save lines in a vector

[rotundjere]

Hello again!
I am working on a project for a few days,and it seems i've ended up in a dead end just when i was about to finish it.Here's is the code so i can explain my problem.

#include <iostream>
#include <fstream>
#include <cstring>
#include <vector>
#include <cstdlib>
using namespace std;


void saveTofile (vector <string> v);
int readFromFile (vector <string> &v , int &i,string line);
void show (vector <string> v);


int main()
{
    ofstream myfile ("data.txt");
    vector <string> v;
    string line;
    int i = 1 ;
    while(line != ":q")
    {
        cout << i << "> ";
        getline (cin , line);                                            
        if ( line.at(0) == ':' )
        {
            if ( line.at(1) == 'c' )
            {
                v.clear();                                                  //clears vector
                i = 1;
            }
            else if ( line.at(1) == 's' )
            {
                show(v);                                                    //shows vector
            }
            else if ( line.at(1) == 'd' )
            {                               
                int k ;
                k = atoi(line.substr(3).c_str());                            // char--> int
                v.erase( v.begin() + (i+1) , v.begin()+ (i+k) ) ;            //erases the vector
                i++;
            }
            else if ( line.at(1) == 'w')
            {
                 saveTofile (v);                                             //saves the vector
            }
            else if (isdigit(line.at(1) ) )
            {
                 i = atoi (line.substr(1).c_str()) ;                         //jumps to line given by the user
            }
            else if (line.at(1) == 'i')
            {
                 readFromFile (v,i,line);                                    //inserts lines from txt file
            }
            else if ( line.at(1) == 'a')
            {
                 i=v.size();                                                 //changes current line to last line
            }         
        } 
        else
        {
             v.push_back(line);                                        //inserts line in vector
             i++;
        }

    }
    system("PAUSE");
    return 0;
}

//function for saving vector to file
void saveTofile (vector <string> v)
{
         ofstream myfile ("data.txt");
         for (int n = 0 ; n < v.size(); n++)
         {
               myfile << v[n] << endl;
         }
}

//function for reading file to vector
int readFromFile (vector <string> &v,int &i , string line)
{                                                      
     ifstream myfile (line.substr(3).c_str());
     char s[256];
     int oldVsize = v.size();
     while (!myfile.eof()) 
     {
           if (i<=oldVsize)
           {
                myfile.getline(s,256);
                v.insert (v.begin()+i , oldVsize-i,s);  
                i++;        
           } 
           else
           {  
               myfile.getline(s,256);
               v.push_back (s);
           }
     }     
     i=v.size();
     myfile.close(); 
}

//function for showing vector
void show( vector <string> v)                                        
{
    for(int i=0; i < v.size(); i++)
    {
        cout << i + 1 << "> " << v[i] << endl;
    }
}

The problem is with the function readFromFile,where i couldn't do anything better than that...
The description of the command is: (:i filename) to insert the lines of the file.If current line is i and the filename has m lines,then the lines from n to n+m-1 contain the filename data, while the previous contents of the lines n,n+1,n+2,.. , have moved to n+m,n+m+1,n+m+2.After the completion of the function,current line should be line (n+m).
I should point out that we suppose the commands are always correct,so there will be no need to check it.The commands also don't have to be saved in the vector.

[Galik]

First off you should not loop on myfile.eof(). The reason being that EOF will not be flagged until *after* the read has failed. So you will be including one line of duff data.

Consider this file loop example:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

#include <fstream> #include <iostream> #include <string> #include <vector> int main() { std::vector<std::string> v; v.push_back("Line A"); // position 0 v.push_back("Line B"); // position 1 v.push_back("Line C"); // position 2 v.push_back("Line D"); // position 3 - insert here v.push_back("Line E"); // position 4 int i = 3; // insert position std::ifstream ifs("input.txt"); // file to insert std::string line; while(std::getline(ifs, line)) { // only gets here if line is valid! // insert at position i in vector v.insert(v.begin() + i, line); ++i; // next position } // Display the result for(size_t i = 0; i < v.size(); ++i) { std::cout << v[i] << '\n'; } }

Line A Line B Line C Insert 1 Insert 2 Insert 3 Line D Line E

That might be the kind of thing you need. Note that I put the std::getline() function inside the while() condition.

[rotundjere]

It's not what i exactly needed,but you help a lot!I changed the while() a bit and got the results i needed.Thanks a lot man!