//【初心者歓迎】C/C++室 Ver.80【環境依存OK】
//http://t...content-available-to-author-only...h.net/test/read.cgi/tech/1348161305/458
//
//458 名前：デフォルトの名無しさん[sage] 投稿日：2012/10/26(金) 18:46:38.87
//ofstreamまたはifstreamでファイルが開けなかった時にcloseする必要ってありますか？
//
//// 例
//ofstream ofs("test.txt");
//if (ofs.fail()) {
//　　ofs.close(); // ←これ
//}

//Example for VS2010C++
#include <fstream>
#include <ios>
#include <iostream>

#include <Shlwapi.h>
#pragma comment(lib, "Shlwapi.lib")

void FileExist(const char fname[])
{
    bool fileexists;

	fileexists = (::PathFileExistsA(fname) == TRUE ? true : false);
	std::cout << fname << " " << (fileexists ? "" : "does not ") << "exist" << (fileexists ? "s" : "") << "." << std::endl;

	return;
}

void ShowStates(std::ifstream *ifs)
{
	std::cout << "\tifs.is_open() is " << ifs->is_open() << "." << std::endl;
	std::cout << "\tstate of bits: " << ((ifs->rdstate() & std::ios_base::eofbit) == std::ios_base::eofbit ? "eof" : "   ");
	std::cout << " " << ((ifs->rdstate() & std::ios_base::failbit) == std::ios_base::failbit ? "fail" : "    ");
	std::cout << " " << ((ifs->rdstate() & std::ios_base::badbit) == std::ios_base::badbit ? "bad" : "   ");
	std::cout << " " << (ifs->rdstate() == std::ios_base::goodbit ? "good" : "") << std::endl;
	std::cout << "\tifs.fail() is " << ifs->fail() << "." << std::endl;

	return;
}

int main(void)
{
	const char ifname1[] = "main.cpp";
	const char ifname2[] = "xxx";
	const char ifname3[] = "yyy";

	FileExist(ifname1);
	FileExist(ifname2);
	FileExist(ifname3);
	std::cout << std::endl;

	std::cout << std::boolalpha;
	std::cout << "Example 1:" << std::endl;
	{
		std::ifstream ifs(ifname1);
		std::cout << "Create std::ifstream ifs with \"" << ifname1 << "\"." << std::endl;
		ShowStates(&ifs);
		ifs.open(ifname2);
		std::cout << "ifs.open(" << ifname2 << ") is " << ((ifs.rdstate() & std::ios_base::failbit) == std::ios_base::failbit ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
		ifs.clear();
		std::cout << "Clear state of bits." << std::endl;
		ShowStates(&ifs);
		ifs.close();
		std::cout << "ifs.close() is " << ((ifs.rdstate() & std::ios_base::failbit) == std::ios_base::failbit ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
	}
	std::cout << std::endl;
	std::cout << "Example 2:" << std::endl;
	{
		std::ifstream ifs(ifname1);
		std::cout << "Create std::ifstream ifs with \"" << ifname1 << "\"." << std::endl;
		ShowStates(&ifs);
		std::cout << "ifs.rdbuf()->open(" << ifname2 << ") is " << (ifs.rdbuf()->open(ifname2, std::ios_base::in) == NULL ? "False" : "Success") << "." << std::endl;
		ShowStates(&ifs);
		std::cout << "ifs.rdbuf()->close() is " << (ifs.rdbuf()->close() == NULL ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
	}
	std::cout << std::endl;
	std::cout << "Example 3:" << std::endl;
	{
		std::ifstream ifs(ifname1);
		std::cout << "Create std::ifstream ifs with \"" << ifname1 << "\"." << std::endl;
		ShowStates(&ifs);
		ifs.close();
		std::cout << "ifs.close() is " << ((ifs.rdstate() & std::ios_base::failbit) == std::ios_base::failbit ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
		ifs.open(ifname2);
		std::cout << "ifs.open(" << ifname2 << ") is " << ((ifs.rdstate() & std::ios_base::failbit) == std::ios_base::failbit ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
		ifs.close();
		std::cout << "ifs.close() is " << ((ifs.rdstate() & std::ios_base::failbit) == std::ios_base::failbit ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
	}
	std::cout << std::endl;
	std::cout << "Example 4:" << std::endl;
	{
		std::ifstream ifs(ifname1);
		std::cout << "Create std::ifstream ifs with \"" << ifname1 << "\"." << std::endl;
		ShowStates(&ifs);
		std::cout << "ifs.rdbuf()->close() is " << (ifs.rdbuf()->close() == NULL ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
		std::cout << "ifs.rdbuf()->open(" << ifname2 << ") is " << (ifs.rdbuf()->open(ifname2, std::ios_base::in) == NULL ? "False" : "Success") << "." << std::endl;
		ShowStates(&ifs);
		std::cout << "ifs.rdbuf()->close() is " << (ifs.rdbuf()->close() == NULL ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
	}
	std::cout << std::endl;
	std::cout << "Example 5:" << std::endl;
	{
		std::ifstream ifs(ifname3);
		std::cout << "Create std::ifstream ifs with \"" << ifname3 << "\"." << std::endl;
		ShowStates(&ifs);
		ifs.clear();
		std::cout << "Clear state of bits." << std::endl;
		ShowStates(&ifs);
		ifs.close();
		std::cout << "ifs.close() is " << ((ifs.rdstate() & std::ios_base::failbit) == std::ios_base::failbit ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
	}
	std::cout << std::endl;
	std::cout << "Example 6:" << std::endl;
	{
		std::ifstream ifs(ifname3);
		std::cout << "Create std::ifstream ifs with \"" << ifname3 << "\"." << std::endl;
		ShowStates(&ifs);
		std::cout << "ifs.rdbuf()->close() is " << (ifs.rdbuf()->close() == NULL ? "Fail" : "Success") << "." << std::endl;
		ShowStates(&ifs);
	}
	return 0;
}

