Adding binary values from a file
 

Hello, I'm working o a function that takes a file with binary numbers and returns the sum of those numbers. Here's where I'm now

int Sum (char *fileName)

{

char * numEnd;

long temp(0);

int result(0);

string line;

 ifstream file (fileName);

  if (file.is_open())

  {

    while (! file.eof() )

    {

      getline (file,line);

//Convert line to an long and sum up with the rest 

      temp = strtol(line, &numEnd, 2);

      result = result + temp;    

//Done

    }

// close the stream

    file.close();

  }

return result;

}

and here's an error I'm getting when building it:
error C2664: 'strtol' : cannot convert parameter 1 from 'std::string' to 'const char *'

I thought strtol needed a pointer to the string, but changing line to pointer to line didn't help. Anyone can point me in a right direction?

Re: Adding binary values from a file
 

OK, I got it. Any comments on code quality or improvements are still welcome!

int Sum (char *fileName)

{

char * numEnd;

long temp(0);

int result(0);

string line;

 ifstream file (fileName);

  if (file.is_open())

  {

    while (! file.eof() )

    {

      getline (file,line);

//Convert line to an int and sum up with the rest 

      char *linePt = &line[0];

      temp = strtol(linePt, &numEnd, 2);

      result = result + temp;    

//Done

    }

// close the stream

    file.close();

  }

return result;

}

Re: Adding binary values from a file
 

It's because strtol was an old C function written far before C++ strings were invented. Although C++ strings have overloaded functions to make transitions from the older-style char strings to C++ strings and vice-versa, this problem can't be as transparently solved when passing a C++ string to a function that is expecting a char string. To remedy this, C++ strings include a nifty member function called c_str() that can quickly return the char string equivalent. Thus, you could code it like this:

temp = strtol(line.c_str(), &numEnd, 2);

Better yet, use the C++ streams, the modern equivalent of a lot of the old C string functions, rather than mixing C and C++.

Hope this helps