NM posted:
I am given an int and have to tell whether the bit representation of
that int is a palindrome or not.
Many people have written a template function which determines whether an
array is a palindrome. If you want to be fancy, you can define your own
class called BitHandle which works exactly like a pointer, and then pass
this object to the pre-written (and maybe even very efficient) palindrome
function. Something like:
Warning: Buggy, sloppily written code...
#include <limits>
template<class T>
class BitHandle {
private:
T const val;
unsigned bit_index;
public:
BitHandle(T const val, unsigned const i)
: val(arg), bit_index(i) {}
BitHandle &operator++() { ++bit_index; return *this; }
BitHandle &operator--() { --bit_index; return *this; }
operator bool() const
{
return val & T(1)<<bit_index;
}
};
int main()
{
unsigned val = 72;
TemplatePalindromeFunction(
BitHandle(val,0),
BitHandle(val,std::numeric_limits<unsigned>::digit s) );
}
bool isIntPalindrome(int num)
{
unsigned int temp = num;
int reversed = 0;
while (num != 0) {
reveresed <<= 1;
Here you shift zero to the left by one place. That will have no effect
whatsoever.
reversed |= (temp & 1);
Here you test if "temp" has its low-order bit set, and it does, then you
set reversed's low-order bit.
temp >>= 1;
You shift temp once to the right, effectively dividing it by 2.
--
Frederick Gotham
