Unhandled exception VS2010 C++ - c++

Question

I am trying to make a socket on windows to connect to a server.
I am using the code from msdn's website, the winsock client code.
(Link: msdn.microsoft.com/en-us/library/windows/desktop/ms737591(v=vs.100).aspx )
In any case, when I try debugging said code I get the error message:
Unhandled exception at 0x58a714cf (msvcr100d.dll) in Application.exe: 0xC0000005: Access violation reading location 0x00000032.
It asks me if I want to break or continue, if I continue the same error message simply keeps popping up. If I press break it takes me to line 1643 in the file output.c .
Simply put, I have no idea about what to do to make it work, and I'd appreciate any help given.
EDIT:
A reply to all comments given thus far:
The surrounding relevant code in output.c is:
if (flags & (FL_LONG|FL_WIDECHAR)) {
if (text.wz == NULL) /* NULL passed, use special string */
text.wz = __wnullstring;
bufferiswide = 1;
pwch = text.wz;
while ( i-- && *pwch )
++pwch;
textlen = (int)(pwch - text.wz);
/* textlen now contains length in wide chars */
} else {
if (text.sz == NULL) /* NULL passed, use special string */
text.sz = __nullstring;
p = text.sz;
while (i-- && *p) //THIS IS WHERE IT BREAKS
++p;
textlen = (int)(p - text.sz); /* length of the string */
}
This is not code that I have written but innate code that already exists.
EDIT NR 2:
This is a printscreen displaying my call stack.
I do not have 10 reputation so I cannot show the image, so here is a link to the image:
http://tinypic.com/r/5n6ww9/5
On it you can see my call stack

Answer 1

The file output.c has the code that handles the printf family of functions.
The fact that you have an error here is probably due to a malformed printf function call in your code. Maybe you have specified an invalid print format or have not provided enough arguments.
When your program crashes, click Break and look at the call stack in the debugging windows to see where - in your code - the function is called, and with what arguments.
I suspect you are trying to print a NULL string or something. When you have found the printf call (if that's what it is), edit your question to show that section of source code and/or use the debugger to examine the variables used a arguments to the function and make sure they are all correct.
Without seeing the code that you've written, at the location of the crash, it's not possible to give a more precise answer.

Answer 2

Or you may insert a null string to CString.format like below:
CString str;
str.format("%s"); //A null string
where it should be
str.format("%s",mes);
where mes is char mes[20] for example
or any other variable
So the point is there may be some mistake in CString.format or Printf
Good Luck.