Undefined variable golang [duplicate] - go

Question

This question already has answers here:
Variable scope inside if statements
(2 answers)
Closed 4 years ago.
Can someone tell me why num is undefined :: Here is go playground link also you can check this code here:
https://play.golang.org/p/zR9tuVTJmx-
package main
import "fmt"
func main() {
if 7%2 == 0 {
num := "first"
} else {
num := "second"
}
fmt.Println(num)
}

Answer 1

That's something related to lexical scoping, look over here for an introduction
Basically any variable within {}curly braces is considered as new variable, within that block.
so In the above program you have created two new variables.
Block is something like enclosing a around a variable.
If you are outside a block, you cannot see it. you need to be inside the block in order to see it.
package main
import "fmt"
func main() {
if 7%2 == 0 {
// you are declaring a new variable,
num := "first"
//this variable is not visible beyond this point
} else {
//you are declaring a new variable,
num := "second"
//this variable is not visible beyond this point
}
// you are trying to access a variable, which is declared in someother block,
// which is not valid, so undefined.
fmt.Println(num)
}
What you are looking for is this:
package main
import "fmt"
func main() {
num := ""
if 7%2 == 0 {
//num is accessible in any other blocks below it
num = "first"
} else {
num = "second"
}
//num is accessible here as well, because we are within the main block
fmt.Println(num)
}