[Java] making the text backwards - need help on project

Here's another obvious way, in C++ :wink:

PHP Code:

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#include <iostream>
#include <cstdlib>
#include <string>

using namespace std;

int main()
{
   string str("abcdefghijklmnopqrstuvwxyz");

   int sz = str.size();
   for (int i = 2 - sz; i < sz - 1; i++)
     {
        int a(sz - abs(i) - 1);
        int b(sz - abs(i) - 2);

        str[a] ^= str[b];
        str[b] ^= str[a];
        str[a] ^= str[b];
     }

   cout << str << endl;
   return 0;
} 


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Quote:

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Originally Posted by Negata

PHP Code:

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        str[a] ^= str[b];
        str[b] ^= str[a];
        str[a] ^= str[b]; 


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XOR, wat?

PHP Code:

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#include <stdio.h>
#include <string>

int main(int argc, char *argv[])
{
   char *szInput = (char *)malloc (512);
   char *szOutput = (char *)malloc (512);
   memset (szOutput, 0, 512);
   scanf ("%[^\n]", szInput);
  
   for (int i = strlen(szInput); i >= 1; --i) szOutput[i] = szInput[i];
   printf ("Original: %s\nReversed: %s\n", szInput, szOutput);
   free (szOutput);
   free (szInput);
   return 0;
} 


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Quote:

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Originally Posted by Theoretical

XOR, wat?

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He's trying to be clever. It's a way to exchange 2 variables without using a temporary variable.


Ok, let's review:

A ^ B = C
C ^ A = B
C ^ B = A

Now, two variables X and Y, we want to exchange them using XOR:

X = X ^ Y = Z (just as a reminder that it's the xor product)

Now, X is the Z value here, now we want to move X into Y:
Y = Y ^ Z = X

Now, X = Z and Y = X, one final move to make X be our Y value:

X = Z ^ Y = Z ^ X = Y


So now our two variables have been exchanged. It's a bit confusing calling it Z^Y on the last step because Y means X, it's notational, I didn't care to do it properly by denoting the original values as X_0 and Y_0 (primarily because subscripts are a pain in the ass to do in vBulletin without a math addon).

Quote:

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Originally Posted by jMerliN

He's trying to be clever. It's a way to exchange 2 variables without using a temporary variable.


Ok, let's review:

A ^ B = C
C ^ A = B
C ^ B = A

Now, two variables X and Y, we want to exchange them using XOR:

X = X ^ Y = Z (just as a reminder that it's the xor product)

Now, X is the Z value here, now we want to move X into Y:
Y = Y ^ Z = X

Now, X = Z and Y = X, one final move to make X be our Y value:

X = Z ^ Y = Z ^ X = Y


So now our two variables have been exchanged. It's a bit confusing calling it Z^Y on the last step because Y means X, it's notational, I didn't care to do it properly by denoting the original values as X_0 and Y_0 (primarily because subscripts are a pain in the ass to do in vBulletin without a math addon).

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I know what XOR is, I'm asking why he's trying to use it...