Sunday 12 March 2023

COBOL Interview Questions and Answers | Frequently asked COBOL interview questions.

COBOL interview questions and answers
Frequently asked COBOL interview questions.


COBOL (Common Business Oriented Language) is a programming language that was developed in the late 1950s for business and financial applications. Despite being an older programming language, it is still widely used in the banking, insurance, and government sectors. 

As a result, many companies require COBOL programmers and developers for their projects, and this has led to an increase in COBOL-related job opportunities. If you're planning to apply for a job that requires COBOL skills, it's essential to prepare well for the interview. 

In this blog post, we will discuss the most common COBOL interview questions and answers, as well as some advanced and frequently asked questions. We will also provide some tips on how to prepare for a COBOL programming interview. So, whether you're an experienced COBOL developer or a fresher, read on to know more about the top COBOL interview questions for job interviews in the mainframe development industry. So, let's get started with our top COBOL Interview Questions. 

The most common COBOL interview questions.

Q: What are the different types of COBOL files?
A: There are three types of COBOL files: sequential, indexed, and relative.

Q: How do you define a file in COBOL?
A: To define a file in COBOL, we use the FILE-CONTROL paragraph and the SELECT statement. The SELECT statement specifies the file name, access mode, and file organization.

Q: What are the sections required for opening a file in COBOL?
A: The sections required for opening a file in COBOL are FILE-CONTROL, ENVIRONMENT, and DATA DIVISION.

Q: How do you read a file in COBOL?
A: To read a file in COBOL, we use the READ statement. The READ statement reads the next record in the file and moves the data into the record area.

Q. What is the difference between sequential and random access files?
A: Sequential access files are accessed in the order in which they were written, while random access files can be accessed in any order.

Q: What are the various file processing modes in COBOL?
A: The file processing modes in COBOL are INPUT, OUTPUT, I-O, and EXTEND.

Q: How do you write records to a file in COBOL?
A: We use the WRITE statement to write records to a file in COBOL. The WRITE statement writes the data in the recording area to the file.

Q: What is a VSAM file and how is it different from a sequential file?
A: A VSAM file is a file that is organized using the Virtual Storage Access Method. It is different from a sequential file in that it supports random access and can be read and written in any order.

Q: How do you handle errors while reading or writing to a file in COBOL?
A: To handle errors while reading or writing to a file in COBOL, we use the FILE STATUS clause. The FILE STATUS clause returns a status code that indicates the success or failure of the file operation.

Advanced COBOL interview questions.


Q: How do you implement file locking in COBOL programs?
A: To implement file locking in COBOL programs, we use the LOCK MODE clause in the SELECT statement. The LOCK MODE clause specifies the type of locking to be used for the file. For example, LOCK MODE IS EXCLUSIVE will lock the file exclusively, preventing other programs from accessing it.

Q: What is a record layout in COBOL, and how is it defined?
A: A record layout in COBOL defines the structure and layout of a record in a file. It is defined using the FD (File Description) and 01 (Level Number) statements in the Data Division.

Q: How do you update a record in a file using COBOL?
A: To update a record in a file using COBOL, we use the UPDATE statement. The UPDATE statement updates the current record in the file with the data in the record area.

Q: What is a file status code, and how is it used in COBOL file handling?
A: A file status code is a numeric code that indicates the status of a file operation. It is used in COBOL file handling to detect and handle errors and exceptions.

Q: How do you delete a record from a file using COBOL?
A: To delete a record from a file using COBOL, we use the DELETE statement. The DELETE statement removes the current record from the file.

Q: What is a file organization in COBOL, and what are the different types?
A: A file organization in COBOL refers to the way data is stored in a file. The different types of file organization are sequential, indexed, and relative.

Q: What is the purpose of the ACCESS MODE clause in a COBOL SELECT statement?
A: The ACCESS MODE clause in a COBOL SELECT statement specifies the type of access to be used for the file. The different types are SEQUENTIAL, RANDOM, DYNAMIC, and EXTEND.

Q: How do you handle end-of-file conditions in COBOL file handling?
A: To handle end-of-file conditions in COBOL file handling, we use the END-OF-FILE phrase on the READ statement. This phrase is executed when there are no more records to be read from the file.

Q: What is the difference between a physical and a logical record in COBOL?
A: A physical record in COBOL is the actual record stored on disk, while a logical record is a record as it is represented in the program.

