COBOL 튜토리얼

1. What is COBOL?

COBOL stands for Common Business-Oriented Language. It is a high-level programming language primarily used for business, finance, and administrative systems.

2. Why COBOL?

COBOL is often used for its readability and understandability, especially for non-programmers. It is commonly found in legacy systems, particularly in industries such as finance and government.

3. Installation Steps

1. Download COBOL compiler from the vendor's website.
2. Run the installer and follow the on-screen instructions.
3. Set up environment variables if necessary.

4. Setting Up COBOL Environment

To set up the COBOL environment, you need to configure the compiler and ensure that the necessary libraries are accessible.

      
SET COBOL_HOME=C:\path\to\cobol
SET PATH=%PATH%;%COBOL_HOME%\bin
      
    

5. Compiling and Running a COBOL Program

Once the environment is set up, you can compile and run COBOL programs using the command-line interface.

      
cobc -x -o program.exe program.cbl
./program.exe
      
    

1. What is COBOL?

COBOL, which stands for Common Business-Oriented Language, is a high-level programming language primarily used for business, finance, and administrative systems.

2. Features of COBOL

COBOL was designed to be easily readable and understandable by non-programmers, with syntax that resembles natural language, particularly English.

3. Why COBOL?

COBOL is commonly found in legacy systems, especially in industries such as finance, insurance, and government, where stability and reliability are crucial.

4. Example of COBOL Code

Below is a simple example of a COBOL program:

      
IDENTIFICATION DIVISION.
PROGRAM-ID. HelloWorld.
PROCEDURE DIVISION.
DISPLAY 'Hello, World!'.
STOP RUN.
      
    

1. What is the syntax of COBOL?

COBOL syntax is designed to be readable and resembles natural language, particularly English. Statements are written in a structured format with specific divisions and sections.

2. Structure of COBOL Program

A COBOL program consists of various divisions, sections, paragraphs, and sentences. The main divisions are:

• Identification Division
• Environment Division
• Data Division
• Procedure Division

3. Example of COBOL Code

Below is an example of a simple COBOL program:

      
IDENTIFICATION DIVISION.
PROGRAM-ID. HelloWorld.
PROCEDURE DIVISION.
DISPLAY 'Hello, World!'.
STOP RUN.
      
    

1. What are the data types in COBOL?

COBOL supports various data types for representing different kinds of information. Some common data types include:

• Numeric: INTEGER, FLOAT, PACKED-DECIMAL
• Alphanumeric: STRING, CHAR
• Boolean: BOOLEAN
• Date and Time: DATE, TIME

2. Example of Data Declarations in COBOL

Below is an example of data declarations in COBOL:

      
DATA DIVISION.
WORKING-STORAGE SECTION.
01 EMPLOYEE-ID PIC X(5).
01 EMPLOYEE-NAME PIC X(30).
01 EMPLOYEE-SALARY PIC 9(7)V99.
01 IS-EMPLOYEE-ACTIVE PIC X.
01 EMPLOYEE-HIRE-DATE PIC 9(6).
      
    

1. What is file handling in COBOL?

File handling in COBOL involves reading from and writing to external files. COBOL provides various file organization modes and access modes to handle different types of files.

2. File Organizations and Access Modes

COBOL supports different file organizations such as sequential, indexed, and relative, and access modes such as sequential, random, and dynamic.

3. Example of File Handling in COBOL

Below is an example of file handling in COBOL:

      
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT EMPLOYEE-FILE ASSIGN TO 'employee.dat'
       ORGANIZATION IS SEQUENTIAL.

DATA DIVISION.
FILE SECTION.
FD EMPLOYEE-FILE.
01 EMPLOYEE-RECORD.
  05 EMPLOYEE-ID PIC X(5).
  05 EMPLOYEE-NAME PIC X(30).
  05 EMPLOYEE-SALARY PIC 9(7)V99.

PROCEDURE DIVISION.
OPEN INPUT EMPLOYEE-FILE.
READ EMPLOYEE-FILE INTO EMPLOYEE-RECORD.
DISPLAY 'Employee ID: ' EMPLOYEE-ID.
DISPLAY 'Employee Name: ' EMPLOYEE-NAME.
DISPLAY 'Employee Salary: ' EMPLOYEE-SALARY.
CLOSE EMPLOYEE-FILE.
      
