DeleteFile which begin with substring - c++

Question

I want to delete all the files which begin with sub string.
CString Formatter = _T("C:\\logs\\test\\test_12-12-2018_1*.*");
DeleteFile(Formatter);
I intend to delete following files with above code
C:\logs\test\test_12-12-2018_1_G1.txt
C:\logs\test\test_12-12-2018_1_G2.txt
C:\logs\test\test_12-12-2018_1_G3.txt
C:\logs\test\test_12-12-2018_1_G4.txt
When I check error from GetLastError, I get ERROR_INVALID_NAME.
Any idea how to fix this?

Answer 1

DeleteFile doesn't take wildcards. It looks like what you need is a FindFirstFile/FindNextFile/FindClose loop to turn your wildcard into a list of full file names.
#include <windows.h>
#include <pathcch.h>
#pragma comment(lib, "pathcch.lib")
// (In a function now)
WIN32_FIND_DATAW wfd;
WCHAR wszPattern[MAX_PATH];
HANDLE hFind;
INT nDeleted = 0;
PathCchCombine(wszPattern, MAX_PATH, L"C:\\Logs\\Test", L"test_12-12-2018_1*.*");
SetCurrentDirectoryW(L"C:\\Logs\\Test");
hFind = FindFirstFileW(wszPattern, &wfd);
if(hFind == INVALID_HANDLE_VALUE)
{
// Handle error & exit
}
do
{
DeleteFileW(wfd.cFileName);
nDeleted++;
}
while (FindNextFileW(hFind, &wfd));
FindClose(hFind);
wprintf(L"Deleted %d files.\n", nDeleted);
Note that PathCchCombine, FindFirstFileW, and DeleteFileW can all fail, and robust code would check their return values and handle failures appropriately. Also, if FindNextFileW returns 0 and the last error code is not ERROR_NO_MORE_FILES, then it failed because of an actual error (not because there was nothing left to find), and that needs to be handled as well.
Also, if speed is a concern of yours (your example in your post about deleting four files in the same directory doesn't seem like it needs it), replace the line hFind = FindFirstFileW(...) with:
hFind = FindFirstFileExW(wszPattern, FindExInfoBasic, (LPVOID)&wfd, FindExSearchNameMatch, NULL, FIND_FIRST_EX_LARGE_FETCH);

Answer 2

Although you can search for the file names, and then call DeleteFile individually for each, my advice would be to use one of the Windows shell functions to do the job instead.
For example, you could use code something like this:
#define _WIN32_IE 0x500
#include <windows.h>
#include <shellapi.h>
#include <shlobj.h>
#include <iostream>
#include <string>
static char const *full_path(std::string const &p) {
static char path[MAX_PATH+2] = {0};
char *ignore;
GetFullPathName(p.c_str(), sizeof(path), path, &ignore);
return path;
}
static int shell_delete(std::string const &name) {
SHFILEOPSTRUCT op = { 0 };
op.wFunc = FO_DELETE;
op.pFrom = full_path(name);
op.fFlags = FOF_ALLOWUNDO | FOF_SILENT | FOF_WANTNUKEWARNING | FOF_NOCONFIRMATION;
return !SHFileOperation(&op);
}
int main(int argc, char **argv) {
if ( argc < 2) {
fprintf(stderr, "Usage: delete <filename> [filename ...]");
return 1;
}
for (int i=1; i<argc; i++)
shell_delete(argv[i]);
}
One obvious advantage to this is that you can pass the FOF_ALLOWUNDO flag (as I have in the code above), which moves the files to the recycle bin instead of removing it permanently. Of course, you can omit that flag if you want to the files nuked.
Depending on what you're doing, there are a few other flags that might be handy, such as FOF_FILESONLY, to delete only files, not directories that might match the wildcard you specify, and FOF_NORECURSION to have it not recurse into subdirectories at all.
Microsoft considers SHFileOperation obsolescent, and has (in Windows Vista, if memory serves) "replaced" it with IFileOperation. IFileOperation is a COM interface though, so unless you're using COM elsewhere in your code, chances are pretty good that using it will add a fair amount of extra work for (at least in this case) little or no real advantage. Especially you're already using COM, however, this might be worth considering.