recursion and stack----help banfa

[jerico]

Hi.I know that recursion uses stack and a recursive function call itself until a terminating condition is satisfied.But i get problem in visualizing them..for example how the following program is executing...

void fun(int);
int main()
{
int a=3;
fun(a);
return 0;
}
void fun(int a)
{
if(a>0)
{
fun(--a);
printf("%d",a);
fun(--a);
}
}

the program outputs 0 1 2 0.thanks for any help.

jerico

[Banfa]

Well follow it through on paper listing the function calls that each function makes and parameter values or specificaly the value of a at each call, indenting for call depth (Note DC = Don't Care)

main(DC)
   fun(a = 3)
      fun(a = 2)
         fun(a = 1)
            fun(a = 0)
            printf(a = 0)
            fun(a = -1)
         printf(a = 1)
         fun(0)
      printf(a = 2)
      fun(1)
         fun(a = 0)
         printf(a = 0)
         fun(a = -1)