//OUTPUT
//==========

//main.cpp exists.
//xxx exists.
//yyy does not exist.
//
//Example 1:
//Create std::ifstream ifs with "main.cpp".
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.open(xxx) is Fail.
//        ifs.is_open() is true.
//        state of bits:     fail
//        ifs.fail() is true.
//Clear state of bits.
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.close() is Success.
//        ifs.is_open() is false.
//        state of bits:              good
//        ifs.fail() is false.
//
//Example 2:
//Create std::ifstream ifs with "main.cpp".
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.rdbuf()->open(xxx) is False.
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.rdbuf()->close() is Success.
//        ifs.is_open() is false.
//        state of bits:              good
//        ifs.fail() is false.
//
//Example 3:
//Create std::ifstream ifs with "main.cpp".
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.close() is Success.
//        ifs.is_open() is false.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.open(xxx) is Success.
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.close() is Success.
//        ifs.is_open() is false.
//        state of bits:              good
//        ifs.fail() is false.
//
//Example 4:
//Create std::ifstream ifs with "main.cpp".
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.rdbuf()->close() is Success.
//        ifs.is_open() is false.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.rdbuf()->open(xxx) is Success.
//        ifs.is_open() is true.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.rdbuf()->close() is Success.
//        ifs.is_open() is false.
//        state of bits:              good
//        ifs.fail() is false.
//
//Example 5:
//Create std::ifstream ifs with "yyy".
//        ifs.is_open() is false.
//        state of bits:     fail
//        ifs.fail() is true.
//Clear state of bits.
//        ifs.is_open() is false.
//        state of bits:              good
//        ifs.fail() is false.
//ifs.close() is Fail.
//        ifs.is_open() is false.
//        state of bits:     fail
//        ifs.fail() is true.
//
//Example 6:
//Create std::ifstream ifs with "yyy".
//        ifs.is_open() is false.
//        state of bits:     fail
//        ifs.fail() is true.
//ifs.rdbuf()->close() is Fail.
//        ifs.is_open() is false.
//        state of bits:     fail
//        ifs.fail() is true.