How to Hire a Backend Developer (COBOL)

• a4 bytesCorrect
• b7 bytes
• c8 bytes
• d15 bytes

Explanation: For packed decimal (COMP-3), each digit occupies a nibble (4 bits), and the sign occupies the last nibble. Byte size = (Digits + 1) / 2 = (7 + 1) / 2 = 4 bytes.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aOCCURS ... DEPENDING ONCorrect
• bOCCURS ... INDEXED BY
• cOCCURS ... REDEFINES
• dOCCURS ... ASCENDING KEY

Explanation: The DEPENDING ON sub-clause of OCCURS sets a variable bound for a table, dynamically defining the current number of active elements based on an integer control variable.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aThe redefining field must have a level number lower than the field being redefined.
• bThe REDEFINES clause must immediately follow the data-name of the redefining entry.Correct
• cRedefinition can only take place between variables with identical PICTURE clauses.
• dREDEFINES must be written in the Procedure Division prior to any arithmetic statement.

Explanation: The REDEFINES clause must immediately follow the data-name of the defining variable (e.g. 05 NEW-VAR REDEFINES OLD-VAR), and both must have the same level number.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aEVALUATE checks multiple criteria in one structured statement without deep nesting.Correct
• bEVALUATE is restricted to checking single numeric flags, while IF is required for alphanumeric strings.
• cEVALUATE compiles into high-overhead loops, whereas IF processes statements asynchronously.
• dEVALUATE forbids a default WHEN OTHER clause, so every case must be matched explicitly.

Explanation: EVALUATE is COBOL's switch-case/multi-branch statement. It improves readability by replacing deep nested IF structures and supports checking multiple logical criteria efficiently.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aThe table must apply a REDEFINES clause over its backing storage area.
• bThe table must be sorted on a key declared ASCENDING or DESCENDING in OCCURS.Correct
• cThe index variable must be manually set to 1 using SET before executing.
• dThe table must be stored in the LINKAGE SECTION rather than WORKING-STORAGE.

Explanation: SEARCH ALL performs a binary search, which requires the table entries to be sorted and explicitly declared with ASCENDING or DESCENDING KEY. Basic SEARCH does a linear scan.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aIt copies all arguments into the subprogram's working-storage heap, creating isolated local clones.
• bIt maps the passed fields by reference to the caller's storage via the PROCEDURE DIVISION USING header.Correct
• cIt pulls the parameters from a global dynamic system register named SYS-ARGS at entry.
• dIt applies a REDEFINES clause to recast each passed parameter into a local datatype.

Explanation: By default, parameters in CALL ... USING are passed BY REFERENCE. The Linkage Section declares the structure, and the PROCEDURE DIVISION USING header binds them to the caller's memory buffers.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aThe file was successfully opened but contains zero records.
• bThe physical file referenced by the SELECT statement was not found.Correct
• cThe program has insufficient operating system permissions to read the file.
• dThe record length in the FD description does not match the physical file structure.

Explanation: File Status '35' represents 'File not found' when attempting to open a non-existent physical file in INPUT or I-O mode.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aCOMP-1 is single-precision float; COMP-2 is double-precision float; neither uses PIC.Correct
• bCOMP-1 is 2-byte integer; COMP-2 is 4-byte integer; both require PIC 9 structure.
• cCOMP-1 holds binary packed decimal while COMP-2 holds unpacked zoned decimal digits.
• dCOMP-1 is reserved for alphabetic flags; COMP-2 is reserved for database primary keys.

Explanation: COMP-1 specifies single-precision floating point (4 bytes), and COMP-2 specifies double-precision floating point (8 bytes). Unlike integers, floating-point variables do not use a PICTURE clause.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aWITH DUPLICATESCorrect
• bALLOW MULTIPLE
• cINDEXED BY MULTIPLES
• dREDUNDANT VALUES

Explanation: The WITH DUPLICATES clause must be specified on the ALTERNATE RECORD KEY definition in the SELECT statement if the alternate index can contain duplicate keys.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.

• aThe compiler refuses to generate an executable binary and reports a fatal scope error.
• bA trailing period implicitly closes all open blocks, so later statements can fall inside the conditional.Correct
• cEach nested branch is dispatched onto its own separate execution thread at runtime.
• dThe program will crash with an out-of-memory error when executing the nested branches.

Explanation: Without explicit scope terminators, a period (.) acts as the implicit terminator for all open blocks, which can lead to structural logic bugs by grouping unrelated statements into an IF block.

Why it matters: Evaluates practical understanding of COBOL core principles, execution model, and runtime characteristics in production.