Re: [Dev-C++] (no subject)

[Per W. <pw...@ia...>]

Modify rule 2 below to be system("PAUSE");

About the random generation. It is very, very wrong.

1) You say you need 6 random numbers, but you run your generation loop 49
times (1..49).

2) You never assign an random number anywyere...

Your loop contains:
temp = nums[i]; nums[i] = nums[r] = temp;

In the first assignment, nums[i] hasn't been initialized yet, so temp will
be set to an unknown value (which isn't the same as setting it to a random
value).

In the second assignment, you take temp (which has an undefined value) and
assign to the i:th and the r:th element...


I would assume that you were planning on filling the array with the values
1..49, and then perform 49 permutations to get the values 1..49 in random
order, to make sure that the 6 values you print doesn't contain any
repetition.

for (i = 1; i < 50; i++)
  nums[i] = i;
for (i = 1; i < 50; i++) {
  r = (rand() % 49) + 1;
  temp = nums[i];
  nums[i] = nums[r];
  nums[r] = temp;
}

One other thing. I think it is better to always use all elements of an
array, i.e. use index 0..48 instead of creating the array one element
larger and skip nums[0].

/Per W

On Sat, 11 Sep 2004, Scott Simontis wrote:

> Three solutions:
> 1. Run your program from a console prompt
> 2. Include cstdlib and add the line system("APUSE); before return 0
> 3. Create a useless variable and add a cin statement for it before the
> return 0
>
> --Scott Simontis--
>
>
>
> Meyer von Landenhausen wrote:
>
> > hi please take a look at the source:
> >
> > #include <ctime>
> > #include <iostream>
> > using namespace std;
> >
> > int main()
> > {
> > char buffer[3];
> > int i,r,temp;
> > int nums[50];
> >
> >
> > for(i = 1; i < 50; i++)
> >       {
> >       r = (rand() % 49) + 1;
> >       temp = nums[i]; nums[i] = nums[r] = temp;
> >       }
> >
> >
> >       cout << "Your six lucky numbers are...\n";
> >       cout << itoa(nums[1], buffer, 10) << "   ";
> >       cout << itoa(nums[2], buffer, 10) << "   ";
> >       cout << itoa(nums[3], buffer, 10) << "   ";
> >       cout << itoa(nums[4], buffer, 10) << "   ";
> >       cout << itoa(nums[5], buffer, 10) << "   ";
> >       cout << itoa(nums[6], buffer, 10) << "   ";
> >       cout << endl;
> >       return 0;
> >       }
> >
> >
> > i cant run without that win2k pro automaticly closes the apllication
> > after i ran it - what kind of code should i inserted therefore i take
> > a look first at the code before it closes it!?
> >
> > btw the prog shall creat 6 different 2-digit long numbers.
> >
> > thx a lot guys
> >
> > _________________________________________________________________
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