring the type of the variable. The syntax of the var keyword is as follows −

var variableName variableType

For example, to declare an integer variable, we can use the var keyword in the following way −

var myInt int

The above code declares an integer variable named myInt. It has not been initialized yet, so it will be assigned the zero value of an integer type, which is 0.

The var keyword can also be used to declare multiple variables of the same type −

var x, y, z int

In the above code, three integer variables named x, y, and z have been declared.

Short Declaration Operator in Golang

The short declaration operator := is used to declare and initialize variables in Golang. It is a concise way of declaring variables without explicitly specifying their type. The syntax of the short declaration operator is as follows −

variableName := value

For example, to declare an integer variable and initialize it with a value of 10, we can use the short declaration operator in the following way −

myInt := 10

In the above code, an integer variable named myInt has been declared and initialized with a value of 10. The Go compiler automatically infers the type of the variable based on the value assigned to it.

The short declaration operator can also be used to declare and initialize multiple variables of different types −

x, y, z := 1, 2.5, "hello"

In the above code, three variables named x, y, and z of different types have been declared and initialized in a single line.

Difference between var keyword and short declaration operator

Var Keyword	Short Declaration Operator
Used to declare variables with a specified type	Used to declare and initialize variables without explicitly specifying their type
Variables declared with var keyword can have a default zero value	Variables declared with short declaration operator are initialized with a value provided by the programmer
Cannot be used inside functions to declare and initialize variables	Can be used inside functions to declare and initialize variables
Used when the variable needs to have a specified type or needs to be initialized later in the program	Used when the variable needs to be declared and initialized in a single line and the type can be inferred by the compiler

Conclusion

Both the var keyword and the short declaration operator have their advantages and disadvantages. The var keyword is useful when the programmer wants to declare variables with a specified type or when the variable needs to be initialized later in the program. On the other hand, the short declaration operator is useful when the programmer wants to declare and initialize variables in a single line without explicitly specifying their type. Understanding the differences between these two ways of declaring variables is important for writing efficient and effective code in Golang.