Explaining needed C recursion

Question

I need some help with this particular code. I do not really understand it to its fullest. Could someone take the time and explain it to me? What it does is take a word and p

Answer 1

NOTE Your example is at bottom, first your title question: Explaining needed C recursion

Recursion is a programming technique allowing operations to call themselves.
A simple (but meaningless) example would be:

void call(void);
int main(void)
{
    call();
}

void call(void)
{
    call(); 
}   

Note: This would simply go until the stack determines too many calls have stacked up, and crash the program.

A more meaningful example (for illustration) would be to write a palindrome character series (A - Z):

void Palindrome(char a)
{
    char b[2];
    sprintf(b, "%c", a);
    printf(b);
    if((a >= 65)&&(a < 90))
    {
        Palindrome(a+1);
    }
    sprintf(b, "%c", a);
    printf(b);
}  

This last example actually does two important things the first example did not do:
1) has a controlled exit criteria if((a >= 65)&&(a <= 90))
2) uses the results of prior calls with subsequent calls.

In your example: The reason the program works is that each time the operation calls itself, it is nesting deeper (one nest for each call) into the section: (this is true for all recursive programs)

  {
    reverse();
  }  

Similar in concept to:

{
    //do something
    {
        //do something
        {
            //do something
            //... and so on for as many recursions are necessary to meet exit criteria
        }
    }
}

"...but then how does it print out the reversed word?"
Only after the recursion reaches the programmed limit does execution flow down past the closing } and hit the next section, where it continues to unwind itself, each time accessing, in reverse order of stack, the values of c until each nested level has been unwound:

     }  //after exit criteria is met, execution flow goes from here....
     printf("%c", c); //prints values of c in reverse order.
 } //to here until number of recursions is exhausted.

at that time, if you step through using a debugger, you will see flow going from the upper } to the lower } executing printf() each time.