prime numbers help

Dexter (8)
I have this code and whenever it runs it just shows 1. It is supposed to spit out all prime numbers until it hits 1000.
Any help would be appreciated.



#include <cstdlib>
#include <iostream>

using namespace std;
int x=1;
int y;

int main()
{
loop:
int Prime [1000] = {x};
int n=1;
signed int m=1;

if (n/Prime[y]!=1) {
n=n+2;
x++;
x++;
goto loop;
}

else if (n/Prime[y]==1) {
cout << n;
n=n+2;
x++;
x++;
goto loop;
}
else if (n/Prime[y]>=1) {
n=n+2;
x++;
x++;
goto loop;
}
else {n=n+2;
goto loop;
}
system("PAUSE");
}
dolorx (30)
First thing to note is that your inside an infinite loop. I don't believe anyone should use goto's, labels, continue, break (except in switch statments) because it hurts readability for you and others.

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#include <cstdlib>
#include <iostream>

using namespace std;
int x=1;
int y;

   int main()
   {
      loop:  //<----
      int Prime [1000] = {x};
      int n=1;
      signed int m=1;

      if (n/Prime[y]!=1)
      {
         n=n+2;
         x++;
         x++;
         goto loop;  //<----
      }
      else if (n/Prime[y]==1)
      {
         cout << n;
         n=n+2;
         x++;
         x++;
         goto loop;  //<----
      }
      else if (n/Prime[y]>=1)
      {
         n=n+2;
         x++;
         x++;
         goto loop;  //<----
      }
      else
      {
         n=n+2;
         goto loop;  //<----
      }

      system("PAUSE");
}



One way you can remove the labels and the infinite loop is like this.

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#include <cstdlib>
#include <iostream>

#define MAX_PRIME_NUMBER 1000

using namespace std;
int x=1;
int y;

   int main()
   {
     //goes through all the numbers
      for( int i = 1; i < MAX_PRIME_NUMBER; i++)
      {
         //from here down to the end of the for loop you should
         //figure out if the number is prime or not before the end of the for loop
         //and print or save them
         int Prime [1000] = {x};
         int n=1;
         signed int m=1;

         if (n/Prime[y]!=1)
         {
            n=n+2;
            x++;
            x++;
         }
         else if (n/Prime[y]==1)
         {
            cout << n << " ";
            n=n+2;
            x++;
            x++;
         }
         else if (n/Prime[y]>=1)
         {
            n=n+2;
            x++;
            x++;
         }
         else
         {
            n=n+2;
         }
      }

      system("PAUSE");
   }
Last edited on
Dexter (8)
ok ty, my problem comes up where i need to add a number to the array. I tried to use a while loop, but i get runtime error. Any suggestions how i could improve this?
Dexter
Dexter (8)
i get it nvm
Dexter (8)
The only number it outputs is "1 Press any key to close..." thanks on the infinite loop help!
Dexter
dolorx (30)

This is how you can assign values to an array.

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#include <cstdlib>
#include <iostream>

#define MAX_ARRAY 10

using namespace std;

int main(int argc, char *argv[])
{
    int primeNumbers[MAX_ARRAY];
    
    //assign values to the array
    for( int i = 0; i < MAX_ARRAY; i++)
    {
         primeNumbers[i] = i;
    }
    
    //print array
    for( int i = 0; i < MAX_ARRAY; i++)
    {
         cout << primeNumbers[i] << endl;
    }    
    
    system("PAUSE");
    return EXIT_SUCCESS;
}


Prints
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dolorx (30)
...
Last edited on
Dexter (8)
i still get a runtime error... never mind thanks for the help. I'll have my friend come and help out.
Dexter (8)
I still learned a lot though thanks
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