    

1. What are conditional statements in COBOL?

Conditional statements in COBOL allow you to execute different sets of instructions based on certain conditions. COBOL supports various conditional statements such as IF, ELSE, and EVALUATE.

2. Example of IF Statement in COBOL

Below is an example of an IF statement in COBOL:

      
IF EMPLOYEE-SALARY > 50000
    DISPLAY 'High Salary'
ELSE
    DISPLAY 'Low Salary'
END-IF.
      
    

3. Example of EVALUATE Statement in COBOL

Below is an example of an EVALUATE statement in COBOL:

      
EVALUATE EMPLOYEE-DEPARTMENT
    WHEN 'IT'
DISPLAY 'Information Technology'
    WHEN 'HR'
DISPLAY 'Human Resources'
    WHEN 'SALES'
DISPLAY 'Sales'
    WHEN OTHER
DISPLAY 'Other Department'
END-EVALUATE.
      
    

1. What are loops in COBOL?

Loops in COBOL allow you to execute a set of instructions repeatedly until a certain condition is met. COBOL supports various types of loops such as PERFORM, PERFORM UNTIL, and PERFORM VARYING.

2. Example of PERFORM Loop in COBOL

Below is an example of a PERFORM loop in COBOL:

      
PERFORM 10-TIMES
    DISPLAY 'Hello, World!'
END-PERFORM.

10-TIMES.
DISPLAY 'Loop iteration'.
      
    

3. Example of PERFORM UNTIL Loop in COBOL

Below is an example of a PERFORM UNTIL loop in COBOL:

      
PERFORM UNTIL EMPLOYEE-COUNT = 10
    ADD 1 TO EMPLOYEE-COUNT
    DISPLAY 'Employee Count: ' EMPLOYEE-COUNT
END-PERFORM.
      
    

1. What are subroutines and functions in COBOL?

Subroutines and functions in COBOL allow you to modularize your code by grouping related instructions into separate sections that can be called from other parts of the program. This promotes code reusability and maintainability.

2. Example of Subroutine in COBOL

Below is an example of a subroutine in COBOL:

      
IDENTIFICATION DIVISION.
PROGRAM-ID. MainProgram.

DATA DIVISION.
WORKING-STORAGE SECTION.
01 NUM1 PIC 9(3) VALUE 100.
01 NUM2 PIC 9(3) VALUE 200.
01 RESULT PIC 9(4).

PROCEDURE DIVISION.
CALL 'AddNumbers' USING NUM1, NUM2, RESULT.
DISPLAY 'Result: ' RESULT.
STOP RUN.

IDENTIFICATION DIVISION.
PROGRAM-ID. AddNumbers.

DATA DIVISION.
LINKAGE SECTION.
01 A PIC 9(3).
01 B PIC 9(3).
01 C PIC 9(4).

PROCEDURE DIVISION USING A B C.
COMPUTE C = A + B.
EXIT PROGRAM.
      
    

1. What are arrays in COBOL?

Arrays in COBOL allow you to store multiple values of the same data type under a single name. They provide a way to efficiently manage and manipulate collections of data elements.

2. Example of Array Declaration in COBOL

Below is an example of an array declaration in COBOL:

      
DATA DIVISION.
WORKING-STORAGE SECTION.
01 NUMBERS OCCURS 5 TIMES PIC 9(3) VALUE ZERO.
01 NAMES OCCURS 3 TIMES PIC X(20).
      
    

3. Example of Array Usage in COBOL

Below is an example of how to use an array in COBOL:

      
MOVE 100 TO NUMBERS(1).
MOVE 200 TO NUMBERS(2).
MOVE 'John' TO NAMES(1).
MOVE 'Doe' TO NAMES(2).
      
    

1. What is string handling in COBOL?

String handling in COBOL involves manipulating character strings, such as concatenation, comparison, and extraction of substrings. COBOL provides various string manipulation functions and operators to perform these tasks.

2. Example of String Manipulation in COBOL

Below is an example of string manipulation in COBOL:

      
MOVE 'Hello' TO STRING1.
MOVE 'World' TO STRING2.
STRING STRING1 ' ' STRING2 DELIMITED BY SIZE INTO RESULT.
DISPLAY 'Concatenated String: ' RESULT.
      
