Go language variable scope
The scope is the scope of the constant, type, variable, function, or packagerepresented by the declared identifier in the source code.
Go variables in a language can be declared in three places:
The variables defined in the function are called local variables.
Variables defined outside the function are called global variables
Variables in function definitions are called formal parameters
Next, let’s look at local variables, global variables, and formal parametersin detail.
Local variable
The variables declared in the body of the function are called local variables, their scope is only in the body of the function, and the parameters and return value variables are also local variables.
In the following example, the main() function uses local variables a , b , c :
Example
package main
import "fmt"
func main() {
/* Declare local variables */
var a, b, c int
/* Initialization parameters */
a = 10
b = 20
c = a + b
fmt.Printf ("result： a = %d, b = %d and c = %d\\n", a, b, c)
}
The output of the above example is as follows:
result： a = 10, b = 20 and c = 30
Global variable
Variables declared outside the function are called global variables, which can be used in the entire package or even the external package (after being exported).
Global variables can be used in any function, and the following example demonstrates how to use global variables:
Example
package main
import "fmt"
/* Declare global variables */
var g int
func main() {
/* Declare global variables */
var a, b int
/* Initialization parameter */
a = 10
b = 20
g = a + b
fmt.Printf("result： a = %d, b = %d and g = %d\\n", a, b, g)
}
The output of the above example is as follows:
result： a = 10, b = 20 and g = 30
Go language program, the names of global and local variables can bethe same, but local variables within the function are preferred. Examples are as follows:
Example
package main
import "fmt"
/* Declare global variables */
var g int = 20
func main() {
/* Declare local variables */
var g int = 10
fmt.Printf ("result： g = %d\\n", g)
}
The output of the above example is as follows:
result： g = 10
Formal parameter
Formal arguments are used as local variables of the function. Examples are as follows:
Example
package main
import "fmt"
/* Declare global variables */
var a int = 20;
func main() {
/* Declaring local variables in the main function */
var a int = 10
var b int = 20
var c int = 0
fmt.Printf("main()In the function a = %d\\n", a);
c = sum( a, b);
fmt.Printf("main()In the function c = %d\\n", c);
}
/* Function Definition - Adding Two Numbers*/
func sum(a, b int) int {
fmt.Printf("sum() In the function a = %d\\n", a);
fmt.Printf("sum() In the function b = %d\\n", b);
return a + b;
}
The output of the above example is as follows:
In the main() function, a=10
In the sum() function, a=10
B=20 in the sum() function
C=30 in the main() function
Initialize local and global variables
The default values for different types of local and global variables are:
Data type |
Initialize default |
|---|---|
Int |
0 |
Float32 |
0 |
Pointer |
Nil |