Difference between var keyword and short declaration operator in Golang
Last Updated : 11 Mar, 2023
A variable is a storage location or place holder used for holding the value. It allows us to manipulate and retrieve the stored information. There are two ways to declare the variables in Golan which are as follows:
- var varName type = value
- varName := value
Difference between var keyword and short declaration operator
| var keyword | short declaration operator |
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| var is a lexical keyword present in Golang. | := is known as the short declaration operator. |
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| It is used to declare and initialize the variables inside and outside the functions. | It is used to declare and initialize the variables only inside the functions. |
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| Using this, variables have generally package level or global level scope. It can also have local scope. | Here, variables has only local scope as they are only declared inside functions. |
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| Declaration and initialization of the variables can be done separately. | Declaration and initialization of the variables must be done at the same time. |
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| It is mandatory to put type along with the variable declaration. | There is no need to put type. If you, it will give error. |
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Example 1: In this program you can see the myvariable1 is declared using var keyword and it has local scope. myvariable2 is also declared using var keyword along with type int but there is no initialization has been done. So it will take the default value of int type i.e. zero(you can see in the output). myvariable3 is declared and initialized using short variable declaration operator and it has local scope.
Go // Go program to show the use of var lexical // keyword and short declaration operator package main import ( "fmt"; ) func main() { // using var keyword to declare // and initialize the variable var myvariable1 = 100 fmt.Println(myvariable1) // using var keyword to declare // the variable along with type // type is mandatory while declaration var myvariable2 int fmt.Println(myvariable2) // using short variable declaration myvariable3 := 200 fmt.Println(myvariable3) } Output:
100 0 200
Example 2: In this program you can see the myvariable1 is declared using var keyword and it has global scope. myvariable2 is also declared using var keyword along with type int but there is no initialization has been done. So it will take the default value of int type i.e. zero(you can see in the output). myvariable3 is declared and initialized using short variable declaration operator and it has local scope.
Go // Go program to show the use of var lexical // keyword and short declaration operator package main import ( "fmt" ) // using var keyword to declare // and initialize the variable // it is package or you can say // global level scope var myvariable1 = 100 func main() { // accessing myvariable1 inside the function fmt.Println(myvariable1) // using var keyword to declare // the variable along with type var myvariable2 int fmt.Println(myvariable2) // using short variable declaration myvariable3 := 200 fmt.Println(myvariable3) } Output:
100 0 200
Example 3: In this program you can see the myvariable1 is declared using var keyword and it has global scope. myvariable2 is also declared using var keyword along with type int but there is no initialization has been done. So it will take the default value of int type i.e. zero(you can see in the output). myvariable3 is declared and initialized using short variable declaration operator outside the function which is not allowed and hence gives error.
Go // Go program to show the use of var lexical // keyword and short declaration operator package main import ( "fmt" ) // using var keyword to declare // and initialize the variable // it is package or you can say // global level scope var myvariable1 = 100 // using short variable declaration // it will give an error as it is not // allowed outside the function myvariable3 := 200 func main() { // accessing myvariable1 inside the function fmt.Println(myvariable1) // using var keyword to declare // the variable along with type var myvariable2 int fmt.Println(myvariable2) fmt.Println(myvariable3) } Error:
./prog.go:18:1: syntax error: non-declaration statement outside function body