质数因子生成c++

到目前为止，我已经完成了以下内容:

//project Eular Problem 4: Prime Factors
#include<iostream>
#include<cmath>
typedef unsigned long long int uint_64;
using namespace std;
void storeFactors(uint_64 factors[], uint_64 num)
{
    for(uint_64 i=0;i*i<num;i++
       factors[i]=1;       //assign 1 to all the values
    for(uint_64 j=2; j*j<num;j++){
       if(num%j!=0)
          factors[j]=0;       //assign 0 to non-factors
    } 
}  
//Sieve of Eratosthenes to generate primes
void gen_primes(uint_64 arr[],uint_64 firstElement, uint_64 lastElement, uint_64 size)
{
    for(uint_64 i=0;i<size;i++)   //assigning 1 to all the values
       arr[i]=1;
    for(uint_64 i=2;i*i<=lastElement;i++){   //loop until the square-root of n
       if(arr[i])
          for(uint_64 j=i;j*i<=lastElement;j++)      //eliminate multiples by assigning them 0
            arr[j*i]=0;
       if(firstElement==1)
          arr[firstElement]=0;
    }
}
void arrayComp(uint_64 factors[],uint_64 primeArray[], uint_64 size)
{
    for(uint_64 i=2; i<=size; i++){
        if(factors[i] && primeArray[i]){
                cout<<i<<endl;
        }
    }
}
void processFactors(uint_64 num)
{
    uint_64 size = sqrt(num);
    uint_64 *factors = new uint_64[size];
    uint_64 *primeArray = new uint_64[size];
    storeFactors(factors, num);
    gen_primes(primeArray, 2, num, size);
    arrayComp(factors, primeArray,size);
    delete [] factors;
    delete [] primeArray;
}
int main()
{
    uint_64 number;
    cout<<"Enter a number: "<<endl;
    cin>>number;
    cout<<"The prime factors of "<<number<<" are: "<<endl;
    processFactors(number);
    return 0;
}

我试着用筛法来计算因子。所有非因子赋值为0。

我遇到的问题是输出不完整，程序运行到分段错误。例如，10的因数是5和2，但它显示100的相同答案。

编辑:另一件我不太自信的事情是数组的大小。这个程序显示3是21的质因数，而不是7，但是如果我把大小增加1，它显示3和5(不正确)