Delphi Basics : Do command

DelphiBasics

Do
Keyword

Defines the start of some controlled action

keyword Do(1. for Variable := Expression to Expression do Statement;
2. while Expression do Statement
3. try Statements except on ExceptionClass do Statement; end;
4. with Expression do Statement

Description

The Do keyword is always a part of one of the shown 4 control types. It precedes the Statements section of the control action.

Related commands

Begin		Keyword that starts a statement block
End		Keyword that terminates statement blocks
Except		Starts the error trapping clause of a Try statement
For		Starts a loop that executes a finite number of times
Repeat		Repeat statements until a ternmination condition is met
Try		Starts code that has error trapping
While		Repeat statements whilst a continuation condition is met
With		A means of simplifying references to structured variables

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Example code : Show singles and block do statement blocks

var
  i : Integer;

begin
  // A for statement - the do keyword precedes a single statement
  for i := 1 to 3 Do
    ShowMessage('For loop, i = '+IntToStr(i));

  // A while statement - the do precedes a statement block
  while i < 6 Do
  begin
    ShowMessage('While loop, i = '+IntToStr(i));
    Inc(i);
  end;
end;

Show full unit code

  For loop, i = 1
  For loop, i = 2
  For loop, i = 3
  While loop, i = 4
  While loop, i = 5