How to add in a random seed. with desired input

[JulyZerg]

hi i am doing a program that requires me to input a random seed (already chosen) and input a maximum of 5 friends to text, randomly choose one and output the chosen name and the names that did not get chosen. i am trying to hard code the sites preset input, but i dont know how to add in the seed generator, so the program could work without hard coding it. please help me!

the first set of inputs is:
21(seed)
adam
bill
cat
damion
edward.

//and cat would be the chosen friend.


first one is my attempt to hard code the site, second is without the seed generator.

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;

string get_random_name(string arr[], int& nums)
{
    int num = rand() % nums;
    string name = arr[num];
    arr[num] = arr[nums - 1];
    --nums;
    return name;


}

int main()
{
    srand(time(NULL));
    string num_names[6];
    int num_of_names = 5;
    int seed;
    int N = 6;

    cout << "== Who Should I Text? ==" << endl;
    cout << "Enter seed" << endl;
    cin >> seed;

    if (seed == 21)
    {

    for (int counter = 0; counter < num_of_names; counter++)
    {
        cout << "Enter friend " << counter << endl;
        cin >> num_names[counter];


    }
    cout << "You should text: " << get_random_name(num_names, num_of_names) << endl;

        cout << "These other friends didn't make the cut:" << endl;

            for (int i = 0; i < num_of_names; ++i)
            {
                cout << num_names[i] << endl;
            }

    return 0;
    }

    else if (seed == 42)
    {
        for (int counter = 0; counter < num_of_names; counter++)
    {
        cout << "Enter friend " << counter << endl;
        cin >> num_names[counter];


    }
    cout << "You should text: " << get_random_name(num_names, num_of_names) << endl;

        cout << "These other friends didn't make the cut:" << endl;

            for (int i = 0; i < num_of_names; ++i)
            {
                cout << num_names[i] << endl;
            }

    return 0;

    }

    else if (seed == 101)
    {
        for (int counter = 0; counter < num_of_names; counter++)
    {
        cout << "Enter friend " << counter << endl;
        cin >> num_names[counter];


    }
    cout << "You should text: " << get_random_name(num_names, num_of_names) << endl;

        cout << "These other friends didn't make the cut:" << endl;

            for (int i = 0; i < num_of_names; ++i)
            {
                cout << num_names[i] << endl;
            }

    return 0;

    }
    return 0;

}

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;

string get_random_name(string arr[], int& nums)
{
    int num = rand() % nums;
    string name = arr[num];
    arr[num] = arr[nums - 1];
    --nums;
    return name;


}

int main()
{
    srand(time(NULL));
    string num_names[6];
    int num_of_names;
    int N = 6;

    cout << "== Who Should I Text? ==" << endl;
    cout << "Enter seed" << endl;
    cin >> num_of_names;

    for (int counter = 0; counter < num_of_names; counter++)
    {
        cout << "Enter friend " << counter << endl;
        cin >> num_names[counter];
    }

    cout << "You should text: " << get_random_name(num_names, num_of_names) << endl;

    cout << "These other friends didn't make the cut:" << endl;

    for (int i = 0; i < num_of_names; ++i)
    {
        cout << num_names[i] << endl;
    }
    return 0;

}

[helios]

Wait, I don't understand. You tell the user "Enter seed" but then store the input in a variable that limits the number of friends that can be entered. Is the for condition wrong, or are you missing an input variable?

[j3Rz8vqX]

What is the significance of 21, 42, and 101?

Edit:
Generally a seed is implanted into the srand function to control randomness.

srand(seed);

High possibility I am misinterpreting something here.

[JulyZerg]

this is the question: Write a program that randomly determines whom the user should send a text message to. Allow the user to enter five friends that will be used for the selection.. . .

this is the givin input that my program will be tested with: Program Input
Standard Input
21
Adam
Bill
Cat
Damion
Edward
Program Output
== Who Should I Text? ==
Enter seed
Enter friend 0
Enter friend 1
Enter friend 2
Enter friend 3
Enter friend 4
You should text: Cat
These other friends didn't make the cut:
Adam
Bill
Damion
Edward

[j3Rz8vqX]

My assumption is that you would like to manually control the seed of rand().
So when you prompt for the seed and a value of 21 is entered, it would produce Cat as the chosen seed.

Based on the shorten code:

Declare an integer named seed.
Move srand below your prompt for the seed. And modify it to be:
srand(seed);

Then clean up your remaining code; you should be okay.

Should work.

[JulyZerg]

ok this is what i have come up with. this code allows me to input friends but it gets a runtime error after the 5th name inputted. what can i do so it can work properly?

