Help with Error - Binary to Character Converter

Hi. I wrote a binary to character converter program but I have a problem - after I type in the binary (e.g. 01000001) the program stops with an error. I ran it in win XP and linux but both give error.

The errors:
XP:

F:\>bin2char-0.1
Enter string to convert : 01000001

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.


and linux:

[dvldrmmr@myhost /]# ./bin2char-0.1
Enter string to convert : 01000001
Aborted


Any ideas why I get an error? I wrote an *almost* identical app in VB (basic vs. c++) and it worked fine.

My code (I know its not too pretty ):

Code:

/***********************************************************/
/* bin2char-0.1.cpp - Binary to Character Converter v. 0.1 */
/***********************************************************/
#include <iostream>
#include <cmath>
#include <string>
using namespace std;

int main()
{ string bin_stream, char_stream;
  int ascii_num, char_start;
  int count = 0;
  char ch;

  cout << "Enter string to convert : ";
  cin >> bin_stream;
  if(bin_stream.length() % 8 != 0){
    cout << "Incorrect input string!!\n";
    return 0; }
  for(int i = bin_stream.length(); i > 0; i - 8){
    for(int j = 0; j <= 7; j++){
      char_start = count * j + 1;
      ch = bin_stream.at(char_start + j);
      if(ch == '1'){ ascii_num += (int)(pow((double)2,j)); }
    }
    count++;
    char_stream += (char)ascii_num;
  }
  cout << "Converted string:\n" << char_stream << endl;
  return 0;
}

Is it my code?

Any help appreciated. Thanks.

Welcome to the forums!

Code:

  for(int i = bin_stream.length(); i > 0;i - 8)

The expression i - 8 does not change the value of i, so your loop is endless. You are adding to a std::string in this endless loop, so eventually it will run out of memory and the result will likely be non-optimal.

Possibly, you want i -= 8 which is the equivalent of i = i - 8.

Code:

char_start = count * j + 1;

I think you want count * 8 instead of count * j.

Thanks. It runs in windows now, I'll check linux later after I fix the conversion - it ouputs a bunch of gibberish. Thanks again for your help.

Ok. I fixed the conversion. Thanks again for your help anonytmouse. Much appreciated.

FYI - There are two secret functions in <cstdlib> that will convert from any* base: strtoul() = String To Unsigned Long, and strtol() = String to Long.

I call them secret functions, because I ran-across strtoul() in a program, but couldn't find it in any of my C++ books. So I started searching for a complete C++ reference book. I've never found a complete book, but I did find Dinkumware.com, which does seem to be a complete online reference.

There is no complimentary standard C++ function to output/display a number in any base. If you have a Microsoft compiler, _itoa() = Integer To ASCII, will do it. For binary display/output <bitset> is standard.

*Any base between 2 and 36 (base-2 to base-z.) [Corrected. Thanks, Dave.]

Thanks. I'll have to look into that. Do you happen to know any tutorials about <bitset>?

I don't know of any tutorials, but here's a sample program that uses both strtoul() and <bitset>. I think I learned about <bitset> from a book: The C++ Standard Library, A Tutorial and Reference, by Nicolai Josuttis. There is much more to <bitset>, as it's a special class, not just a function.

Thanks. That helps a lot. One ? though. in this code

Code:

cout << "\t" << dec << x << "\t\t Decimal" << endl;
cout << "\t" << oct << x << "\t\t Octal" << endl;
cout << "\t" << hex << x << "\t\t Hex" << endl;
cout << "\t" << bitset<MAX_BITS>(x) << "\t Binary (LSB)" << endl;

what are dec, oct, and hex. Are they similar to doing this

Code:

printf("%X",num); // outputs num in hex format

for hex anyway? So therefore kinda like format specifiers?