Thread: Variable Length Arrays

Hello,
Is there a way to make a (char) array with a variable length?

I'm (kind of) working on an "encryption program" that takes a file and encrypts it using a ridiculously simple algorithm (if you can even call it that).

The problem is, when it asks the user to input the file name (including the extension and directories), if the file name is longer than the array 'name1' then there is an error that pops up after the program exits (even though everything encrypts and works out OK).

Code:

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

bool badfilename = false;

class Encryption
{
     fstream file1;//source file
     fstream file2;//destination file
     
     public:
     Encryption::Encryption(char* filename1, char* filename2)
     {
          file1.open(filename1, ios::in | ios::out | ios::binary);
		  if(!file1.is_open())
		  {
			  cout << "ERROR: Cannot find file with the name of " << filename1 << "!" << endl;
			  badfilename = true;
			  return;
		  }
		  if(badfilename)
			  return;
			
          file2.open(filename2, ios::out|ios::binary);
     }     
     
     //encrypts the file
     void Encrypt(void)
     {
          char currentByte;
          bool currentBit;
          
          int index = 0;
          
          //sets the pointers to the beginning of the file
          file1.seekg (0, ios::beg);
          file2.seekp (0, ios::beg);
          
          //reads the first value
          file1.read(&currentByte, 1);
          while(file1.good())
          { 
               //loop for four bits
               for(int c = 0; c < 4; c++)
               {
                    //finds out if the first bit is a one
                    currentBit = (int)((unsigned char)currentByte / 128);
                    //shifts the byte over
                    currentByte <<= 1;
                    
                    //if the first bit was a one then we add it to the end
                    if(currentBit)
                    {
                         currentByte += 1;
                    }
               }
               
               //writes the character               
               file2.write(&currentByte, 1);
               
               //increments the pointer
               file1.seekg (++index);
               file2.seekp (index);
               
               //reads the next value
               file1.read(&currentByte, 1);
          }
     }     

     //closes both of the files
     void close(void)
     {
          file1.close();
          file2.close();
     }
};

int main( void )
{
	char name1[999999]; //IS THERE A WAY TO HAVE A VARIABLE LENGTH ARRAY?!!!!!!

    cout << "***ENCRYPTION PROGRAM***" << endl;
	cout << "Please enter the file name (including the extension):" << endl;
	cin>>name1;

	cout << endl;

    Encryption delta(name1, "output1.txt");

	if(!badfilename)
	{
    delta.Encrypt();//Encrypt the file
    delta.close();//Close the file

    Encryption gamma("output1.txt", "output2.txt");
	gamma.Encrypt();//Decrypt (by re-encrypting) output1.txt which is the encrypted version of the orignal file
	delta.close();//Again, close it.

	cout << "Succesfully encrypted file! \"output1.txt\" contains the encrypted data." << endl; //Happpy
	}
	else
	{
		cout << "Error opening file. Could not encrypt!" << endl;//Depressing
	}

	system("PAUSE");

    return 0;
}

I really just need to know if I can create an array that has a variable length.
If not, is there another more advanced data storage type?

Any and all help is appreciated!

Yes, there is. std::string is just what you need. string - C++ Reference