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;

string get_random_name(string arr[], int& nums)
{
    int num = rand() % nums;
    string name = arr[num];
    arr[num] = arr[nums - 1];
    --nums;
    return name;


}

int main()
{
    srand(time(NULL));
    string num_names[5];
    int num_of_names = 0;
    int seed;
    int N = 5;

    cout << "== Who Should I Text? ==" << endl;
    cout << "Enter seed" << endl;
    cin >> seed;

	srand(seed);

    while (std::cout << "Enter friend " << num_of_names << endl,
            std::cin  >> num_names[num_of_names])
          {
                ++num_of_names;
          }


    cout << "You should text: " << get_random_name(num_names, num_of_names) << endl;

    cout << "These other friends didn't make the cut:" << endl;

    for (int i = 0; i < num_of_names; ++i)
    {
        cout << num_names[i] << endl;
    }
    return 0;

}

[j3Rz8vqX]

Eh???!!

Of course it would, haha.

Okay, sorry about that.

Your while loop is incorrectly used/implemented.

Stick with your for-loop and set num_of_names equal to 5(where you declared/initialized it).

Edit:
Also remove your variable N, it isn't being used and

srand(time(NULL));

since you're declaring it below.

Edit #2:
You don't need

std::

in front of

cout

since you've included

using namespace std;

.

If you decide you really want to use a while loop, below has the design/examples:
http://www.cplusplus.com/doc/tutorial/control/

[JulyZerg]

ok it worked, but it scrambles up the last two names, or all the names, in the outputted names. why would that happened, only 1 of the 3 test cases is correct...

[JulyZerg]

this is the new code.

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;

string get_random_name(string arr[], int& nums)
{
    int num = rand() % nums;
    string name = arr[num];
    arr[num] = arr[nums - 1];
    --nums;
    return name;


}

int main()
{
    srand(time(NULL));
    string num_names[5];
    int num_of_names = 5;
    int seed;
    int N = 5;

    cout << "== Who Should I Text? ==" << endl;
    cout << "Enter seed" << endl;
    cin >> seed;

	srand(seed);

    for(int i = 0; i < num_of_names; i++)
    {
        cout << "Enter friend " << i << endl;
        cin >> num_names[i];

    }

    cout << "You should text: " << get_random_name(num_names, num_of_names) << endl;

    cout << "These other friends didn't make the cut:" << endl;

    for (int i = 0; i < num_of_names; ++i)
    {
        cout << num_names[i] << endl;
    }
    return 0;

}

[j3Rz8vqX]

Since you've already done a lot, maybe something like this:

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;

string get_random_name(string arr[], int& nums)
{
    int num = rand() % nums;
    string name = arr[num];
    arr[num] = arr[nums - 1];
    --nums;
    return name;


}

int main()
{
    //srand(time(NULL));//Commented out for other intended uses below
    string num_names[6];
    int num_of_names=5;//Modified num_of_names to be 5
    int seed = 0;//Added seed integer
    //int N = 6;//Commented out useless/unused variable

    cout << "== Who Should I Text? ==" << endl;
    cout << "Enter seed" << endl;
    cin >> seed;//Modified data entry to reflect actual seed

    for (int counter = 0; counter < num_of_names; counter++)
    {
        cout << "Enter friend " << counter << endl;
        cin >> num_names[counter];
    }

    srand(seed);//call the srand function with seed instead of time, and after seed was declared.
    cout << "You should text: " << get_random_name(num_names, num_of_names) << endl;

    cout << "These other friends didn't make the cut:" << endl;

    for (int i = 0; i < num_of_names; ++i)
    {
        cout << num_names[i] << endl;
    }
    return 0;

}

Try it.

Have fun.

Also what are you other test cases.

Given: 21 = Cat, ? = ?. ? = ?.

[JulyZerg]

the same thing happens with the above code, and the other two test cases are, 42 = Dave, 101 = Lay

[JulyZerg]

oh and the only one that works is 101 = Lay.

[j3Rz8vqX]

My psychic powers are not enabling me to project the test data contents to my device.

Sorry insufficient data. =D

[JulyZerg]

test case 1:

21
Adam
Bill
Cat
Damion
Edward

test case 2:

42
Dave
Bernard
Fred
Edna
Sid

test case 3:

101
Fastow
Skilling
McMahon
Lay
Watkins

[j3Rz8vqX]

As you've stated, I got 42 = Dave, and 101 = Lay.

What were my goals?

Who was I suppose to receive from those values?

[AbstractionAnon]

I tried your program with several test cases and it seemed to work for me.

Not sure what you meant by "42 = Dave, 101 = Lay"

[JulyZerg]

i mean the list of names that did not get picked.

the first test case should output:
adam
bill
damion
edward

second:
Bernard
fred
edna
sid

the last one is correct.

[AbstractionAnon]

I don't know that I can duplicate your results. Our random number generators are likely different unless we're using the same run-time library.

[JulyZerg]

hmm ok, i guess this will go finished/ but unfinished. :/ good thing i ahve a good grade in the class.

[j3Rz8vqX]

If the names that did not get pick are incorrect, then maybe we're approaching the rebuilding of the non selected names incorrectly.

Possibly something in the function (get_random_name).

arr[num] = arr[nums - 1];

The above code swaps:
-The person at the index of num(our random) with the person at the index of nums-1(your maximum number of people minus one: the last person)

Maybe instead of swapping the missing with the last, we should implement a design to shuffle all of the remaining folks down a notch?

Do you need help with that too? or do you've got it?