Conditional assignment

[llenae...@gmail.com]

Hi there, Go (and programming in general) newbie here. I'm trying to assign the value of a variable based on a condition. I've tried 2 different ways, none of them worked: 

package main

import "fmt"

func main() {

a := 40

if a >= 35 {

title := "sir"

} else if a <= 35 {

title := "dude"

}

fmt.Printf(title)

}

This one throws the error:

# command-line-arguments

./main.go:14: undefined: title

So I know this is related to the scope of title. I've tried also with the switch statement, same result.

func main() {

a := 40

switch {

case a >= 35:

title := "sir"

case a <= 35:

title := "dude"

}

fmt.Printf(title)

}

So my question is how can I do that? meaning, how can I assign a variable based on a condition. Thanks. 

[Christian von Kietzell]

You have to declare "title" before the if statement and use the '=' assignment operator:

var title string

if a >= 35 {
        title = "sir"

} else if a < 35 {

        title = "dude"

}

Chris

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[Jan Mercl]

On Tue, Apr 28, 2015 at 2:30 PM <llenae...@gmail.com> wrote:

> So my question is how can I do that? meaning, how can I assign a 

> variable based on a condition. 

If you want to assign a value to the same variable from different scopes, use the assignment operator '='.

':=' is not an assignment operatos. It's a short variable declaration. Thus you're declaring different, although same named, variables in different scopes. (And the throwing them away which the compiler does not allow.)

Something like this might be the solution: http://play.golang.org/p/8NzTB7Z1u3

-j

[llenae...@gmail.com]

Thanks a lot Christian. Problem solved. 

[Carlos Castillo]

I find that after using go for a while (and doing a lot of error checking) I tend to do the following: http://play.golang.org/p/2Gn8oIr4lh

[Volker Dobler]

The problem with your code has nothing to do with "conditional assignment".

You first have to understand the difference between a short variable declaration

done with the := operator and an assignment done with =.

Doing title := "sir" declares a new variable title in the current scope (and determines

it type from the right hand side). It is equivalent to var title string; title = "sir"

which splits these two things: Declare a variable and assign a value.

Remember: In Go you cannot declare a variable and not use it.  All your

title := "sir" declare new variables an never use it in the scope declared.

Declare your variable first (var title string) and just assign it's value with title = "sir".

It dosn't matter if you use a switch or a if/else.

V.