Win32 File API

The Win32 File API provides a comprehensive set of functions for interacting with the file system on Windows. This includes operations such as creating, opening, reading, writing, and deleting files, as well as managing directories and file attributes.

Key Concepts

Understanding the following concepts is crucial when working with the Win32 File API:

• Handles: A handle is an identifier for an open file or directory. It's used in subsequent operations to refer to that specific resource.
• File Paths: Understanding absolute vs. relative paths and UNC paths is important for specifying file locations.
• File Access Rights: Functions often require specifying desired access rights (e.g., read, write, execute) and share modes.
• Overlapped I/O: For asynchronous operations, the concept of overlapped I/O and event objects is vital for efficient handling of I/O requests.

Common File Operations

Directory Operations

Manipulating directories is also a common task:

• CreateDirectory / CreateDirectoryEx: Creates a new directory.
• RemoveDirectory: Deletes an empty directory.
• GetCurrentDirectory: Retrieves the current working directory.
• SetCurrentDirectory: Changes the current working directory.
• FindFirstFile / FindNextFile: Used to enumerate files and subdirectories within a directory.

Example: Reading a File

Here's a simplified C++ example demonstrating how to read from a file:

#include <windows.h>
#include <iostream>
#include <vector>

int main() {
    HANDLE hFile = CreateFile(
        L"example.txt",           // File name
        GENERIC_READ,             // Desired access
        FILE_SHARE_READ,          // Share mode
        NULL,                     // Security attributes
        OPEN_EXISTING,            // Creation disposition
        FILE_ATTRIBUTE_NORMAL,    // Flags and attributes
        NULL                      // Template file
    );

    if (hFile == INVALID_HANDLE_VALUE) {
        std::cerr << "Error opening file: " << GetLastError() << std::endl;
        return 1;
    }

    DWORD fileSize = GetFileSize(hFile, NULL);
    if (fileSize == INVALID_FILE_SIZE) {
        std::cerr << "Error getting file size: " << GetLastError() << std::endl;
        CloseHandle(hFile);
        return 1;
    }

    std::vector<char> buffer(fileSize);
    DWORD bytesRead;

    if (ReadFile(hFile, buffer.data(), fileSize, &bytesRead, NULL) && bytesRead == fileSize) {
        std::cout.write(buffer.data(), bytesRead);
    } else {
        std::cerr << "Error reading file: " << GetLastError() << std::endl;
    }

    CloseHandle(hFile);
    return 0;
}
        

API Reference Snippet