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Table of Contents
2. TMT Pascal Language Description
2.2. Pascal Language Structure
2.2.7. Declarations
2.2.7.5. Local Block Declarations
2.2.7.5. Local Block
Declarations
It is very often necessary to declare a local variable with a short life-span.
One has to do this at the declaration part of a program or in the procedure
body. This is not always convenient, especially if there is a huge program
with a complicated algorithm. For that case a special construction has been
added in TMT Pascal. It is called a Local or Nested Block. Such a block is an
ordinary compound statement which begins with the new reserved word
declare and consists of two parts - declaration and execution:
declare
<declaration part>
begin
<execution part>
end;
This statement can be used in any place where a structured statement can be
placed.
Example:
program DeclDemo;
var
b: Integer;
begin
declare
// first local block
var
a: Integer;
procedure pr_int(a: Integer);
var
i: Integer;
begin
for i := 1 to a do
declare
//second local block
var
k: Integer;
begin
k := a div i;
Writeln(a, ' div ', i, ' = ', k);
end;
end;
begin
a := 1;
Writeln(a);
b := 10;
pr_int(b);
end
end.
This example contains two local blocks one of them is in the program body
and another is in the routine body. The first local block declares variable
a and procedure pr_int, the second declares one local variable
k. It should be understood that the scope of 'a' and pr_int
is the interior of the "first local block," and the scope of
k is the interior of the "second local block."
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