C++Talk.NET

Paul Rosen · Guest

I have some old code (that works just fine!), but it uses FILE* and
CString to read the contents of a relatively small file to a string in a
single call. Its signature is:

bool ReadFileToString(const CString& csFilename, CString& csContents);

I'd like to change that, though, to use std::string and std:ifstream.
The routine should be as efficient as possible with little copying of data.

I'd like the signature of the routine to be:

bool ReadFileToString(const std::string& strFilename, std::string&
strContents);

The approach that occurs to me is:

0) open the file in binary mode
1) seek to the end of the file to get the length
2) resize a stack variable of type std::vector<char> to the length
3) seek back to the beginning
4) read that many characters into the vector
5) copy the contents of the vector into strContents, translating rn
into n

There has got to be a better way, particularly since the companion
routine was so easy.

void WriteStringToFile(const std::string& strFilename, const
std::string& strContents)
{
std::ifstream ifs(strFilename);
ifs << strContents;
}

Any suggestions?

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Carl Barron · Guest

In article <l63ff.1310$wf.1155 (AT) newsread3 (DOT) news.atl.earthlink.net>, Paul
Rosen <prosen (AT) fte (DOT) com> wrote:

G.J. Giezeman · Guest

Paul Rosen wrote:

Yuri Khan · Guest

Paul Rosen wrote:

Pramod · Guest

Try this

void WriteStringToFile(const std::string& strFilename, const
std::string& strContents)
{
std::ifstream ifs(strFilename);
strFilename = std::string ( std::istreambuf_iterator<char>( ifs ),
std::istreambuf_iterator<char>( ) );
}

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kanze · Guest

Paul Rosen wrote:

mzdude · Guest

Pramod wrote:

Victor Bazarov · Guest

mzdude wrote:

fanofvc · Guest

#include <fstream>
#include <iostream>
#include <sstream>
#include <exception>
#include <vector>
#include <string>
using namespace std;
bool ReadFileToString(const std::string& strFilename, std::string&
strContents)
{
fstream fs;
try
{
fs.open(strFilename.c_str(), ios::in|ios::binary );
if(!fs)
{
ostringstream ostr;
ostr << "Cannot open File:" << strFilename << "!" << endl;
string ostrMsg = ostr.str();
throw runtime_error(ostrMsg);
}

}
catch ( runtime_error &e )
{
cout << e.what() << endl;
return false;
}
fs.seekg(0,ios::beg);
streampos begin = fs.tellg();
fs.seekg(0,ios::end);
streampos end = fs.tellg();
size_t nLength = end-begin;
vector fs.seekg(0,ios::beg);
char p;
int iLen = 0;
while(fs.get(p))
{
vecFileContent[iLen++] = p;

}

vector <char>::iterator iter = vecFileContent.begin();

while(iter!=vecFileContent.end())
{
if(static_cast<int>(*iter)=='0x0d' &&static_cast<int>(*(iter+1))
== '0x0a')
{
strContents.push_back(*(++iter++));
}
else
{
strContents.push_back(*(iter++));
}

}

fs.close();
return true;
}

void WriteStringToFile(const std::string& strFilename, const
std::string& strContents)
{
std::ofstream ofs(strFilename.c_str());
ofs << strContents;

}

int main()
{
string strBuf;
string strFileName("info.dat");
int iRet = ReadFileToString(strFileName,strBuf);
if(iRet == true)
WriteStringToFile("info1.dat",strBuf);

}

they work fine!

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