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HARSFEN0602
Example:
function factorial() ; **Function prototype
…
IA[1]=3
IA[2]=1
factorial() **Function call
BG
…
function factorial() **Function for factorial
global int IA[] ; **Definition of array as global inside function
IA[2]=IA[2]*IA[1] **Recursive algorithm
IA[1]=IA[1]-1
if ( IA[1] > 1 ) factorial() ; end **Recursive call
return **Function end
The factorial function of the example calculates the factorial of 3 in IA[2]. The variable IA[1] counts how
many times the function factorial is executed.
The program executes as follows:
Code IA[1] IA[2] Call stack
IA[1]=3 3 Undefined Empty
IA[2]=1 Unchanged 1 Empty
factorial Unchanged Unchanged
BG
IA[2]=IA[2]*IA[1] Unchanged 3 Unchanged
IA[1]=IA[1]-1 2 Unchanged Unchanged
if ( IA[1] > 1 ) factorial() ; end Unchanged Unchanged
RT
BG
IA[2]=IA[2]*IA[1] Unchanged 6 Unchanged
IA[1]=IA[1]-1 1 Unchanged Unchanged
if ( IA[1] > 1 ) factorial() ; end Unchanged Unchanged Unchanged (condition is
false)
return
Unchanged Unchanged
BG (Program jumps to
the return which was on
top the call stack)
return
Unchanged Unchanged Empty (Program jumps to
the BG which was on top
the call stack)
BG Unchanged Unchanged Unchanged