Hi all,
I have a file with data 300 lines. (in.txt)

I want to make a program that seperates the file in two others (out1.txt, out2.txt).
But I would like to do it with percentage.

For example,
Percentage (%): 50

and seperate the in.txt file in the middle but with random lines from the file.

A line that is in the out1.txt there is no in out2.txt


Could you help me please ?

Simple Random Selection Without Replacement From a Finite Population

1. Let [b]P[/b] be the fraction of lines to be written into the first file ( [b]P[/b] == 0.63 => 63% )

2. Read all the 300 or so lines from the input file into a [b]std::vector< std::string >[/b]

3. Let [b]N[/b] be the size of the vector (number of lines read)

4. Shuffle the contents of the vector using [b]std::random_shuffle()[/b]

5. Let [b]M[/b] be [b]P * N[/b] rounded to the nearest integer

6. Write the first [b]M[/b] lines into the first output file.

7. Write the remaining [b]N-M[/b] lines into the second output file.

Simple Random Selection Without Replacement From a Finite Population

1. Let [b]P[/b] be the fraction of lines to be written into the first file ( [b]P[/b] == 0.63 => 63% )

2. Read all the 300 or so lines from the input file into a [b]std::vector< std::string >[/b]

3. Let [b]N[/b] be the size of the vector (number of lines read)

4. Shuffle the contents of the vector using [b]std::random_shuffle()[/b]

5. Let [b]M[/b] be [b]P * N[/b] rounded to the nearest integer

6. Write the first [b]M[/b] lines into the first output file.

7. Write the remaining [b]N-M[/b] lines into the second output file.

I found the N and read all the lines but I don't understand how to do the others
:(

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


using namespace std;


void readFile(vector<string>& name_vec, string name_file);


int main()
{
       float p;
       int len;
       
       vector<string> lines;
       ifstream readLines;
       
       cout << "Fraction : ";
       cin >> p;
       
       
       readFile(lines, "in.txt");
       len = lines.size();
       
       
       
       ofstream outfile1("1.txt");
       ofstream outfile2("2.txt");
       
       
       if (!outfile1) {
        cerr << "Unable to write "  << endl;
        exit(1);
      }
      
      if (!outfile2) {
        cerr << "Unable to write "  << endl;
        exit(1);
      }
    

    
      cout <<"No Lines: "<< len << endl;
     
      cout<< lines[rand()];
     
     
     
       
       system("pause");
       return 0;
}




void readFile(vector<string>& name_vec, string name_file) 
{
    ifstream infile;
    infile.open(name_file.c_str());
    if (!infile) {
        cerr << "Unable to read " <<  name_file << endl;
        exit(1);
    }
    for (string someName; infile >> someName; ) {
        name_vec.push_back(someName);
    }
    infile.close();
}

You need to read lines (not individual strings) from the file. Use std::getline() for that.

std::string someName ;
while( std::getline( infile, someName ) )
    name_vec.push_back(someName);

See: http://www.arachnoid.com/cpptutor/student2.html

Then use std::random_suffle() to randomly shuffle the contents of the vector.
See: http://stdcxx.apache.org/doc/stdlibref/random-shuffle.html

Do not forget to seed the random number generator in main.
See: http://www.richelbilderbeek.nl/CppSrand.htm

You need to read lines (not individual strings) from the file. Use std::getline() for that.

std::string someName ;
while( std::getline( infile, someName ) )
    name_vec.push_back(someName);

See: http://www.arachnoid.com/cpptutor/student2.html

Then use std::random_suffle() to randomly shuffle the contents of the vector.
See: http://stdcxx.apache.org/doc/stdlibref/random-shuffle.html

Do not forget to seed the random number generator in main.
See: http://www.richelbilderbeek.nl/CppSrand.htm

Thanks a lot

This article has been dead for over six months. Start a new discussion instead.