C++ file I/O is tougher than C file I/O.
So in C++, creating a new library for file I/O is useful or not? I mean <fstream>
Can anyone please tell are there any benefits in C++ file I/O ?
Opinion
I don't know of any real project that uses C++ streams. They are too slow and difficult to use. There are several newer libraries like FastFormat and the Boost version that claim to be better there was a piece in the last ACCU Overload magazine about them. Personally I have used the c FILE library for the last 15 years or so in C++ and I can see no reason yet to change.
Speed
Here is small test program (I knock together quickly) to show the basic speed problem:
#include <stdio.h>
#include <time.h>
#include<iostream>
#include<fstream>
using namespace std;
int main( int argc, const char* argv[] )
{
const int max = 1000000;
const char* teststr = "example";
int start = time(0);
FILE* file = fopen( "example1", "w" );
for( int i = 0; i < max; i++ )
{
fprintf( file, "%s:%d\n", teststr, i );
}
fclose( file );
int end = time(0);
printf( "C FILE: %ds\n", end-start );
start = time(0);
ofstream outdata;
outdata.open("example2.dat");
for( int i = 0; i < max; i++ )
{
outdata << teststr << ":" << i << endl;
}
outdata.close();
end = time(0);
printf( "C++ Streams: %ds\n", end-start );
return 0;
}
And the results on my PC:
C FILE: 5s
C++ Streams: 260s
Process returned 0 (0x0) execution time : 265.282 s
Press any key to continue.
As we can see just this simple example is 52x slower. I hope that there are ways to make it faster!
NOTE: changing endl to '\n' in my example improved C++ streams making it only 3x slower than the FILE* streams (thanks jalf) there may be ways to make it faster.
Difficulty to use
I can't argue that printf() is not terse but it is more flexible (IMO) and simpler to understand, once you get past the initial WTF for the macro codes.
double pi = 3.14285714;
cout << "pi = " << setprecision(5) << pi << '\n';
printf( "%.5f\n", pi );
cout << "pi = " << fixed << showpos << setprecision(3) << pi << '\n';
printf( "%+.3f\n", pi );
cout << "pi = " << scientific << noshowpos << pi<< '\n';
printf( "%e\n", pi );
The Question
Yes, may be there is need of a better C++ library, may be FastFormat is that library, only time will tell.
dave