For Statements

A for statement, unlike a repeat or while statement, requires you to specify explicitly the number of iterations you want the loop to go through. The syntax of a for statement is forcounter := initialValuetofinalValuedostatement or forcounter := initialValuedowntofinalValuedostatement where

  • counter is a local variable (declared in the block containing the for statement) of ordinal type, without any qualifiers.
  • initialValue and finalValue are expressions that are assignment-compatible with counter.
  • statement is a simple or structured statement that does not change the value of counter.

The for statement assigns the value of initialValue to counter, then executes statement repeatedly, incrementing or decrementing counter after each iteration. (The syntax increments counter, while the for...downto syntax decrements it.) When counter returns the same value as finalValue, statement is executed once more and the for statement terminates. In other words, statement is executed once for every value in the range from initialValue to finalValue. If initialValue is equal to finalValue, statement is executed exactly once. If initialValue is greater than finalValue in a statement, or less than finalValue in a for...downto statement, then statement is never executed. After the for statement terminates (provided this was not forced by a Break or an Exit procedure), the value of counter is undefined.

For purposes of controlling execution of the loop, the expressions initialValue and finalValue are evaluated only once, before the loop begins. Hence the statement is almost, but not quite, equivalent to this while construction:

begin counter := initialValue; while counter <= finalValue do begin

The difference between this construction and the statement is that the while loop reevaluates finalValue before each iteration. This can result in noticeably slower performance if finalValue is a complex expression, and it also means that changes to the value of finalValue within statement can affect execution of the loop.

Examples of for statements:

for I := 2 to 63 do if Data[I] > Max then Max := Data[I];

for I := ListBox1.Items.Count - 1 downto 0 do

ListBox1.Items[I] := UpperCase(ListBox1.Items[I]);


Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

Get My Free Ebook

Post a comment