Thread: Small program big problem :-(

I have just written small program that reads txt file and populates vector of strings (STL). Everything was ok. when I worked with small files but when I incresed size of file after 13988 lines program looks like frozen :-( Could someone put on this issue some light ? I tried to change vector to different structure i.e. list or stack but without success - stil the same behavior. Does anyone know where is problem ?

Code:

#include <string> 
#include <iostream> 
#include <ctime>
#include <fstream>
#include <vector>
#include <stdexcept> 

using namespace std;

int main(void)
{
  clock_t start, 
          end,
          time;
  char logLine[512];
  int nOfLine = 0, 
      nOfOmitedLine = 0; 
  long int i = 0; 
  vector<string> serverLog;  
  
  start = clock(); // start clock
  system ("cls"); /* Or system ("clear"); for Unix */
    
//
// Open the file and check for errors
//
  ifstream logFile("srv.log");
  if (!logFile) {
    throw invalid_argument("Unable to open file\n");
  } 

//
// read log lines from server.log to vector
//
  while(!logFile.eof()) // read log lines from server.log to vector
        {
              logFile.getline(logLine,512);
              nOfLine++;
                if  (strncmp(logLine, "T\t", 2) == 0) {
                  serverLog.push_back(logLine);
                  cout << serverLog.size() << endl;
                  } else {
                     nOfOmitedLine++;
                     }
        }         

  logFile.close();

  end = clock();   // stop clock
  time = ( end - start ) / CLOCKS_PER_SEC; //compute time of execution

  cout << "Vector size: " << serverLog.size() << endl; 
  cout << "Vector capacity: " << serverLog.capacity() << endl;
  cout << "Number of read lines: " << nOfLine << endl;
  cout << "Number of omited lines: " << nOfOmitedLine << endl;
  if (time < 1) {
     cout << "Time (sec): < 1"<< endl;
     } else {
            cout << "Time (sec): " << time << endl;
            }
    
  return(0);
}

I actually forgot when it started working and when it didn't, but the one thing that I did do was take the eof() out of the loop expression, replaced it with std::getline instead of istream::getline (this means, string's isntead of char[]'s), and then some other minor changes (substr instead of strncmp, added a catch() statement, took out self explanitory comments, whatever!)

Code:

#include <string> 
#include <iostream> 
#include <ctime>
#include <fstream>
#include <vector>

using namespace std;

int main(void)
{
	clock_t start = clock(), end, time;
	int nOfLine = 0, nOfOmitedLine = 0; 
	long int i = 0; 

	vector<string> serverLog;
	string logLine;
    
	try
	{
		ifstream logFile("C:\\a.txt");
		if (!logFile)
			throw string("Unable to open file\n");

		//
		// read log lines from server.log to vector
		//
		while(getline(logFile, logLine))
		{
			nOfLine++;
			if(logLine.substr(0, 2) == "T\t") 
			{
				serverLog.push_back(logLine);
				cout << serverLog.size() << endl;
			} 
			else 
				nOfOmitedLine++;
		}

		logFile.close();

		end = clock();
		time = ( end - start ) / CLOCKS_PER_SEC;

		cout << "Vector size: " << serverLog.size() << endl; 
		cout << "Vector capacity: " << serverLog.capacity() << endl;
		cout << "Number of read lines: " << nOfLine << endl;
		cout << "Number of omited lines: " << nOfOmitedLine << endl;


		if (time < 1) cout << "Time (sec): < 1"<< endl;
		else cout << "Time (sec): " << time << endl;
	}
	catch(string& e)
	{
		cout << e;
	}
	return 0;
}

Anyways, I think it works now that I mutilated it.

It works !!!

Thank You !!!

Glad to hear it

How you think ? Why it worked with somll files and did not work with big files ?