winAPI

[Moony]

Hi all,

In the code below, I want to call windows API to delete a file to recycle bin. This is my first try to use winAPI. Please, can anybody tell me where is the error?

#include <stdio.h>
#include <windows.h>


int main()
{
 SHFILEOPSTRUCTA fileOp;

 fileOp.wFunc = FO_DELETE;
 fileOp.pFrom = "D:\\Documents and Settings\\Book1\\0\\0";
 fileOp.fFlags = FOF_ALLOWUNDO | FOF_NOCONFIRMATION;

 if (!SHFileOperation(&fileOp))
  printf("it is DONE!");
 else
  printf("Unwanted error happened!");
 return 0;
}

[vart]

Could you describe the error?
Do you have compilation erros?
Run=time errors?
Unwanted output?

[Moony]

Could you describe the error?
Do you have compilation erros?
Run=time errors?
Unwanted output?

Actaully none of the obove. It outputs the "Unwanted error happened" which is the condition of not satisfying the first "if". Any help?

[The Brain]

if(!SHFileOperation(&fileOp))
  printf("Unwanted error happened!");

 else
  printf("it is DONE!");

[Cactus_Hugger]

See if calling GetLastError() yeilds anything useful. That, and zero out fileOp to be sure you're not passing garbage to SHFileOperation():

SHFILEOPSTRUCTA fileOp = {0};

EDIT: @The Brain: Code that doesn't compile?

[Moony]

I added the piece of the code that you suggested, and I got the following msg:

Cannot delete a file: Cannot read from the source file or disk.

[abachler]

Try this instead:

 fileOp.pFrom = "D:\Documents and Settings\Book1\\0\\0";

[Cactus_Hugger]

fileOp.pFrom = "D:\Documents and Settings\Book1\\0\\0";

Neither \D or \B is a valid escape sequence.

Rereading the Win32 API, I must have missed this in my first post:

pFrom

Pointer to a buffer that specifies one or more source file names. Multiple names must be null-separated. The list of names must be double null-terminated.

You're not correctly giving a double null at the end of your string. This:

"D:\\Documents and Settings\\Book1\\0\\0"

Translates to the string containing:

D:\Documents and Settings\Book1\0\0(NUL)

First, it isn't double null (you may be lucky that the next byte is 0), and you're deleting a file called "0", probably not what you wanted. Try:

fileOp.pFrom = "D:\\Documents and Settings\\Book1\0";

(The string literal provides another null, for a total of two.) This for me will delete a file called "Book1".

[Moony]

I liked your post, it is really helpful, Cactus_Hugger.

You are right, it works now. I noticed that sometimes we can use \0 or \*? Compiling my code under Cygwin with gcc compiler works well with \*, but when I compile it with Microsoft visual studio compiler it works well with \0. Any thoughts?

Another question: I want to add some codes that enable me to delete the directories. What are the flages that I should add || remove?

[Cactus_Hugger]

I noticed that sometimes we can use \0 or \*? Compiling my code under Cygwin with gcc compiler works well with \*, but when I compile it with Microsoft visual studio compiler it works well with \0.

I'm not sure if I'm entirely following your question here. Start with a string literal:

"Hello World!"

Now, since the string starts and ends with quotes, you can't directly type quotes in there. So, you have what are called escape sequences, which allow you to type things easily into string literals that wouldn't otherwise be easy to do. Escape sequences start with a \. For example, to get that quote in a string:

"Hello World! is a famous \"quote\"."

There are other escape sequences, such as \0, which allows you to place nulls in a string. (Note that string literals include one at the end automatically - both of the above examples have a null at the end.) \n is a newline, and \t is a tab. Since \ starts an escape sequence, if you want a \ in a string, you must type \\. \* isn't one, and a good compiler should warn you.

esc.c:5:9: warning: unknown escape sequence '\*'

As for deleting directories, does passing the directory itself, as if it were a file, not work? If not, read the manual.