Keywords and Basic Syntax in Pascal

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In the previous article, Mytour introduced the structure of a Pascal program, making it easier for you to understand other basic blocks of the Pascal programming language. In this article, Mytour provides information on keywords and basic syntax in Pascal.

The Pascal programming language does not distinguish between uppercase and lowercase letters. This means you can write variables, functions, and procedures using both uppercase and lowercase letters. Below are detailed insights into keywords and basic syntax in Pascal.

Variable

Variables (variable) are placed within a block starting with the keyword 'var,' followed by variable definitions as follows:

var

A_Variable, B_Variable ... : Variable_Type;

Pascal variables are declared within the code section of a function, meaning they should not be declared within the opening and closing pairs but after defining procedures/functions and before the start keyword. For global variables, they are defined after the program header.

Function (function) / Procedure (procedure)

In Pascal, a procedure establishes instructions to be executed, with no return value, while a function is a procedure with a return value. Definitions for function/procedure are as follows:

Function Func_Name(params...) : Return_Value;

Procedure Proc_Name(params...);

Comment

Multi-line comments are enclosed in curly braces and asterisks, denoted as {* ... *}. Pascal allows single-line comments enclosed in curly braces {...}.

{* This is a multi-line comment

And it will extend over several lines. *}

{ This is a single-line comment in Pascal }

Case Sensitivity

The Pascal programming language does not distinguish between uppercase and lowercase letters. This means you can write variables, functions, and procedures in both uppercase and lowercase. For example, variables A_Variable, a_variable, and A_VARIABLE all have significance in Pascal.

Pascal Commands

Pascal programs are constructed from commands. Each command defines a specific task of the program. These tasks can include declarations, assignments, reading data, writing data, program control flow, and more.

For example:

readln(a, b, c);

s := (a + b + c)/2.0;

area := sqrt(s * (s - a)*(s-b)*(s-c));

writeln(area);

Reserved Keywords in Pascal

Commands in Pascal are designed with specific Pascal keywords, known as reserved words. For instance, word (keyword), program (program), input (input), output (output), var, real, begin, readline, writeline, and end are all reserved keywords in Pascal.

Below is a list of reserved keywords available in Pascal.

Character Set and Identifiers in Pascal

The Pascal character set includes:

- All uppercase letters (A-Z).

- All lowercase letters (a-z).

- All digits (0-9).

- Special symbols - + * /: =,. ; () [] = {} and whitespace

Entities in a Pascal program such as variables, constants, types, functions, procedures, and records will have a name or an identifier. An identifier is a sequence of letters and digits, starting with a letter. Special symbols and whitespace are not used in identifiers.

By grasping the fundamental keywords and syntax in Pascal, it is hoped that you will gain a better understanding of this widely used high-level programming language. Share your thoughts with Mytour.

Frequently Asked Questions

What are the key features of the Pascal programming language's syntax?

Pascal's syntax features include case insensitivity, the use of keywords for variable declarations, and specific structures for defining functions and procedures. Variables are declared after the program header, with commands following a defined format. Comments can be single or multi-line, enhancing code readability.

How are variables declared and used within a Pascal program?

In Pascal, variables are declared using the 'var' keyword, followed by their names and types. They must be placed in the code section of a function after defining procedures. This organization allows for clear structure and efficient use within the program's execution flow.

What is the difference between functions and procedures in Pascal?

A function in Pascal is a type of procedure that returns a value, while a procedure does not return any value. Both are defined using specific syntax, with functions typically used for computations that require a return value, enhancing code modularity.

What types of comments are allowed in Pascal programming?

Pascal allows both single-line comments, denoted with curly braces {...}, and multi-line comments enclosed in curly braces and asterisks {...}. These comments are essential for documenting code and making it easier for others to understand the programmer's intentions.

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