1. Structured Programming
Language
ITSS113

2. Lecture-1 : INTRODUCTION
Learning Objectives:
To provide brief history of COBOL
To learn the capabilities and limitations of COBOL
To present the program layout of COBOL
To discuss the structure of a COBOL program
To determine the difference between COBOL Literal Set, COBOL Words, COBOL Literals

3. Introduction to COBOL COBOL Common Business Oriented Language
A third-generation programming language,
Was one of the earliest high-level programming languages; still widely used today.
First proposed in 1959 by the Conference on Data Systems Languages (CODASYL).
Three ANSI standards for COBOL have been produced in 1968, 1974 and 1985.
Object-oriented COBOL is the fourth edition in the continuing evolution of ANSI/ISO standard COBOL.

4. Underlining Philosophy
Like the name suggests, COBOL was meant to be ‘common’ or compatible among a significant group of manufacturers
COBOL is designed for developing business, typically file-oriented, applications, and is not designed for writing systems programs.
Primary domain in business, finance, and administrative systems for companies and governments.

5. Pro’s and Con’s Advantages Disadvantages Simple Portable Maintainable
very wordy
has a very rigid format
not designed to handle scientific applications

6. Distinct features The language is simple No pointers
No user defined types
No user defined functions
‘Structure like’ data types
File records are also described with great detail, as are lines to be output to a printer
COBOL is self documenting

7. COBOL program layout
The layout, or format, or a COBOL program follows certain simple rules, which originated long ago when programs were punched onto 80-column punch cards.
COBOL programs are written in coding sheets. There are 80 columns in a line of the coding sheet.

8. COBOL program layout (continued)
Column Field
1-3 Page Number
4-6 Line Number (1-6 Sequence Number)
7 Continuation / Comment
A – Margin / Area A
B- Margin /Area B
Identification

9. Structure of COBOL Program
COBOL programs are hierarchical in structure.
Each element of the hierarchy consists of one or more subordinate elements.
The levels of hierarchy are Divisions, Sections, Paragraphs, Sentences and Statements
There are 4 main divisions and each division provides an essential part of the information required by the complier

10. Structure of COBOL Program (continued)
At the top of the COBOL hierarchy are the four divisions.
The sequence in which they are specified is fixed, and must follow the order:
IDENTIFICATION DIVISION. This division’s primary purpose is to name the program
ENVIRONMENT DIVISION. This division is primarily used to tell the computer about the input and output devices such files or printers.
DATA DIVISION provides descriptions of the data-items/fields processed by the program.
PROCEDURE DIVISION contains the code used to manipulate the data described in the DATA DIVISION. It is here that the programmer describes his algorithm.
Note:
Some COBOL compilers require that all the divisions be present in a program while others only require the IDENTIFICATION DIVISION and the PROCEDURE DIVISION

11. Hello World Example 000100 IDENTIFICATION DIVISION.
PROGRAM-ID. HELLOWORLD.
000300
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SOURCE-COMPUTER. RM-COBOL.
OBJECT-COMPUTER. RM-COBOL.
000800
DATA DIVISION.
FILE SECTION.
001100
PROCEDURE DIVISION.
101300
MAIN-LOGIC SECTION.
DISPLAY "Hello world!"
STOP RUN.

12. Character Set
There are 50 different characters in COBOL character set.
0-9 (10 numerals)
A-Z (26 English alphabets-only
capital letters)
– (minus sign or hyphen)
+ (Plus sign)
* (Asterisk)
/ (Slash)
= (Equal sign)
$ (Currency sign)
, (Comma)
; (Semi colon)
. (Period or decimal point)
“ (Quotation mark)
( (Left Parenthesis )
) (Right Parenthesis)
> (Greater than symbol)
< (Less than symbol)

13. Character Set (continued)
The characters 0-9 are called numeric characters or digits.
The characters A-Z are called letters
The remaining characters are called special characters.
The space or blank character in certain cases is treated as a letter.

14. COBOL WORDS There are 2 types of words in COBOL: 1.) Reserved word
A COBOL word can be formed using the following characters:
0-9
A-Z (a-z)
- (hyphen)
There are 2 types of words in COBOL:
1.) Reserved word
2.) User-defined word

15. COBOL WORDS (continued)
Paragraph names, Identifiers, File names can be defined by users.
The following rules must be adhered in forming COBOL user-defined words:
1.) A word cannot begin or end with a hyphen.
2.) A word can have at the maximum 30 characters.
3.) One of the characters must be a letter.
(Some compilers put the additional restrictions that the
first character must be a letter.)
4.) Except hyphen (-) no special character allowed.
5.) Cannot be a COBOL reserved word.

16. COBOL WORDS (continued)
Examples
Valid Word Invalid Word Reason
emp-sal -pay (it starts with a hyphen)
NET-SAL TOTAL MARK (blank space embedded)
N100 COMPUTE (Reserved word)
23 (No letter)

17. Literals
The actual values can also appear in a program. Such values are known as literals.
A data name may have different values at different points of time whereas a literal means the specific value which remains unchanged throughout the execution of the program.
For this reason a literal is often called a constant. Moreover the literal is not given a name; it represents itself and does not require to be defined in the DATA DIVISION.

18. Literals (continued) There are 3 types of literals:
Numeric. Formed by digits only. It can have a sign (+ or -) and can have a decimal point also.
b) Nonnumeric. Use in general to output messages or
headings. Characters that are enclosed between “ “
constitute nonnumeric literal.
c) Figurative Constants. Have some fixed names and
the compiler recognizes these names and it sets up
corresponding values in the object program.

19. Literals (continued) Figurative Constant Meaning ZERO ZEROS ZEROES
value 0
SPACE
SPACES
One or more blanks
HIGH-VALUE
HIGH-VALUES
Highest value in the
Collating sequence
LOW-VALUE
LOW-VALUES
Lowest value in the
QUOTE
QUOTES
one or more of “
ALL literal
one or more of the string characters comprising the literal

20. Summary Brief history or COBOL Underlining Philosophy of COBOL
Distinct Features of COBOL
COBOL Program Layout
Structure of COBOL program
Character Set
COBOL Words
Literals Summary of the chapter or topic