面试题与答案

Errors in COBOL programs are often handled using the ON EXCEPTION clause or the use of condition names. This allows for the graceful handling of errors.

Example:

READ FILE-1 INTO WS-RECORD ON EXCEPTION
  DISPLAY 'Error reading file'
END-READ.

The REDEFINES clause in COBOL is used to share storage between two or more data items. It allows multiple data descriptions for the same physical storage.

Example:

01 EMPLOYEE-NAME PIC X(20).
01 EMPLOYEE-NAME-REDEFINED REDEFINES EMPLOYEE-NAME PIC 9(9).

The MERGE statement in COBOL is used to merge two or more sorted input files into a single sorted output file. It is often used for sorting and merging files.

Example:

MERGE FILE-1, FILE-2 INTO SORTED-FILE.

The REWRITE statement in COBOL is used to modify the contents of a record in a file. It is typically used in conjunction with the READ statement to update existing records.

Example:

READ FILE-1 INTO DATA-RECORD.
REWRITE DATA-RECORD.

The EXIT PROGRAM statement in COBOL is used to terminate the entire program. It is often used in conjunction with a condition or as part of an error-handling routine.

Example:

IF ERROR-FLAG = 'Y' THEN
  EXIT PROGRAM.
END-IF.

The RESERVE statement in COBOL is used to allocate storage space for large data items. It ensures that sufficient memory is reserved to accommodate the specified data.

Example:

01 LARGE-DATA PIC X(1000).
RESERVE 1000 CHARACTERS FOR LARGE-DATA.

The SET ENVIRONMENT statement in COBOL is used to specify or change environment settings, such as the currency symbol, decimal point character, or date format.

Example:

SET ENVIRONMENT CURRENCY-SYMBOL '$'.

The REJECT statement in COBOL is used to return a record to an input file after it has been read. It is often used in conjunction with the REWRITE statement.

Example:

READ INPUT-FILE INTO DATA-RECORD.
IF CONDITION
  REJECT DATA-RECORD.
END-IF.

The ALTER statement in COBOL is used to modify the properties of data items at runtime. It allows dynamic changes to the length, picture, or usage of data items.

Example:

ALTER ITEM-DESCR TO PIC X(30).

The GENERATE statement in COBOL is used to dynamically create new paragraphs or sections during program execution. It enhances the flexibility and adaptability of the program.

Example:

GENERATE 'NEW-PARAGRAPH'.