제 나름대로 이렇게 바꿔봤습니다만...
에러가나오네요~~

#include <iostream.h>
int main()
{
    int count,i,j;
    cout << "Enter Line Length: ";
    cin >> count;

  int space = count / 2;

int i=0;
while(i<=space)
{
    int j=0;
    while(j<space-i)
    {
        cout<<"";
        while(j<2*i+1)
        {
            cout<<"*";
            j++;
        }
        j++;}
    i++;
}
int i=1;
while(i<=space)
{
    int j=1;
    while(j<=i)
    {
        cout<<"";
        int j=2*(space-i)+1;
        while(j>=1)
        {
    cout<<"*";
    j--;
}
j++;
}
i++;
}

return 0;
}