Recursive Reversal Function

[rocketman]

I'm currently working on a code for taking in a character array, a[], and it's length n. It's then supposed to reverse all of the letters and return them as a string

string RevIt(char a[], int n)
{
	string ret, cur;
	if(n==0)
		return ret+=a[n];
	else
  	{
    	 ret+=RevIt(a,n-1);
		 cur=a[n];
		 return cur;
  	}
}

it's not throwing anything out, and i'd just like someone to give me advice/help with it. Thanks!

[ne555]

This is your code

string RevIt(char a[], int n){
  return string(a[n],1);
}

[rocketman]

how would i go about changing my code so that it reverses the entire char array into a string? I can only get it to return the first character at the moment

[Jikax]

#include <iostream>
#include <sstream>
using namespace std;

string RevIt(char a[], int n)
{
  stringstream stream;
  for(int i=(n-1);i>=0;i--)
    stream << a[i];
  return stream.str();
}

[rocketman]

While that does indeed work(I actually had it like that before), I need to make this function do it via recursion

[Jikax]

and recursive:

#include <iostream>
#include <sstream>
using namespace std;

string RevIt(char a[], int n)
{
	stringstream stream;

        if( n<=0 )
             return "";

	n--;
	stream << a[n] ;
	if(n > 0)
		stream << RevIt( a , n );
  
	return stream.str();
}

int main()
{
	cout << RevIt("ABCD",4) << "\t" << RevIt("123456789",9) ;

	while(1);

    return 0;
}

edit: actually this will only work once;)

edit 2: fixed

[ne555]

RevIt("",0);

[Jikax]

Crash....

[Lynx876]

Easy fix?

Add this on line 8:

if( n <= 0 )
    return;

[Jikax]

Your right, I was being lazy...

[Lynx876]

lol! Not too lazy, I learnt something from your effert to code the above (:

[Jikax]

Good to hear that!

[Lynx876]

Sorry if I'm hijacking this thread, but...

In the above code, wouldn't it be better to create the stringstream as a static variable, so that it's just changed rather than recreated each run of the function?

Depending on the size of the char-array, there could be an efficiency issue?

[Jikax]

I did that just moments ago... The point is the stream cannot be reset when it is completed...
This causes the result to be deleted before it is returned...