CODEWITHSUNDEEP
cwinapifile-io
Sergio Calderon
Sergio Calderon

Reputation: 867

Use StringCchCat function with CreateFile

I have the following code to write a simple TXT using the CreateFile function from the WinAPI:

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

#include <string.h>
#include <tchar.h>
#include <strsafe.h>
#include <iostream>


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {

    LPCTSTR lpFileName = L"C:\\MyTest.txt";
    DWORD dwDesiredAccess = GENERIC_READ | GENERIC_WRITE;
    DWORD dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
    LPSECURITY_ATTRIBUTES lpSecurityAttributes = NULL;
    DWORD dwCreationDisposition = CREATE_NEW;
    DWORD dwFlagsAndAttributes = FILE_ATTRIBUTE_NORMAL;
    HANDLE hTemplateFile = NULL;

    HANDLE C=CreateFile(lpFileName, dwDesiredAccess, dwShareMode, lpSecurityAttributes,
        dwCreationDisposition, dwFlagsAndAttributes, hTemplateFile);

    DWORD Er=GetLastError();

    char *pMsg = NULL;

    FormatMessageW(
        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_ARGUMENT_ARRAY | FORMAT_MESSAGE_ALLOCATE_BUFFER,
        NULL,
        Er,
        LANG_SYSTEM_DEFAULT,
        (LPWSTR)&pMsg,
        0,
        NULL
        );

    if (C != INVALID_HANDLE_VALUE)

    {
        MessageBox(NULL, (LPCTSTR)pMsg, L"Explorando la API", MB_ICONINFORMATION);
    }
    else
    {

        MessageBox(NULL, (LPCTSTR)pMsg, L"Explorando la API", MB_ICONINFORMATION);
    }


    CloseHandle(C);

}

The question is: How can I use StringCchCat function to pass a customized string to the lpFile name?

I would like to read any number from a Registry Key (Using the RegQueryValue) and give a name to the file. For example, if I read "1" form a DemoValue, the TXT name would be: MyText1.txt or MyText(1).txt.

Can you help me? Thanks!

Upvotes: 0

Views: 262

Answers (1)

Jabberwocky
Jabberwocky

Reputation: 50882

You probably want to use StringCbPrintf instead of StringCchCat.

int const filenamesize = 30;
TCHAR filename[filenamesize]; 
StringCbPrintf(filename, filenamesize * sizeof(TCHAR), TEXT("Myfile(%d).txt", somevalue);
// e.g: filename contains a "Myfile(1).txt" if 'somevalue' contains 1
...
HANDLE c = CreateFile(filename, ...) ;

Upvotes: 1

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