c++ stream操作杂记

包含简单的读写文件，供初学者入门，stream目前包含三种，终端，文件，内存，注意宽字节。

// "C:\Program Files (x86)\Microsoft Visual C++ Build Tools\vcbuildtools.bat"

// "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat"

// g++ -O2 -std=c++11 lock.cpp

// cl.exe /O2 /std:c++11 lock.cpp

// cl.exe /O2 /std:c++14 stream.cpp

#include <iostream> // iostream istream ostream | wxxx

#include <fstream> // fstream ifstream ofstream | wxxx

#include <sstream> // stringstream istringstream ostringstream | wxxx

#include <string>

#include <ctime>

// #include <cstddef>

// #include <cstring>

using namespace std;

// wstring => string

std::string wstring2string( const std::wstring &ws)

{

std::string strLocale = setlocale(LC_ALL, "");

const wchar_t *wchSrc = ws. c_str();

int nDestSize = wcstombs( NULL, wchSrc, 0) + 1;

char *chDest = new char[nDestSize](); // vs init zero

wcstombs(chDest, wchSrc, nDestSize);

std::string strResult = chDest;

delete[] chDest;

setlocale(LC_ALL, strLocale. c_str());

return strResult;

}

// string => wstring

std::wstring string2wstring( const std::string &s)

{

std::string strLocale = setlocale(LC_ALL, "");

const char *chSrc = s. c_str();

int nDestSize = mbstowcs( NULL, chSrc, 0) + 1;

wchar_t *wchDest = new wchar_t[nDestSize]();

mbstowcs(wchDest, chSrc, nDestSize);

std::wstring wstrResult = wchDest;

delete[] wchDest;

setlocale(LC_ALL, strLocale. c_str());

return wstrResult;

}

bool logFile(string fileName, string fileText, int mode)

{

//fstream oftextStream(fileName.c_str(), mode); // ofstream::out ofstream::app

fstream oftextStream(fileName. c_str(), (ios_base::openmode)mode);

if (oftextStream)

{

char mbstr[ 64] = { ' \0 '};

time_t timer = time( NULL); // ctime(&timer);// unsafe and endeith newline

std::strftime(mbstr, sizeof(mbstr), " %a %F % T", std::localtime( &timer));

oftextStream << mbstr << " " << fileText. c_str() << endl;

oftextStream. close();

}

return true;

}

inline std::ostream & putline(std::ostream &os, std::string const &line)

{

return os << line << std::endl;

}

bool dealFile(string fileName, string fileText)

{

ostringstream stmtext;

stmtext << ";" << endl;

string strstext = stmtext. str();

const char *cstrs = strstext. c_str();

fstream iftextStream(fileName. c_str(), ofstream::in);

if (iftextStream)

{

//iftextStream.read(chartext, sizeof(chartext)); char chartext[64] = { 0 };

// iftextStream >> strstext; // only read end if space

getline(iftextStream, strstext);

iftextStream. close();

}

//fstream with args

fstream oftextStream(fileName. c_str(), ofstream::out);

if (iftextStream)

{

//iftextStream.write(chartext, sizeof(chartext)); char chartext[64] = { 0 };

oftextStream << fileText << endl; // or putline(oftextStream, fileText);

oftextStream. flush(); // please quickly flush to file

oftextStream. close();

}

//ifstream ofstream with args

string lineText = "lineText";

ifstream itextStream(fileName. c_str());

if ( !itextStream)

{

return false;

}

while ( getline(itextStream, strstext))

{ //! textAStream.eof();textAStream.read(charStrs, charSize);

string strNum = (strstext);

}

itextStream. close();

//ifstream ofstream with args

ofstream otextStream(fileName. c_str());

if ( !otextStream)

{

return false;

}

putline(otextStream, lineText); // or otextStream << fileText << endl;

otextStream. flush(); //please quickly flush to file

otextStream. close();

return true;

}

int main( int argc, char *argv[])

{

dealFile( "test.txt", "Hello world");

logFile( "test.txt", "Hello world", fstream::out);

logFile( "test.txt", "Hello world", fstream::app);

logFile( "test.txt", "Hello world", fstream::app);

return 0;

}

pasting