    

1. What is sorting and searching in COBOL?

Sorting and searching in COBOL involve arranging data in a specified order and finding particular elements within a dataset. COBOL provides built-in functions and procedures for performing sorting and searching operations efficiently.

2. Example of Sorting in COBOL

Below is an example of sorting an array in COBOL:

      
DATA DIVISION.
WORKING-STORAGE SECTION.
01 NUMBERS OCCURS 5 TIMES PIC 9(3) VALUE ZERO.

PROCEDURE DIVISION.
MOVE 100 TO NUMBERS(1).
MOVE 80 TO NUMBERS(2).
MOVE 120 TO NUMBERS(3).
MOVE 90 TO NUMBERS(4).
MOVE 110 TO NUMBERS(5).

PERFORM VARYING I FROM 1 BY 1 UNTIL I > 4
    PERFORM VARYING J FROM I + 1 BY 1 UNTIL J > 5
IF NUMBERS(I) > NUMBERS(J)
    MOVE NUMBERS(I) TO TEMP
    MOVE NUMBERS(J) TO NUMBERS(I)
    MOVE TEMP TO NUMBERS(J)
END-IF
    END-PERFORM
END-PERFORM.
      
    

3. Example of Searching in COBOL

Below is an example of searching for an element in an array in COBOL:

      
DATA DIVISION.
WORKING-STORAGE SECTION.
01 NUMBERS OCCURS 5 TIMES PIC 9(3) VALUE ZERO.
01 SEARCH-NUMBER PIC 9(3) VALUE 120.
01 FOUND PIC X VALUE 'N'.

PROCEDURE DIVISION.
MOVE 100 TO NUMBERS(1).
MOVE 80 TO NUMBERS(2).
MOVE 120 TO NUMBERS(3).
MOVE 90 TO NUMBERS(4).
MOVE 110 TO NUMBERS(5).

PERFORM VARYING I FROM 1 BY 1 UNTIL I > 5
    IF NUMBERS(I) = SEARCH-NUMBER
MOVE 'Y' TO FOUND
EXIT PERFORM
    END-IF
END-PERFORM.

IF FOUND = 'Y'
    DISPLAY 'Number found.'
ELSE
    DISPLAY 'Number not found.'
END-IF.
      
    

1. How does error handling work in COBOL?

COBOL provides various mechanisms for error handling, including error codes, exception handling, and error reporting. Programmers can use these features to detect and handle errors gracefully during program execution.

2. Example of Error Handling in COBOL

Below is an example of error handling in COBOL:

      
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT EMPLOYEE-FILE ASSIGN TO 'employee.dat'
       ORGANIZATION IS SEQUENTIAL.

DATA DIVISION.
FILE SECTION.
FD EMPLOYEE-FILE.
01 EMPLOYEE-RECORD.
  05 EMPLOYEE-ID PIC X(5).
  05 EMPLOYEE-NAME PIC X(30).
  05 EMPLOYEE-SALARY PIC 9(7)V99.

PROCEDURE DIVISION.
TRY.
    OPEN INPUT EMPLOYEE-FILE.
    READ EMPLOYEE-FILE INTO EMPLOYEE-RECORD
AT END
    DISPLAY 'No more records.'
    END-READ.
CATCH file-status-error
    DISPLAY 'Error reading file: ' FILE-STATUS.
END-TRY.
      
    

1. What are debugging techniques in COBOL?

Debugging techniques in COBOL involve identifying and fixing errors or bugs in the program. Some common debugging techniques include using display statements for tracing, using debugging tools provided by COBOL compilers, and analyzing program logic and data flow.

2. Example of Debugging Technique in COBOL

Below is an example of using display statements for tracing in COBOL:

      
IDENTIFICATION DIVISION.
PROGRAM-ID. DebugExample.

DATA DIVISION.
WORKING-STORAGE SECTION.
01 NUM1 PIC 9(3) VALUE 100.
01 NUM2 PIC 9(3) VALUE 200.
01 RESULT PIC 9(4).

PROCEDURE DIVISION.
DISPLAY 'Debugging started...'.
COMPUTE RESULT = NUM1 + NUM2.
DISPLAY 'Result: ' RESULT.
DISPLAY 'Debugging ended.'.
STOP RUN.