Question

Possible Duplicate:
rand function returns same values when called within a single function c++

Why is rand() generating the same number?

die.h

#ifndef DIE_H
#define DIE_H


class Die
{
private:
    int number;
public:
    Die(){number=0;}
    void roll();
    int getNumber()const{return number;}
    void printValue();
};

#endif

die.cpp

#include"die.h"
#include<iostream>
#include<time.h>
using namespace std;

void Die::roll()
{
    srand(static_cast<int>(time(0)));
    number=1+rand()%6;
}

void Die::printValue()
{
    cout<<number<<endl;
}

main.cpp

#include"die.h"
#include<iostream>
using namespace std;

int main()
{
    Die d;
    d.roll();
    d.printValue();
    d.roll();
    d.printValue();
    d.roll();
    d.printValue();
}

Answer 1

Your calls to die.roll() are so close together that time(0) is actually returning the same value every time, and, thus, your rand seed is the same for each call to .roll().

Try calling srand(static_cast<int>(time(0))); once (and only once) outside of .roll() (like in the Die constructor or main()).