Program keeps on crashing...

[AsianSensation]

We were suppose to make a simple program that tells if a number is prime or not, but my program keeps on crashing, the windows xp error message keeps on popping up, and I don't know what's wrong, can someone help me? btw, I'm using Dev c++

code:

#include <iostream.h> #include <math.h> int main () {     int num;     cout << "Please input a number between 1 - 1000, inclusive\n";     cin >> num;         for (int i = 0; i < sqrt (num); i++)     {         if (num % i == 0)             {                 cout << "This number is not prime\n";             }     }           cin.ignore (1, '\n');     return 0; }

[Mazer]

i haven't tried to run your program, but my guess is that it's trying to do a modulus by 0.

[AsianSensation]

OMG!!!!

Stupid Stupid Stupid.....

All those math practices.....

and I make this mistake.....

[Tony]

you got this code all wrong... the division check should start with 2 ( cuz remember - prime is divisible by 1 and itself). Though that would be wrong too since 2 itself is a prime number. And would screw up your loop if sqrt(num) <2

I remember posting a really efficient algorithm for finding prime numbers... You should search for that on forum, that might come in handy

[AsianSensation]

yeah, I did that when I fixed the code

lol, I was brain dead or something, recently, I keep finding myself in situations that I shouldn't be in...

for example, in my data management class, I was doing permutations, and I thought P(n, r) was n! / r!... I'm making sooo many simple :newbie: mistakes....