How to print data from stringstream to a file? - c++

Question

I have opened a file using CreateFile fn and tried to print data into the file. Since the data includes some print statements like
wprintf(L"Channel %s was not found.\n", pwsPath);
The declaration for DATA and pwsPath
#include <iostream>
#include <sstream>
using namespace std;
string data;
LPWSTR pwsPath = L"Channel1";
I tried to use stringstream to get the data and convert it to a LPCVOID to use the WriteFile fn as shown
hFile1 = CreateFile(L"MyFile.txt", // name of the write
GENERIC_WRITE, // open for writing
0, // do not share
NULL, // default security
CREATE_ALWAYS, // create new file only
FILE_ATTRIBUTE_NORMAL, // normal file
NULL);
std::stringstream ss;
ss << "Channel" << pwsPath << "was not found.";
ss >> data;
cout << data; // data contains value only till the first space i.e Channel093902
cin>>data;
bErrorFlag = WriteFile(
hFile1, // open file handle
data.c_str(), // start of data to write
dwBytesToWrite, // number of bytes to write
&dwBytesWritten, // number of bytes that were written
NULL);
Is it possible for variable data to include spaces from the stringstream ??
OR
Is there any other way other than stringstream to get the data from such print statements and write to the file as such?

Answer 1

The >> operator will deliver the next 'word' in the stream into the string object you have given it. It breaks at the first white space as you have found. There are a couple of ways to achieve what you want. The most conformant is to open the output file as an ofstream:
#include <iostream>
#include <sstream>
#include <fstream>
using namespace std;
int main()
{
std::string pwsPath { "[enter path here]" };
std::stringstream ss;
ss << "Channel " << pwsPath << " was not found.";
std::ofstream outFile("myFile.txt");
outFile << ss.rdbuf();
outFile.close();
std::ifstream inFile("myFile.txt");
cout << inFile.rdbuf();
return 0;
}
otherwise you can get the internal string from the ostringstream:
std::string myData = ss.str();
size_t dataLength = myData.length();
DWORD dwBytesWritten = 0;
BOOL bErrorFlag = WriteFile(
hFile1, // open file handle
myData.data(), // start of data to write
DWORD(dataLength), // number of bytes to write
&dwBytesWritten, // number of bytes that were written
NULL);

Answer 2

Unless you have a good reason to use CreateFile and WriteFile, consider using std objects all the way.
Your code could look like this:
#include <iostream>
#include <fstream> // add this
#include <sstream> // remove this unless used elsewhere
// your pwsPath
std::wstring path{ L"Channel1" };
std::wofstream out{ L"MyFile.txt", std::wofstream::trunc };
// skip the stringstream completely
out << "Channel " << path << " was not found."