Functions with C++

[xcodeandre]

#include <iostream>
#include <math.h>
#include <string>
using namespace std;
int golf();
int hotel();

int main(){
hotel();
}
int golf(){
srand(time(NULL));
rand() % 6 + 1;
}
int hotel(){
int r1;
int r2;
int counter = 1;
while(counter > 0){
if(r1 != r2){
cout << counter << endl;
counter++;
}
golf();
}
return hotel();
}




I'd like to create a function that randomly rolls two dice and outputs how many times it takes for both dice to equal the same number. This is my attempt

[kbw]

Call srand() once.
Call rand() each time you want a random number.

[deleted account xyzzy]

PLEASE learn to use code tags, they make reading and commenting on source code MUCH easier.

http://www.cplusplus.com/articles/jEywvCM9/

Hint: you can edit your post and add code tags.

[jonnin]

ok that is an exciting first crack :)

srand is for C random numbers and is not recommended, c++ uses random, but you can read that tutorial later. Just be aware not to use it after you get past beginner problems.

c++ uses <cmath> not <math.h>. The difference is minor but it matters later on.

#include <iostream>
#include <math.h>
#include <string>
using namespace std;
int golf();
int hotel();

int main()
{
  srand(time(NULL)); //moved
  //hotel();  disabled not sure what its supposed to do.
  int value = 0;
  value = golf(); //like this  store the value created in golf into a variable to use later. 
  cout << value << endl;  //show the random number 
  //or this
   cout <<golf() << endl; //the random number is printed but lost, you can't get it back, but you can see it. 
}

int golf()
{
  return (rand() % 6 + 1); //returns the value now.
}

int hotel()
{
  int r1;
  int r2;
  int counter = 1;
  while(counter > 0)
{
  if(r1 != r2)
  {
      cout << counter++ << endl;
      //counter++;  //combined above
}
   //golf(); //this does nothing.  should be like what I did in main, x=golf(); format
}
   //return hotel(); //this is wrong but may compile.  what result do you want to return? 
   //the function wants an integer result, but what integer, and what does it mean?
}

[keskiverto]

rolls two dice and outputs how many times it takes for both dice to equal

count = 0
REPEAT
  red  = roll()
  blue = roll()
  ++count
  WHILE red not blue
show count

[lastchance]

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

int numberUntilSame()
{
   return 1 + ( ( rand() - rand() ) % 6 ? numberUntilSame() : 0 );
}

int main()
{
   srand( time( 0 ) );
   cout << "Number of pairs thrown until the same = " << numberUntilSame() << '\n';
}

Or let's see how good rand() is. (Average here should be 6.0)

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

int numberUntilSame()
{
   return 1 + ( ( rand() - rand() ) % 6 ? numberUntilSame() : 0 );
}

int main()
{
   srand( time( 0 ) );
   const int N = 10000;
   int sum = 0;
   for ( int i = 0; i < N; i++ ) sum += numberUntilSame();
   
   cout << "Average number until the same = " << (double)sum / N << '\n';
}