How do I check whether a string exists in an array?

Question

I have this code:

var
  ExtString: string;
const
  Extensions : array[0..4] of string = ('.rar', '.zip', '.doc', '.jpg', '.gif');

if ExtString in Extensions then

On the last line, I get an error:

[DCC Error] E2015 Operator ('then') not applicable to this operand type

I think I can not do this, so how can I properly perform my task?

Answer 1

As you have found you can't check for a String in an Array of String, using in.

You could use this function instead of the if statement.

function StrInArray(const Value : String;const ArrayOfString : Array of String) : Boolean;
var
 Loop : String;
begin
  for Loop in ArrayOfString do
  begin
    if Value = Loop then
    begin
       Exit(true);
    end;
  end;
  result := false;
end;

You can call it like this.

if StrInArray(ExtString,Extensions) then

The StrUtils.pas has this already defined.

function MatchStr(const AText: string; const AValues: array of string): Boolean; 

Answer 2

Initialise a TStringList instance from the constant array and use IndexOf().