Help, problem with struct and vector!

[luspank13]

Ok thanks a lot:) But the thing is that i can't check if it works because as i said in an earlier comment i can only type in one name, second name and town. When i press enter to enter the next name etc, the program closes and gives me a list with only one row. It is supposed to end when hitting control-D.

[j3Rz8vqX]

Interpreting the last several posts:
Quoted from NT3:

    for (int i = 0; i < iterations; ++i) {
        cout << "Please type in first name, last name and your hometown: ";
        input(v);
    }

Assign iteration a value equal to the number of inputs you would like to enter.

Quote from NT3:

//In that case, use std::random_shuffle from algorithm:
    std::random_shuffle(v.begin(), v.end());
    std::cout << "Your list: " << std::endl;
    print(v);

Use the above logic to shuffle your vector before outputting it.

Quote from Catfish666:

//so somewhere we should call:
std::srand(std::time(NULL));

Ensure to declare this before std::random_shuffle, though it may not be necessary.

Possibly something like this (credit to the above appropriate programmers):

    std::srand(std::time(NULL));
    for (int i = 0; i < iterations; ++i) {
        cout << "Please type in first name, last name and your hometown: ";
        input(v);
    }
    std::random_shuffle(v.begin(), v.end());
    std::cout << "Your list: " << std::endl;
    print(v);

I believe srand requires the cstdlib.

#incldue <cstdlib> 

As for your escape sequence, possibly parse your inputs against "Ctrl -D"?
Ctrl-D is character 'EOT'.

When should the user be able to exit data entry process? (first, last, town, all, or possibly during the control loop)

Maybe a do-while loop instead of a for-loop if you want a user control loop?

char choice;
do
{
    //process code here;
    //may need a cin.get() here if cin is flagged.
    choice=cin.get();
}while(choice!='EOT');

Possible end result:

    char choice;
    std::srand(std::time(NULL));
    do
    {
        cout << "Please type in first name, last name and your hometown: ";
        input(v);
        //cin.get(); //may need to clear buffer in cin
        choice=cin.get();
    }while(choice!='EOT');
    std::random_shuffle(v.begin(), v.end());
    std::cout << "Your list: " << std::endl;
    print(v);

There are lots of design possibility.

References to Ctrl-D ASCII:
http://www.asciitable.com/
http://www.unix-manuals.com/refs/misc/ascii-table.html

Reference to cin.get():
http://www.cplusplus.com/reference/istream/istream/get/

Note: I have not tested any of the above code, again credits to NT3 and Catfish666.

[luspank13]

Hmm, i can't get the random generator to work, anyone tried it? I can still only put one name in and then it closes the program. I want to be able to enter like 20 names or so:)

#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>
using namespace std;

struct name
{
  string first_name;
  string last_name;
  string town;
};

void input(vector<name>&v);
void print(const vector<name> &);

int main()
{
  
  vector<name>v;
  cout<<"Please type in first name, last name and your hometown: ";
  input(v);
  random_shuffle(v.begin(), v.end());
  cout<<"Your list:"<<endl;
    print(v);

  return 0;
}

void input(vector<name> &v)
{
  name newName;
  cin>>newName.first_name >> newName.last_name >> newName.town;
  v.push_back(newName);
}

void print(const vector<name> &v)
{
  cout<<"Startlist: "<<endl;
  cout<<"Startnumber    Firstname      Secondname        Town"<<endl;
  for(int i=0; i<v.size(); ++i){
    cout<<(i+1)<<setw(20)<<v[i].first_name<<setw(9)<<" "<<v[i].last_name<<setw(8)<< " "<<v[i].town<<endl<<endl;
  }

}

[JLBorges]

> I can still only put one name in and then it closes the program.
> I want to be able to enter like 20 names or so:)

Put this in a loop:

  cout<<"Please type in first name, last name and your hometown: ";
  input(v);

[luspank13]

Ok i get it quite to work :) But i don't really know how many i should type in. What should i use instead of i<list?

int list=20;
  vector<name>v;
  for(int i=0; i<list; ++i){

int main()
{
  
  int list=20;
  vector<name>v;
  for(int i=0; i<list; ++i){
  cout<<"Please type in first name, last name and your hometown: ";
  input(v);
  }
  random_shuffle(v.begin(), v.end());
  cout<<"Your list:"<<endl;
    print(v);

  return 0;
}

[JLBorges]

> What should i use instead of i<list?

// returns false on eof
// (for eof, type in CTRL+D on Unix or Unix clones, CTRL+Z on Windows)
// returns true after adding element to vector otherwise
bool input( vector<name> &v )
{
    name newName;
    if( cin>>newName.first_name >> newName.last_name >> newName.town )
    {
        v.push_back(newName);
        return true ; 
    }
    return false ;
}

And then, in main(), instead of the for loop:

vector<name>v;

do cout<<"Please type in first name, last name and your hometown: ";
while( input(v) ) ;

[luspank13]

Oh thanks!:D Works great now!

[luspank13]

But it still won't give me different lists on cout:D

The program should generate different start lists for each cout, and even with the same participants.

hmm anyone? Otherwise it works great!

[yulingo]

You need to seed the random number generator at the beginning of main(), as shown above:
std::srand(std::time(NULL));.

Otherwise, the random number generator will initialize the same exact way every time and produce the same sequence.

[JLBorges]

> The program should generate different start lists for each cout, and even with the same participants.

http://www.cplusplus.com/forum/beginner/119550/#msg656957
http://www.cplusplus.com/forum/beginner/119550/#msg656959