Thread: Array Problem

This: i%prb[q] is saying "take the value that is already stored in array prb, at spot q, and get the remainder of i divided by it."

That's different than if you say: i % q


Quzah.

God Hates Flags.

Code:

while (c--)
    if (i % prb[c] == 0)
        break;

if (c >= 0) {
    /* whatever */
}

Originally Posted by oogabooga

God Hates Flags.

Then someone better tell the Westboro Baptist Church that they've made a spelling mistake.

Code:

#include<stdio.h>
#define MAX 1000
int prost(int x); // This is the function that check if number is prime
...
    int prb[MAX];
    scanf("%d",&n);
    getpr(prb,n);
...
void getpr(int s[],int m)
{
    int g=0,z=1;
    while(z<m)
    {
        z++;
        if(prost(z)==1 && z!=2 && z!=3 && z!=7)
              s[g++]=z;
    }
}

You never actually check to make sure n is less than MAX. Not when you enter it, and not when you run through your array getting primes. You also never actually initialize prb, so it's going to have a bunch of random junk in most spots, and only when you hit a prime just-so will it ever have something valid.

Code:

int prost(int x)
{
    int j;
    for(j=2;j<=x/2;j++)
        if(x%j==0)
            return 0;
    return 1;
}

Why don't you return j?

Code:

    for(i=1;i<n;i++)
        for(q=0;q<10;q++)
           if( i%prb[q]!=0 && i%2==0 && i%3==0 && i%7==0) // Here is where i encounter a problem,
                    printf(" %d ",i);                     //i rly dont understand why %prb[q] dont goes from 0 to 10

I honestly have no idea what you are doing here. Why are you looking at only the first ten array slots in prb?


Quzah.

Originally Posted by TheBigH

Then someone better tell the Westboro Baptist Church that they've made a spelling mistake.

All that mindless hatred, due to a simple typo.

Thank you guys!
Quzah, what do you mean by "You also never actually initialize prb"?
I have to say i just started working with arrays, so i realized it like this, there will be max slots, and in about xxx slots will be stored prime numbers except... , depends on n, and i did understand that the other slots xxx+ will have some junk value.So thats way i wanted to check if there is anything in array between 0 to 10.
Well i didnt return j, because that function only checks if the number is prime and if it is, return 1. I agree with you that, it would be easier and faster with returning j, but i wanted it to be simple.

The program still doesn't work, when i enter n , i get error.

Code:

for(i=1;i<n;i++)
    {
        while(c--)
            if(i % prb[c] == 0)
                break;
        if (c >= 0)
            if(i%2==0 && i%3==0 && i%7==0)
                printf(" %d ",i);
    }