How do I seed the random number generator with the current time, display header and assign random birth dates to X amount of people (C++)

Question

I'm working on an assignment where I have to create a program that:

1. Ask user for their name
2. Prompts the user for # of voters
3. Store user entered value
4. Report errors if the user enters a negative number or a character
5. seed the random number generator with the current time

6. display header for (voterCount = 0; voterCount < numVoters; voter++)

7. use random number generator to:

   generate bYear (restricted between 1900 and 2000)

   generate bMonth

   generate bDay (limit 1 and 31)

I have the first 4 down:

#include <iostream>
#include <cstdlib>
#include <time.h>

using namespace std;

int main()
{

    int  numVoters;
    char name[35]; // Variable that stores "Name" of user added max char to be 25
    const int MIN_MONTH = 1;
    const int MAX_MONTH = 12;
    int bMonth;


    cout << "Please enter your first name: ";
    cin.getline(name,35); // used getline because without getline I kept getting a single char

    cout << "Hello " << name << endl;
    cout << "Please enter amount of voters: ";
    cin  >> numVoters;
    while (numVoters > 0)
    {
        cout << "You entered: " <<numVoters << endl;
    }
        cout << "ERROR! ERROR! WRONG DATA TYPE PLEASE RUN THE PROGRAM 
        AGAIN";

    return 0;

    }

I don't know what to do next I've tried to continue by using what I see online but when I do I get a never-ending loop of # of voters

#include < iostream > 
#include < cstdlib > 
#include < time.h >

  using namespace std;

int main() {

  int numVoters;
  char name[35]; // Variable that stores "Name" of user added max char to be 25
  const int MIN_MONTH = 1;
  const int MAX_MONTH = 12;
  int bMonth;

  cout << "Please enter your first name: ";
  cin.getline(name, 35); // used getline because without getline I kept getting a single char

  cout << "Hello " << name << endl;
  cout << "Please enter amount of voters: ";
  cin >> numVoters;
  while (numVoters > 0) {
    cout << "You entered: " << numVoters << endl;
  }
  cout << "ERROR! ERROR! WRONG DATA TYPE PLEASE RUN THE PROGRAM AGAIN";

  unsigned seed = time(0); // gets current computer time
  srand(seed); // seeds the random number gen

  for (numVoters = 0; numVoters < 0; numVoters++)

  {

    bMonth = rand() % (MAX_MONTH - MIN_MONTH + 1) + MIN_MONTH;
    cout << "Random month: " << bMonth << endl;
  }
  return 0;

}

Help with #5-7

Algorithm.

Answer 1

while (numVoters > 0)
{
    cout << "You entered: " <<numVoters << endl;
}
    cout << "ERROR! ERROR! WRONG DATA TYPE PLEASE RUN THE PROGRAM 
    AGAIN";

The code above is saying, that as long as numVoters is more than 0, endlessly output the numVoters. What you need is an if else statement, as you want to say if the number of voters is above 0, output the number of voters and continue to do tasks 5,6, and 7. Otherwise, you want to output error. In pseudocode:

if (numVoters > 0) {
    output numVoters
    do tasks 5,6,7
}
else {
    output error
    return 0
}

Or you could just instead do if numVoters is equal or less than 0 output error and quit the program. Place code for task 5,6,7 after the if loop, so it executes if there is no error only:

if (numVoters =< 0) { 
    output error
    return 0
}
//code for 5,6,7 after and outside of the if loop

Also (voterCount = 0; voterCount < numVoters; voter++) , seems to me to be (int voterCount = 0; voterCount < numVoters; voterCount++) .

In general, I think you misunderstand while and for loops. You should read up on them to understand where you went wrong.

Answer 2

As someone stated your while loop is infinite if a valid value is given

gettimeofday() information may be found here http://man7.org/linux/man-pages/man2/gettimeofday.2.html

rand_r() information can be found here https://linux.die.net/man/3/rand_r

Keep these handy, these are good references for future coursework!

#include <iostream>
#include <cstdlib>
#include <time.h>
#include <sys/time.h>

using namespace std;
const int MAX_LENGTH = 35;
const int MAX_MONTH = 12;
const int MAX_DAY = 31;
const int MAX_YEAR = 100;
void getName(char name []);
void sayName(char name []);
int getVoters();

int main() {

  int numVoters;
  char name[MAX_LENGTH]; // Variable that stores "Name" of user added max char to be 25

  struct timeval tv;

  getName(name);
  sayName(name);
  numVoters = getVoters();

  unsigned int seed = time(0); // gets current computer time
  gettimeofday(&tv,NULL);

  int day = 0;
  int month = 0;
  int year = 0;
  int voterNumber = 1;
  for (int i = numVoters;i > 0;i--)
  {
    seed = (unsigned int)((tv.tv_sec+tv.tv_usec)*i);
    month = rand_r(&seed)%MAX_MONTH + 1;
    day = rand_r(&seed)%MAX_DAY + 1;
    year = rand_r(&seed)%(MAX_YEAR+1) + 1900;

    cout<<"Voter #"<<voterNumber++<<" DD/MM/YYY DOB: ";
    cout<<day<<"/"<<month<<"/"<<year<<endl;
  }
  return 0;

}



void getName(char name[])
{
    cout<<"Please enter your first name: ";
    cin.getline(name,35);
}

void sayName(char name [])
{
    cout<<"Hello "<<name<<endl;
}

int getVoters()
{
    int voters = -1;
    cout<<"Please enter amount of voters: ";
    cin>>voters;

    if(voters < 0)
    {
        cout << "ERROR! ERROR! WRONG DATA TYPE PLEASE RUN THE PROGRAM AGAIN";
    }
    else if(voters == 0)
    {
        cout<<"Either you entered 0 or an invalid date type";
    }
    else
    {
        cout << "You entered: " << voters << endl;
    }
    return voters;

}