I have to deal with large files compressed with gzipped. I need to access a subset of the lines, not necessarily in order. Thus, I was thinking to go through all the file once while recording the stream position at the lines I am interested in. And then, to use these streams positions to quickly retrieve the information I need.
For this, I am using gzstream. But unfortunately tellg doesn't seem to work with this wrapper:
#include <iostream>
#include <fstream>
using namespace std;
#include <gzstream.h>
int main (int argc, char ** argv)
{
string inFile;
string line;
system ("rm -f infile1.txt; echo \"toto1\ntoto2\ntoto3\" > infile1.txt");
inFile = "infile1.txt";
ifstream inStream;
inStream.open (inFile.c_str());
cout << inStream.tellg () << endl;
getline (inStream, line);
cout << inStream.tellg () << endl;
inStream.close ();
system ("rm -f infile1.gz; echo \"toto1\ntoto2\ntoto3\" | gzip > infile1.gz");
inFile = "infile1.gz";
igzstream igzStream;
igzStream.open (inFile.c_str());
cout << igzStream.tellg () << endl;
getline (igzStream, line);
cout << igzStream.tellg () << endl;
igzStream.close ();
return 0;
}
This code returns this:
$ gcc -Wall test.cpp -lstdc++ -lgzstream -lz
$ ./a.out
0
6
18446744073709551615
18446744073709551615
Is there a way to make this work with igzstream? Or should I use Boost gzip filters instead? Any code snippet would be greatly appreciated ;)
