Re: Unable to access a variable declared inside an if statement (Error: is shadowing variable)

[BoQsc via Digitalmars-d-learn]

On Wednesday, 27 May 2020 at 11:13:09 UTC, Simen Kjærås wrote:

On Wednesday, 27 May 2020 at 11:03:51 UTC, BoQsc wrote:

I'm lacking knowledge on how to achieve what I want and getting an error. What is the correct way to do what I tried to achieve in this code? Everything was intuitive until I started to add notice variable to the writeln. Rdmd says variable `notice` is shadowing variable.

                if (driveLetter.exists){
                        auto directory = "/Backup";
                        if ((driveLetter ~ directory).exists){
                                auto notice = "Backup directory exists.";
                                
                        }
                        writeln(driveLetter, notice);
                }

Variables only live in a specified scope, starting from where they are declared, and ending when they reach the '}' indicating the end of said scope.

In you case, 'notice' only lives inside the if ((driveLetter ~ directory).exists) scope, and doesn't exist outside. In order to fix this, you will need to declare it outside:

    if (driveLetter.exists) {
        auto directory = "/Backup";
        auto notice = "Backup directory does not exist.";
        if ((driveLetter ~ directory).exists) {
            notice = "Backup directory exists.";
        }
        writeln(driveLetter, notice);
    }

This also makes it clearer what value 'notice' will have when the backup directory doesn't exist - in your case you haven't assigned it any value in that case.

--
  Simen

That's correct. Thanks Simen.

import std.stdio : writeln;
import std.file;
void main(){

        auto drivesLetters = [
                "A:", "I:", "Q:", "Y:",
                "B:", "J:", "R:", "Z:",
                "C:", "K:", "S:",                 "D:", "L:", "T:",
                "E:", "M:", "U:",
                "F:", "N:", "V:",
                "G:", "O:", "W:",
                "H:", "P:", "X:",
        ];
        
        foreach (string driveLetter; drivesLetters) {
                if (driveLetter.exists) {
                                auto notice = "";
                                if ((driveLetter ~ "/Boot").exists) {
                                        notice ~= "\\Boot directory exists";
                                        notice ~= " ";
                                }
                                if ((driveLetter ~ "/Windows").exists) {
                                        notice ~= "\\Windows folder exists";
                                        notice ~= " ";
                                }
                                writeln(driveLetter, notice);
                        }
                
        }

        
}