When designing a modular COBOL application, you want to define a variable that will have scope across different programs but not be accessible from external applications. What approach would you choose?
- Declare the variable in the DATA DIVISION
- Use of copybooks
- Use of global variables
- Use of static variables
In COBOL, you can define a variable with scope across different programs by placing it in a copybook. Copybooks are reusable modules containing data definitions and are included in programs where the data is needed, ensuring data consistency and modularity while restricting access to external applications.
Your COBOL application is encountering performance issues when reading large amounts of data from a VSAM file. What optimization techniques can you apply to improve performance?
- Apply caching mechanisms to reduce disk I/O
- Implement parallel processing for data retrieval
- Increase buffer size in COBOL I/O statements
- Use indexed file organization for faster access
To improve performance when reading large amounts of data from a VSAM file, applying caching mechanisms to reduce disk I/O is effective. Caching stores frequently accessed data in memory, minimizing the need for repeated disk reads and enhancing overall application speed.
What is the purpose of the FUNCTION PRESENTATION intrinsic function in COBOL?
- It calculates the present value of an investment
- It converts a character string to a numeric value
- It retrieves the current presentation layer
- It returns the presentation of a numeric value as a character string
The FUNCTION PRESENTATION intrinsic function in COBOL is used to return the presentation of a numeric value as a character string, allowing for custom formatting.
What is parameter passing in subprograms, and why is it important?
- Parameter passing is a mechanism to pass data between programs and is important for sharing information
- Parameter passing is not supported in COBOL
- Parameter passing is only applicable to procedures, not functions
- Parameter passing refers to the allocation of storage for variables in a subprogram
Parameter passing in subprograms involves transferring data between the calling program and the called subprogram. It allows the subprogram to receive input values, process them, and potentially return results to the calling program. This mechanism enhances code modularity and facilitates code reuse.
In a COBOL "IF" statement, what happens if the condition is not met?
- An error is generated
- The "ELSE" statement is executed
- The control transfers to the next statement outside the "IF" block
- The program terminates abruptly
If the condition in a COBOL "IF" statement is not met, the control transfers to the next statement outside the "IF" block. If an "ELSE" statement is present, it will be executed; otherwise, the program continues with the next statement.
In COBOL, the _______ statement is used to perform a series of statements repeatedly.
- ITERATE
- LOOP
- PERFORM
- REPEAT
The PERFORM statement in COBOL is used to create loops, allowing a series of statements to be executed repeatedly. It provides various clauses for controlling the loop, such as UNTIL, WITH TEST BEFORE, and WITH TEST AFTER.
In the context of COBOL file handling, what is "read-ahead" and how does it contribute to performance improvement?
- It reads multiple records in advance to reduce I/O wait time
- It reads records from the end of the file first
- It reads records sequentially for faster processing
- It skips unnecessary records during reading
"Read-ahead" in COBOL involves reading multiple records in advance and buffering them in memory, reducing I/O wait time and enhancing performance by minimizing the need for repeated disk access.
How do you handle exceptions and errors in the COBOL Procedure Division?
- Employing the IGNORE statement
- Implementing the EXCEPTION condition
- Using the EXIT statement
- Utilizing the GOTO statement
Exceptions and errors in the COBOL Procedure Division are handled by implementing the EXCEPTION condition. It allows the programmer to define specific actions to be taken when certain exceptional conditions occur during program execution.
In a COBOL program, what is the primary use of the VARYING clause within a PERFORM loop?
- To control the flow of execution in nested loops
- To define variables with varying data types
- To execute the loop only if a condition is met
- To iterate over a range of values for a loop variable
The VARYING clause in a PERFORM loop is used to iterate over a range of values for a loop variable, allowing the repeated execution of a block of code with different values during each iteration.
In COBOL, what is the purpose of the ACCESS MODE clause when working with relative files?
- DYNAMIC
- KEY
- RANDOM
- SEQUENTIAL
The ACCESS MODE clause in COBOL specifies how records in a relative file are accessed. RANDOM allows direct access to records based on the record number. This is useful when individual records need to be retrieved without the need to read sequentially through the file.