std::log2p1

 

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Defined in header <bit>
template< class T > constexpr T log2p1(T x) noexcept;		(since C++20)

If x is not zero, calculates the number of bits needed to store the value x, that is, \(1 + \lfloor log_2(x) \rfloor\)1 + floor(log2(x)). If x is zero, returns zero.

This overload participates in overload resolution only if T is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type.

Return value

Zero if x is zero; otherwise, one plus the base-2 logarithm of x, with any fractional part discarded.