help with a recursiv programm

Okay guys this is a subject that is a bit confusing to me... so just take it easy ...

Write a recursive function power(base, exponent) that when invoked returns
base ,exponent
for example, power(3,4 )= 3*3*3*3.Assume that exponent is an integer greater than or equal to 1.And the termination condition occurs when exponent is equal to 1 because base 1 = base..

Code:

#include <stdio.h>
#include <math.h>

int exponent ( int ,int ); //fucntion protoype

int main()
{
    int cnt, result;
    result = exponent (cnt, result );
    for ( cnt =2; cnt <= 10; cnt++ ){
        printf ("%d! = %d\n", cnt , result );
                   }


      system("PAUSE");
      return 0;
}

int exponent ( int a, int b )
{

 if ( a <= 1 )
 return 1;
 else
     return pow( (a*a),2);
   }

Something like

Code:

int exponent ( int a, int b )
{
  if ( b <= 1 )
    return 1;
  else
     return a * exponent(a,b-1);
}

When b=0...exponent(a,b) is still 1
so my codes

int exponent(int a,int b)
{
return b?a*exponent(a,b-1):1;
}

When b=0...exponent(a,b) is still 1
so my codes

int exponent(int a,int b)
{
return b?a*exponent(a,b-1):1;
}

Which requires one more function call than Salem's version. While this may not seem like a lot, if this is a function that were used many times, you would end up with unneeded overhead.

Quzah.

Originally posted by Salem
Something like

Code:

int exponent ( int a, int b )
{
  if ( b <= 1 )
    return 1;
  else
     return a * exponent(a,b-1);
}

shouldnt you return a when b==1 rather than 1

> shouldnt you return a when b==1 rather than 1

But I just copy/pasted the original author's code and made it recursive. Making it produce the right answer is an easy exercise for the reader

Originally posted by Salem
int exponent ( int a, int b )
{
if ( b <= 1 )
return 1;
else
return a * exponent(a,b-1);
}

Be careful this code should be changed to

Code:

{
    if (b==1)
      return a; // ****not return 1
    else
      return a*exponent(a,b-1);
}

You can return 1, if you check if (b==0).
Is that right?
But if I do it my own way, I will never use recursive programming for this case.