GATE CS 1999 Q2.13 — Programming in C

In a programming language with dynamic scoping, a free variable in a procedure is resolved by searching the execution call stack (the dynamic chain) backward from the point of the call until a definition for that variable is found.

Let's trace the execution of the program step-by-step:

1. Global Initialization: The global variable x is declared. In the main block, x is assigned the value 0.25.
   Current active binding for x: $\text{Global } x = 0.25$.
2. First Call (show): The main block calls show.
   • Inside show, the variable x needs to be printed.
   • Looking back at the call stack: show $\leftarrow$ main.
   • The most recent active binding for x is the global x, which has the value 0.25.
3. Second Call (small): The main block calls small.
   • Inside small, a local variable x is declared and assigned the value 0.125.
   • Current active binding for x: $\text{Local } x \text{ of } \text{small} = 0.125$.
4. Nested Call (show from small): Inside small, the procedure show is called.
   • Inside show, we look up x.
   • Looking back at the call stack: show $\leftarrow$ small $\leftarrow$ main.
   • The most recent active binding for x in this chain is the local variable x inside small, which has the value 0.125.

Therefore, the output of the program is 0.25 0.125, which corresponds to Option C.