[C++知识库][C++] windows.h实现文件读写

额

话说C/C++的文件读写本来就是基于平台的API的吧

代码

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

struct _File
{
	LPCSTR filename;
	HANDLE handle = nullptr;
};
typedef _File* File;

File open(LPCSTR filename,bool read_mode);
LPSTR read(File file);
void write(File file, LPCSTR text);
void close(File& file);

int main()
{
	File fw = open("a.txt",false);
	write(fw, "text");
	close(fw);
	
	File fr = open("a.txt",true);
	LPSTR text = read(fr);
	std::cout << text << std::endl;
	GlobalFree(text);
	close(fr);
	return 0;
}

File open(LPCSTR filename,bool read_mode)
{
	if (filename != nullptr)
	{
		File result = new _File;
		result->filename = filename;
		result->handle = CreateFile(filename,(read_mode ? GENERIC_READ : GENERIC_WRITE), 0, 0,(read_mode ? OPEN_EXISTING : CREATE_ALWAYS),FILE_ATTRIBUTE_NORMAL, 0);
		if (result->handle == INVALID_HANDLE_VALUE) return nullptr;
		return result;
	}
	std::cout << "filename is null" << std::endl;
	return nullptr;
}

LPSTR read(File file)
{
	if (file != INVALID_HANDLE_VALUE)
	{
		size_t file_size = GetFileSize(file->handle, nullptr);
		if (file_size == INVALID_FILE_SIZE)
		{
			std::cout << "file size is INVALID_FILE_SIZE" << std::endl;
			return nullptr;
		}
		
		LPSTR result = (LPSTR)GlobalAlloc(GPTR,file_size + 1);
		if(ReadFile(file->handle,result,file_size,nullptr,nullptr) == 0)
		{
			std::cout << "Failed to read file:\"" << file->filename << "\"" << std::endl;
			delete[] result;
			return nullptr;
		}
		
		result[file_size] = '\0';
		return result;
		
	}
	return nullptr;
}

void write(File file, LPCSTR text)
{
	if (file != INVALID_HANDLE_VALUE && text != nullptr)
	{
		WriteFile(file->handle, text, strlen(text), nullptr, nullptr);
	}
}

void close(File& file)
{
	if (file != nullptr)
	{
		if (file->handle != INVALID_HANDLE_VALUE) CloseHandle(file->handle);
		delete file;
		file = nullptr;
	}
}

运行结果

控制台

text

--------------------------------
Process exited after 0.6997 seconds with return value 0
请按任意键继续. . .

a.txt

text

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