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Ryanbhl

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C++ help Please

Hi experts,

I have the code as following. Can anyone give an idea how to place two strings in the file into two vectors ?
Thank you very much!

*****************************************************
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include <cstring>

using namespace std;

 #define size 1000

int main()
{
             
      ofstream SaveString("strings.dat", ios::out);
      SaveString << "Test string1\n";
      SaveString << "Test string2\n";
      SaveString.close();


      ifstream Openstring("strings.dat", ios::in);
      char str;
      
      while (!Openstring.eof())
      {
            Openstring.get(str);
            cout << str;
      
      }

      Openstring.close();

/      return 0;
}
*************************************************
Avatar of rstaveley
rstaveley
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Not sure if I understood your question properly, but does this help?

--------8<--------
#include <iostream>
#include <fstream>
#include <iterator>
#include <vector>
#include <string>

int main()
{
        std::vector<std::string> v;

        // Load the vector - use push_back to grow it accordingly      
        v.push_back("Test string 1");
        v.push_back("Test string 2");

        // Load the strings into the file
        {
                std::ofstream fout("strings.dat");
                copy(v.begin(),v.end(),std::ostream_iterator<std::string>(fout,"\n"));
        }

        // Read the strings from the file
        {
                std::ifstream fin("strings.dat");
                std::string str;
                while (getline(fin,str))
                        std::cout << str << '\n';
        }
}
--------8<--------
Avatar of Ryanbhl
Ryanbhl

ASKER

Hi  rstaveley,

Thank you very much for your help.

May be I did make it clear enough. I have a file stores two strings above, now I want to read the file, take two the strings and put them into two seperate vectors.

Example:
I have two vectors : vec1, vec2
Now, I want to put "Test string 1" into "vec1" ; and "Test string 2" into "vec2" by reading them from the file.
ASKER CERTIFIED SOLUTION
Avatar of meow00
meow00

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Avatar of Ryanbhl

ASKER

Thank you meow00,

Yes, that is what I am trying to do right now.
May I ask a question ?  

******************************************************
(count%2 ==0)? vec1.push_back(temp): vec2.push_back(temp) ;
******************************************************
In the line above, what does "count%2 == 0" mean ?? I am have some confuse here. I am very glad if you can explain it to me.

Again, Thank you very much for your guide.
> (count%2 ==0)? vec1.push_back(temp): vec2.push_back(temp) ;

This is equivalent to

    if (count % 2 == 0)             /* If count is an even number */
        vec1.push_back(temp);
    else
        vec2.push_back(temp) ;

It pushes the tring alternately into one vector and then the other.
Yes, rstaveley is correct !

 "(statement) ? A : B ;" means :
  if statement is true, we execute A ;
  if statement if false, we execute B ;
--------------------------------------------
 Also,  % means the residual of the division (modulus).
 e.g.    7/3 = 2 ......1   -> 7%3 = 1
           8/2 = 4 ......0   -> 8%4 = 0
           9/5 = 1 ......4   ->  9%5 = 4
                             ^
                          This is the residual
Avatar of Ryanbhl

ASKER

Thank you rstaveley and meow00 a lot,

Now I understand a lot more and know how to use the statement:  "(statement) ? A:B . I was doubt about this before but not anymore.
I really apreciate you guys.

Ryanbhl