Program for Random numbers having a bit of trouble.

[radskate360]

HI,

I have been working on this program for a bit now and having a little bit of trouble, I have got most of it but still a few stumbles.

Here is the Directions:

Write a program that will generate an unknown (between 93 and 139) count of random numbers whose values fall between 147 and 206. Calculate the average to 2 decimal places and standard deviation to 3 decimals. On the monitor display only the count of numbers, the mean, and the standard deviation. Then after you have displayed alll of that information list them again in 5 columns in order from high to low and then have skipped two spaces.

I just chose lower numbers than required for now to see if I can figure this out any easier.

So far I can get everything to work but coming out with strange numbers for standard deviation and average.

std deviation is sqrt of (                    2                                   2
                                    sum of num                  (sum of num)
                                  _____________     ___    _____________
                                                                                     2
                                       count                               count

this is what i have so far:

srand((unsigned int) time (NULL));
    int first, second;
    int high, low, high2, low2;
    int number, number2;  
    int total, total2, overall;
    double average, deviation;
    high = 3;
    low = 2;
    high2 = 10;
    low2 = 5;


  for (first=0; first<1; first++) 
  {
      number = rand()%(high-low+1)+low;
  }

      for (second=0; second < number; second++)
          {
               number2 = rand()%(high2-low2+1)+low2;
               total = number2 * number2;
               total2 = total2 + number2;
               overall = overall + total;
               cout << number2 << endl;


          }
   average = total2 / second;
   deviation = sqrt((overall/second) - ((total2 * total2)/(second * second)));

   cout << setprecision ( 2 ) << average << endl;
   cout << setprecision ( 3 ) << deviation << endl;

Thank you all for any help you can give.

Radskate360

[iamthwee]

try writing down the s.d on paper for a few numbers.

Then walk through your program and place a few couts to see where it may be going wrong.

[Narue]

Strange values usually means you didn't initialize a variable somewhere. For example, you don't initialize total2 when it should be set to 0 for an accurate sum.

[anujsharma]

hi can anyone tell me how to generate random number within certain limit as in between 10 to 20 etc .please help me
Thanks
anuj

[ArkM]

10..20 or 11..19 or what else? [0,n) - 0, 1, ... n-1 :

rand() % n