Thread: Win32 file handling

I was wondering whether there is a way to do file input/output with Win32/C++? For example, in a console C++ program, I can fo this:

ofstream write;
write.open ("file.txt");
myfile << "Hello";
myfile.close();

However, when I try to use the above functions in a Win32 program, it will not compile. How do I open and write to/read from a text file in Win32?

Thanks.

I have a program which is instructed to do the above when I press a button in my Win32 program:

Code:

case IDC_WRITE:
				

ofstream write;
write.open ("file.txt");
write << "Hello";
write.close();
					

break;

Here are the errors I get:

Code:

c:\documents and settings\xp\my documents\visual studio 2008\projects\setup2\setup2\main.cpp(42) : error C2065: 'ofstream' : undeclared identifier
c:\documents and settings\xp\my documents\visual studio 2008\projects\setup2\setup2\main.cpp(42) : error C2146: syntax error : missing ';' before identifier 'write'
c:\documents and settings\xp\my documents\visual studio 2008\projects\setup2\setup2\main.cpp(42) : error C2065: 'write' : undeclared identifier
c:\documents and settings\xp\my documents\visual studio 2008\projects\setup2\setup2\main.cpp(43) : error C2065: 'write' : undeclared identifier
c:\documents and settings\xp\my documents\visual studio 2008\projects\setup2\setup2\main.cpp(43) : error C2228: left of '.open' must have class/struct/union
        type is ''unknown-type''
c:\documents and settings\xp\my documents\visual studio 2008\projects\setup2\setup2\main.cpp(45) : error C2228: left of '.close' must have class/struct/union
        type is ''unknown-type''

Console style i/o won't work in a windows program, because there's no console window.

You should take itsme's suggestion and read up on the API calls.

But you can also use C style fopen(), fprintf(), fread(), fwrite(), fclose() etc. (and their C++ equivalents) as these don't pass text through the console.

#include <fstream>

and your done

OK, I just changed it for this:

Code:

FILE * pFile;
pFile = fopen("file.txt","w");
fwrite (buf , 1 , sizeof(buf) , pFile ); // 'buf' is a char* which takes its value from a text box that the user types into.
fclose (pFile);

It works fine (it creates a text file and outputs the value of 'buf' to it) but I get a warning:

Code:

warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
        c:\program files\microsoft visual studio 9.0\vc\include\stdio.h(237) : see declaration of 'fopen'

Is it still OK to use the fopen() function, or is it likely to cause problems?

Never mind - I changed it to this:

Code:

FILE * pFile;
fopen_s(&pFile,"file.txt","w");
fwrite (buf , 1 , sizeof(buf) , pFile );
fclose (pFile);

...and it seems to do the same thing - is this right?

Thanks for your help, everyone.

Originally Posted by george7378

Never mind - I changed it to this:

Code:

FILE * pFile;
fopen_s(&pFile,"file.txt","w");
fwrite (buf , 1 , sizeof(buf) , pFile );
fclose (pFile);

...and it seems to do the same thing - is this right?

Thanks for your help, everyone.

There you go....
fopen is depricated because of the possibility of a buffer overrun in the filename.

Originally Posted by bithub

It is only deprecated when you use a Microsoft compiler.

And guess which compiler our friend is using...
For you "it's only"... for him it's 100%