FORTRAN computed GO TO: Given JCOKE = 3; JCOKE = JCOKE + 1; GO TO (5, 8, 9, 11, 15, 16, 18, 20) JCOKE. To which statement label is control transferred?

Introduction / Context:Classical FORTRAN provides a computed GO TO statement for multi-way branching: GO TO (L1, L2, …, Ln) k transfers control to the k-th label in the list. Understanding the indexing behavior is essential for reading legacy scientific code.

Given Data / Assumptions:

• Initial JCOKE = 3.
• JCOKE is incremented by 1 before the computed GO TO.
• Label list is (5, 8, 9, 11, 15, 16, 18, 20) in that order.
• Indexing is 1-based (k = 1 selects the first label).

Concept / Approach:

Evaluate JCOKE after the increment, then index into the label list. Out-of-range indices typically fall through (implementation dependent), but here the index is within the valid range 1..8.

Step-by-Step Solution:

Verification / Alternative check:

Trace as if it were an array: labels[4] = 11. This matches standard FORTRAN behavior.

Why Other Options Are Wrong:

• 8 and 9: Correspond to indices 2 and 3, not 4.
• 16 and 20: Correspond to indices 6 and 8, respectively.

Common Pitfalls:

Assuming zero-based indexing; forgetting the prior increment of JCOKE; miscounting label positions.

Final Answer:

11