GATE CS 2019 Q18 — Programming in C

To find the value printed by the program, let us trace the execution step-by-step:

1. Initialization in main()

Initially, we have:
x = 2, y = 5

2. First Function Call: y = jumble(y, x);

• The actual arguments passed to jumble are y (which is $5$) and x (which is $2$).
• Inside jumble(int x, int y):
  • The formal parameter x receives the value $5$.
  • The formal parameter y receives the value $2$.
• The statement x = 2 * x + y; is executed: $$x = 2 \times 5 + 2 = 12$$
• The function returns x (which is $12$).
• In main(), this returned value is assigned to y.

At this point, the variables in main() are:
x = 2, y = 12

3. Second Function Call: x = jumble(y, x);

• The actual arguments passed to jumble are y (which is $12$) and x (which is $2$).
• Inside jumble(int x, int y):
  • The formal parameter x receives the value $12$.
  • The formal parameter y receives the value $2$.
• The statement x = 2 * x + y; is executed: $$x = 2 \times 12 + 2 = 26$$
• The function returns x (which is $26$).
• In main(), this returned value is assigned to x.

At this point, the variables in main() are:
x = 26, y = 12

4. Output

The statement printf("%d \n", x); prints the value of x, which is 26.