testdice.cpp

C++&datastructure书籍源码,以前外教提供现在与大家共享

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

// simulate rolling two dice to obtain all possible sums
// repeat the "experiment" specified number of times
// Owen Astrachan, 8/9/94, modified 6/9/95, 4/20/99

double RollTest(int target,int experiments);

int main()
{
    int numTimes;                       // for one trial
    long totalRolls;                    // accumulate for all trials
    int k;
    
    numTimes = PromptRange("number of 'trials' ",100,20000);

    totalRolls = 0; 
    for(k=2; k <= 12; k++)
    {   cout << k << "\t" << RollTest(k,numTimes) << endl;
    }

    return 0;
}

double RollTest(int target, int trials)
// precondition: 2 <= target <= 12, 0 < trials
// postcondition: returns average # of rolls needed to obtain target
//                trying 'trials' times
{
    Dice d1(6);
    Dice d2(6);
    
    int total = 0;
    int k;
    for(k=0; k < trials; k++)
    {   int numRolls = 1;                       //first time through loop is 1 roll
        while (d1.Roll() + d2.Roll() != target)
        {   numRolls += 1;
        }
        total += numRolls;
    }   
    return double(total)/trials;
}