Quick start manual

4-28 Delphi Language Guide
Declarations and statements
Examples of while statements include
while Data[I] <> X do I := I + 1;
while I > 0 do
begin
if Odd(I) then Z := Z * X;
I := I div 2;
X := Sqr(X);
end;
while not Eof(InputFile) do
begin
Readln(InputFile, Line);
Process(Line);
end;
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
for counter := initialValue to finalValue do statement
or
for counter := initialValue downto finalValue do statement
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 for...to
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 for...to
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.