Writting in files

Casiopea · Feb 9, 2005

I have created a CFile object and I want to write in it, in fact I get it, but I cannot write on differente lines although I add "file.Write("\n",sizeof("\n"))" I just see
inside the file one very long line.
How can I get it?

Another question is that I give it code for an html file, I mean, <HTML>....</HTML> and the extension is html; is that enough to open it like an html file; I see the icon associated to the file like an html, and it seems it work, but I would like to give it bold letter, center and so on.

PerFnurt · Feb 9, 2005

\n" is a pointer to a string, hence sizeof("\n") returns the size of the pointer to the string (which I guess is 4 on your system).

Anyway, in windows most applications require "\r\n" to mark a new line.

Code:

  CFile f(theFileName,CFile::modeCreate | CFile::modeWrite);
  CString s("<html>\r\n<body>\r\n<b>B</b>old\r\n</body>\r\n</html>");

  f.Write((LPCTSTR) s, s.GetLength());

or if you want to work in unicode aswell

Code:

  #include <string>
  
  // ...
  CFile f(theFileName,CFile::modeCreate | CFile::modeWrite);
  std::string s("<html>\r\n<body>\r\n<b>B</b>old\r\n</body>\r\n</html>");

  f.Write(s.c_str(), s.size());

/Per
_{www.perfnurt.se}

Salem · Feb 9, 2005

> "\n" is a pointer to a string,
String constants are arrays, so depending on the context it may or may not decay to a pointer.

> file.Write("\n",sizeof("\n"));
The first use is a decayed pointer, the second use returns the size of the array.
It is the equivalent of

Code:

char anon[] = "\n";
file.Write(anon,sizeof(anon));

Which in this case, the sizeof will result in the value 2 being returned.

One of these would perhaps be better.

Code:

file.Write("\n",strlen("\n"));
file.Write("\n",1);

--

ArkM · Feb 9, 2005

Yes, a string literal is an array of char in C/C++. Arrays are implicitly converted into pointers to base types in all contexts except sizeof operator arg. Yet another orthogonal (special) case - initializators. They are another story...
So sizeof("\n") == 2 ('\n'+zero terminator)...

PerFnurt · Feb 9, 2005

Hmmm, yes, you're right of course.

Just checked that you're all alert.

/Per
_{www.perfnurt.se}

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Writting in files

Casiopea

Programmer

PerFnurt

Programmer

Salem

Programmer

ArkM

IS-IT--Management

PerFnurt

Programmer

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