Q: How do you handle duplicate keys in an indexed file in COBOL?
A: To handle duplicate keys in an indexed file in COBOL, we use the DUPLICATES clause in the SELECT statement. This clause specifies how duplicate keys should be handled, such as by ignoring them or storing them in a separate file.

Q: What is the purpose of the FILE STATUS clause in COBOL file handling?
A: The FILE STATUS clause in COBOL file handling returns a status code that indicates the success or failure of a file operation. It is used to detect and handle errors and exceptions.

Q: What is a VSAM file in COBOL, and how is it different from a standard sequential file?
A: A VSAM file in COBOL is a type of file that is used for high-performance data access. It is different from a standard sequential file because it allows for direct access to records using a key.

Q: How do you handle record locking in COBOL file handling?
A: To handle record locking in COBOL file handling, we use the LOCK and UNLOCK statements. The LOCK statement locks a record in the file, preventing other programs from accessing it, while the UNLOCK statement releases the lock.

Q: What is a relative record number in COBOL file handling, and how is it used?
A: A relative record number in COBOL file handling is a unique identifier that is assigned to each record in a relative file. It is used to access records directly using the RBA (Relative Byte Address) of the record.

Q: What is the difference between an OPEN INPUT and OPEN OUTPUT statement in COBOL file handling?
A: An OPEN INPUT statement in COBOL file handling opens a file for reading, while an OPEN OUTPUT statement opens a file for writing.

Q: How do you handle file sharing in COBOL file handling?
A: To handle file sharing in COBOL file handling, we use the SHARE OPTIONS clause in the SELECT statement. This clause specifies how the file should be shared among different programs.

Q: What is a blocking factor in COBOL file handling, and how is it used?
A: A blocking factor in COBOL file handling is the number of records that are read or written at one time. It is used to optimize file access by reducing the number of I/O operations.

Q: How do you handle errors and exceptions in COBOL file handling?
A: To handle errors and exceptions in COBOL file handling, we use the FILE STATUS clause and the various file status codes. We also use the INVALID KEY and AT END phrases on the READ statement to handle specific errors.

Q: What is the difference between a fixed-length record and a variable-length record in COBOL?
A: A fixed-length record in COBOL file handling has a set length, while a variable-length record can have a different length for each record. Variable-length records are often used for text files.

Q: What is a relative file in COBOL, and how is it different from an indexed file?
A: A relative file in COBOL is a type of file that is organized based on the record's position within the file. It is different from an indexed file because it does not use keys to access records.

Q: What is the purpose of the REWRITE statement in COBOL file handling?
A: The REWRITE statement in COBOL file handling updates the current record in the file with the data in the record area. It is used to modify an existing record without deleting and re-adding it to the file.

How to prepare for a COBOL programming interview?

Preparing for a COBOL programming interview can be daunting, especially if you are new to the language or haven't used it in a while. Here are some tips to help you prepare for your COBOL interview:
  • Refresh your COBOL knowledge: Review the basics of COBOL, including syntax, structure, and data types. You should also practice coding exercises to ensure you're comfortable with the language's logic and syntax.
  • Research the company: Before your interview, research the company and the job requirements thoroughly. Learn about the company's business and the specific COBOL projects they are working on.
  • Familiarize yourself with COBOL tools: Become familiar with COBOL development tools such as debugging, profiling, and performance analysis tools.
  • Prepare for technical questions: Expect to be asked technical questions related to COBOL programming. Some common topics include working with file systems, data types, and arithmetic operations.
  • Practice with mock interviews: Practice mock interviews with friends or family members to get a feel for answering COBOL interview questions. You can also look for online mock interviews or coaching services to help you prepare.

By following these tips, you can boost your confidence and ensure that you are fully prepared to tackle any COBOL interview questions that come your way. Remember to showcase your passion for programming and your experience in the mainframe development industry to stand out as a top candidate for the job.

Conclusion. 

In summary, if you are planning to apply for a job that requires COBOL programming skills, it's crucial to prepare well for the interview. In this blog post, we have covered the most common COBOL interview questions and answers, as well as some advanced and frequently asked questions. 

We have also provided some tips on how to prepare for a COBOL programming interview, including how to answer basic and advanced questions. By reviewing this post, you will be better equipped to impress your potential employer with your COBOL knowledge, whether you are an experienced developer or a fresher. 

Remember to practice your responses to these common COBOL interview questions and demonstrate your passion and experience for programming languages, especially COBOL, during the interview. With the right preparation, you can ace your next COBOL job interview and land your dream job in the mainframe development industry.


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