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Re: [Dev-C++] die rolling problem
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From: Per W. <pw...@ia...> - 2004-07-06 20:58:32
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I don't know what you need face_1 ... face_6 for.
int faces[6] is an array of 6 integers - same as the number of sides on a
dice. You start by setting each value to zero.
Whenever you roll a dice, you get an asnwer between 1 and 6. If you get
the value 1, you increment faces[1-1]. If you get the dice value 2, you
increment faces[2-1] and so on.
Let's assume that you do 100 rolls. When your for loop is finished, you
might write something like:
printf("Number of ones: %d.\n",faces[0]);
...
printf("Number of sixes: is %d.\n",faces[5]);
and get the output:
Number of ones: 17
...
Number of sixes: 16
There is no need for a second loop, other than at the end of the program
if you want to emit the percentage (or total count) you got of each of the
six sides of the dice. The same loop that throws the dice 'roll' number of
times will at the same time count the number of occurrences of the
different sides of the dice.
/Per W
On Tue, 6 Jul 2004, PETER CAMPOS wrote:
> per, i follow your logic up until:
> "Maybe you somewhere in the program - in your first fir loop, where you
> >throw your dices - should use the first array and do:
> > faces[face-1]++;
> >to count up number on ones, twoes... while you are busy rolling the
> >dices."
>
> how would i implement the array into counting how many ties a number comes up while at the same time not incrementing the number of rolls? i understand that faces[0]=faces[1-1], for example but i don't know how to use it properly. i tried the do..while loop below but i know taht i am not using it properly.
> thanx peter
>
> #include <iostream>
> #include <ctime>
> #include <cstdlib>
> using namespace std;
> int main()
> {
> int faces[6] = {0};
> int face_1, face_2, face_3, face_4, face_5, face_6;
> face_1 = faces[0];
> face_2 = faces[1];
> face_3 = faces[2];
> face_4 = faces[3];
> face_5 = faces[4];
> face_6 = faces[5];
>
> int rolls;
> cout << "how many times do you want to roll the die? "; //how many times to roll die
> cin >> rolls;
>
> srand(time(0));
> int face;
> for(int i= 0; i < rolls; i++){
> do{
> face= rand();
> face= 1+ face%6;
> cout << "the die has rolled a:" << face << endl;
> }while (faces[face-1]++);
>
>
> }
>
>
>
> return 0;
>
> }
>
>
> ---------- Original Message ----------------------------------
> From: Per Westermark <pw...@ia...>
> Date: Tue, 6 Jul 2004 20:11:23 +0200 (CEST)
>
> >
> >
> >Let's see now:
> >
> >You have one array
> > int faces[6]
> >which you don't seem to use anywhere in your program - other than to
> >assign uninitialized variables (face_1) to index position 0:
> > int face_1;
> > faces[0] = face_1;
> >Maybe you wanted to write:
> > face_1 = faces[0];
> >since the goal should be that faces[0] stored the count of ones you got
> >from all the rolls?
> >
> >Then you have one other array
> > int die[6] = {1,2,3,4,5,6};
> >that is most definitely not needed.
> >
> >Maybe you somewhere in the program - in your first fir loop, where you
> >throw your dices - should use the first array and do:
> > faces[face-1]++;
> >to count up number on ones, twoes... while you are busy rolling the
> >dices.
> >
> >Aftwerards, faces[0] would be number of times you got a one. faces[1]
> >would be the number of times you got a two etc and faces[0] + faces[1] +
> >... + faces[5] would be the total number of times you rolled the dice,
> >i.e. the same as the value rolls. 100*faces[0] / rolls would then be
> >number of times you got a one.
> >
> >Since faces[0] .. faces[5] would then contain counted values, you never
> >need a second for loop in the program for building statistics. You could
> >however use the second loop to emit your 6 percentages: probability of
> >getting a one, probability of getting a two...
> >
> >I think I recommended you once before to always build your programs with
> >the setting -Wall active. That would have generated a warning about face_1
> >being used without having been initialized. Always let the compiler
> >generate as much warnings as possible. For a biginning programmer, all
> >warnings are useful. If you think a warning is stupid, you should know
> >specifically why the compiler emitted the warning, and why the warning
> >isn't apropriate for your specific program. When you are ready to keep a 5
> >minute presentation in front of your class about a specific warning, then
> >you have enough knowledge to decide when to ignore warnings of that
> >specific type. Before that, you should treat warnings as errors, and make
> >sure your code compiles with zero warnings at the highest warning level
> >(-Wall).
> >
> >/Per W
> >
> >On Tue, 6 Jul 2004, PETER CAMPOS wrote:
> >
> >> Remarks by per are below..i attempted to set up a counter to count the number of times a die comes up and from that calculate the percentage. so far i get very small negative numbers...
> >> am i going in the correct direction?
> >> panos/peter
> >>
> >> #include <iostream>
> >> #include <ctime>
> >> #include <cstdlib>
> >> using namespace std;
> >> int main()
> >> {
> >>
> >> int rolls;
> >> cout << "how many times do you want to roll the die? "; //how many times to roll die
> >> cin >> rolls; //user input
> >> int faces[6] = {0}; //array for storage of faces of die.
> >> //used later to calculate percentage
> >> int face;
> >> srand(time(0)); //user wants new random #'s generated each time
> >> int face_per;
> >>
> >> int die[6] = {1,2,3,4,5,6};
> >> for(int i = 0; i < rolls; i++){
> >> face = rand();
> >> face = 1+ face%6;
> >> cout << "the die has rolled: " << face << endl;
> >> }
> >>
> >> int face_1;
> >> int face_1_occur;
> >> faces[0] = face_1;
> >> face_1_occur = 0;
> >> for(int i =0; i<rolls; i++){
> >> face_1_occur = face_1 + 1; //counter for face 1
> >>
> >> double prob_1 = face_1_occur * 100/rolls;
> >> cout << "the probability to roll a 1 is" << prob_1 << endl;
> >> }
> >> return 0;
> >> }
> >>
> >> 1) You don't store an infinite number of dice values - no need to. Just
> >> emit the value for each throw on the fly. Then keep 6 counters - one for
> >> each of the 6 faces of the dice.
> >>
> >> 2) Emit the 6 counters. Percentage is just # of occurences * 100 / total
> >> throws.
> >>
> >> 3) If the values you put into an array are in range 1-6, of course the
> >> values stay in that range. However, normally when counting number of
> >> times you get a one, a two etc, you store that in an array with index 0 to
> >> 5, since all arrays in C and C++ starts with index zero.
> >>
> >> /Per W
> >
> >
>
>
>
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