Files

In C++ the library that holds the files is known as the file stream library. (#include <fstream.h>) The varying operating systems can handle certain features differently. Permitted file names vary. The 8 + 3 convention is normally safe to use:

• file names have 8 characters followed by
• optional full stop followed by
• optional 3 letter extension

Permitted characters:

• Roman alphabet (upper and lower case)
• underscore
• hyphen
• dollar sign

Upper and lower case are regarded as the same. Embedded systems can be more restrictive.

The fstream library contains several classes including:

• ifstream - input file stream
• ofstream - output file stream
• fstream - file stream. Both input and output. (NB - this class has the same name as the library)

The library iostream becomes available following #include <fstream.h>. This contains the cout file for writing to the screen and cin file for reading from the keyboard. Opening and closing of these files is automatic.

Insertion operator <<

int main(int argc, char* argv[])
{ //demonstrating the insertion operator <<
  cout << "File stream input/output\n";   //Cursor moved to next line by \n
  cout << 12345;
  cout << true;   //returns a 1
  cout << 12345 << " File stream input/output\n";   //Combining insertions
  getchar();
        return 0;
}

Extraction operator >>

int main(int argc, char* argv[])
{
int Integer;
float Float;
  cout << "File stream input/output - input\n";
  cout << "Enter an integer, then press Enter: ";
  cin >> Integer;  //reads in integer from keyboard
  cout << "\nYou entered: " << Integer << "\n";

  getchar();
        return 0;
}

Insertion/Extraction and strings

These present problems with string:

• Tab and initial space characters are ignored
• None space and none tab characters are read and stored until the first space/tab is encountered

Strings containing spaces cannot be read and stored using this method.

Comments, suggestions, ideas to
Stuart Banner