Variable Declarations

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TMT Pascal Language Description

Pascal Language Structure

Declarations

Variable Declarations

Variables store data during program execution. A variable declaration is preceded by the var reserved word.

  var identifier [,identifier]: Identifiertype;

Identifier is the actual name of the variable defined. Identifiertype specifies the type of the variable. Variables, unlike constants, are not initialized. Their content prior to initialization is undefined. It is also possible to specify the absolute address of a variable. Following the Identifiertype specify the Absolute reserved word.

  var identifier [,identifier]: Identifiertype absolute address;

Address may be either an identifier or an integer number indicating an offset. If Address is an identifier then TMT Pascal computes it's offset. Absolute maps the variable to the address following the Absolute statement. This identifier must be declared prior to using Absolute. If a variable is the absolute of another, both address the same data however the types may be different. The following are examples of variable declarations.

const
  BuffSize = 900000;  // 900K

var
  HugeBuff : array [0..BuffSize] of Char;
  i,j,k,l  : Integer;
  Buffptr  : Longint;
  p        : Pointer absolute Buffptr;
  Alpha    : Char;

The absolute may refer to fields of records and objects. Also, the address of a global record/object field can be used within the initialization of typed constants. Furthermore one can use recursive initialization:

type
  rec = record
    next:    ^rec;
    buffer:  array [1..10] of char;
    buf_adr: pointer;
  end;
 
const
  cyclic: rec = (next: @cyclic; buf_adr: @cyclic.buffer);


Constant Declarations	Table of Content	Local Block Declarations

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