面试题与答案

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

The PERFORM statement is used for loop control in COBOL. It allows the repeated execution of a set of statements until a specified condition is met.

Example:

PERFORM 5 TIMES
  DISPLAY 'Hello, World!'
END-PERFORM.

The INITIALIZE verb is used to set the initial values for data items in COBOL. It initializes numeric items to zero and alphanumeric items to spaces.

Example:

01 COUNT PIC 9(3).
INITIALIZE COUNT.

The FILE SECTION in COBOL is used to describe the structure and attributes of files used by the program. It includes the FD (File Description) entries.

COBOL provides the COMPUTE statement for decimal arithmetic. It allows the programmer to perform arithmetic operations on numeric data items with explicit precision.

Example:

COMPUTE TOTAL = AMOUNT-1 + AMOUNT-2.

The LEVEL number in COBOL is used to indicate the hierarchy and nesting level of data items. It determines the structure and organization of data in the Data Division.

Example:

01 EMPLOYEE-RECORD.
  05 EMPLOYEE-ID PIC 9(5).
  05 EMPLOYEE-NAME PIC X(20).

Data movement in COBOL is achieved through the MOVE verb. It transfers the value of one data item to another, and it can handle various data types.

Example:

MOVE 100 TO AMOUNT.

COBOL supports file processing through file control entries in the File Section. The OPEN, READ, WRITE, and CLOSE statements are used for file operations.

Example:

OPEN INPUT FILE-1.
READ FILE-1 INTO DATA-RECORD.
CLOSE FILE-1.

The SET statement in COBOL is used to assign values to index names, condition names, and other special registers. It is essential for controlling program flow.

Example:

SET EMPLOYEE-INDEX TO 1.

The INITIALIZE verb in COBOL is used to set the initial values for data items. It initializes numeric items to zero and alphanumeric items to spaces.

Example:

01 COUNT PIC 9(3).
INITIALIZE COUNT.

The COPY statement in COBOL is used for including copybooks in the source code. It allows the reuse of common code and improves maintainability.

Example:

COPY 'COMMON-FILE'.

The ACCEPT statement in COBOL is used for interactive input. It allows the program to receive data directly from the user during runtime.

Example:

ACCEPT EMPLOYEE-NAME.

The WORKING-STORAGE section in COBOL is used to declare variables that retain their values throughout the execution of the program. It provides working storage for temporary data.

Example:

WORKING-STORAGE SECTION.
01 COUNTER PIC 9(3) VALUE 0.

The CALL statement in COBOL is used to invoke subprograms or procedures from other programs. It allows modular programming and code reuse.

Example:

CALL 'SUB-PROGRAM' USING PARAMETER-1 PARAMETER-2.

The END-IF statement in COBOL marks the end of an IF statement block. It is used to indicate the conclusion of the conditional code and resume normal program flow.

Example:

IF AMOUNT > LIMIT
  DISPLAY 'Amount exceeds limit'
END-IF.

The ACCEPT FROM statement in COBOL is used to receive data directly from an external device, such as a keyboard. It simplifies interactive input operations.

Example:

ACCEPT WS-EMPLOYEE-ID FROM 'Enter Employee ID:'.

The COMPUTATIONAL-3 (COMP-3) clause in COBOL is used to define packed-decimal data items. It represents decimal numbers in a packed format for efficient storage.

Example:

01 AMOUNT PIC 9(5) COMP-3.