Turbo Pascal,the world-standard Pascal compiler, adds Object-Oriented Programming. Combining the Simplicity of Apple's Object Pascal language with The Power and efficiency of C to create Turbo Pascal,the object-oriented programming language for the rest of us.
You have seen a basic structure of pascal program, so it will be easy to understand other basic building blocks of the pascal programming language.
A variable definition is put in a block beginning with a var keyword, followed by definitions of the variables as follows:
Pascal variables are declared outside the code-body of the function which means they are not declared within the begin and end pairs, but they are declared after the definition of the procedure/function and before the begin keyword. For global variables, they are defined after the program header.
In Pascal, a procedure is set of instructions to be executed, with no return value and a function is a procedure with a return value. The definition of function/procedures will be as follows −
The multiline comments are enclosed within curly brackets and asterisks as {* ... *}. Pascal allows single-line comment enclosed within curly brackets { ... }.
Pascal is a case non-sensitive language, which means you can write your variables, functions and procedure in either case. Like variables A_Variable, a_variable and A_VARIABLE have same meaning in Pascal.
Pascal programs are made of statements. Each statement specifies a definite job of the program. These jobs could be declaration, assignment, reading data, writing data, taking logical decisions, transferring program flow control, etc.
For example −
The statements in Pascal are designed with some specific Pascal words, which are called the reserved words. For example, the words, program, input, output, var, real, begin, readline, writeline and end are all reserved words.
Following is a list of reserved words available in Pascal.
and | array | begin | case | const |
div | do | downto | else | end |
file | for | function | goto | if |
in | label | mod | nil | not |
of | or | packed | procedure | program |
record | repeat | set | then | to |
type | until | var | while | with |
The Pascal character set consists of −
All upper case letters (A-Z)
All lower case letters (a-z)
All digits (0-9)
Special symbols - + * / := , . ;. () [] = {} ` white space
The entities in a Pascal program like variables and constants, types, functions, procedures and records, etc., have a name or identifier. An identifier is a sequence of letters and digits, beginning with a letter. Special symbols and blanks must not be used in an identifier.