Mixed Type Operations

Conversions

The ability to convert between the two types via static_cast is available as documented in the above class descriptions.

Comparisons and Arithmetics

The following operations are disabled by default. Since we cannot enforce -Wsign-conversion and -Wsign-compare through the compiler, we instead static_assert that the operation is unavailable. This removes a common source of error (search "Sign Conversion" on Stack Overflow).

To enable these operations, define the appropriate configuration macros before including any library headers:

BOOST_INT128_ALLOW_SIGN_COMPARE - enables comparison operators between signed and unsigned types
BOOST_INT128_ALLOW_SIGN_CONVERSION - enables arithmetic operators between signed and unsigned types (implies BOOST_INT128_ALLOW_SIGN_COMPARE)

namespace boost {
namespace int128 {

//=====================================
// Comparison Operators
//=====================================

constexpr bool operator==(uint128_t lhs, int128_t rhs);

constexpr bool operator==(int128_t lhs, uint128_t rhs);

constexpr bool operator!=(uint128_t lhs, int128_t rhs);

constexpr bool operator!=(int128_t lhs, uint128_t rhs);

constexpr bool operator<(uint128_t lhs, int128_t rhs);

constexpr bool operator<(int128_t lhs, uint128_t rhs);

constexpr bool operator<=(uint128_t lhs, int128_t rhs);

constexpr bool operator<=(int128_t lhs, uint128_t rhs);

constexpr bool operator>(uint128_t lhs, int128_t rhs);

constexpr bool operator>(int128_t lhs, uint128_t rhs);

constexpr bool operator>=(uint128_t lhs, int128_t rhs);

constexpr bool operator>=(int128_t lhs, uint128_t rhs);

//=====================================
// Arithmetic Operators
//=====================================

constexpr uint128_t operator+(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator+(int128_t lhs, uint128_t rhs);

constexpr uint128_t operator-(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator-(int128_t lhs, uint128_t rhs);

constexpr uint128_t operator*(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator*(int128_t lhs, uint128_t rhs);

constexpr uint128_t operator/(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator/(int128_t lhs, uint128_t rhs);

constexpr uint128_t operator%(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator%(int128_t lhs, uint128_t rhs);

} // namespace int128
} // namespace boost

Comparisons

If you define BOOST_INT128_ALLOW_SIGN_COMPARE, the operators have the following behavior.

Equality

constexpr bool operator==(uint128_t lhs, int128_t rhs);

constexpr bool operator==(int128_t lhs, uint128_t rhs);

If the int128_t argument is less than 0 returns false. Otherwise, returns the same as static_cast<uint128_t>(lhs) == static_cast<uint128_t>(rhs).

Inequality

constexpr bool operator!=(uint128_t lhs, int128_t rhs);

constexpr bool operator!=(int128_t lhs, uint128_t rhs);

If the int128_t argument is less than 0 returns false. Otherwise, returns the same as static_cast<uint128_t>(lhs) != static_cast<uint128_t>(rhs).

Less Than

constexpr bool operator<(uint128_t lhs, int128_t rhs);

constexpr bool operator<(int128_t lhs, uint128_t rhs);

If lhs is type int128_t returns true if lhs < 0 If rhs is type int128_t returns false if rhs < 0 Otherwise, returns the same as static_cast<uint128_t>(lhs) < static_cast<uint128_t>(rhs).

Less Than or Equal To

constexpr bool operator<=(uint128_t lhs, int128_t rhs);

constexpr bool operator<=(int128_t lhs, uint128_t rhs);

If lhs is type int128_t returns true if lhs < 0 If rhs is type int128_t returns false if rhs < 0 Otherwise, returns the same as static_cast<uint128_t>(lhs) <= static_cast<uint128_t>(rhs).

Greater Than

constexpr bool operator>(uint128_t lhs, int128_t rhs);

constexpr bool operator>(int128_t lhs, uint128_t rhs);

If lhs is type int128_t returns false if lhs < 0 If rhs is type int128_t returns true if rhs < 0 Otherwise, returns the same as static_cast<uint128_t>(lhs) > static_cast<uint128_t>(rhs).

Less Than or Equal To

constexpr bool operator>=(uint128_t lhs, int128_t rhs);

constexpr bool operator>=(int128_t lhs, uint128_t rhs);

If lhs is type int128_t returns false if lhs < 0 If rhs is type int128_t returns true if rhs < 0 Otherwise, returns the same as static_cast<uint128_t>(lhs) >= static_cast<uint128_t>(rhs).

Arithmetic

If you define BOOST_INT128_ALLOW_SIGN_CONVERSION, the operators have the following behavior.

Addition

constexpr uint128_t operator+(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator+(int128_t lhs, uint128_t rhs);

Returns the same as static_cast<uint128_t>(lhs) + static_cast<uint128_t>(rhs)

Subtraction

constexpr uint128_t operator-(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator-(int128_t lhs, uint128_t rhs);

Returns the same as static_cast<uint128_t>(lhs) - static_cast<uint128_t>(rhs)

Multiplication

constexpr uint128_t operator*(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator*(int128_t lhs, uint128_t rhs);

Returns the same as static_cast<uint128_t>(lhs) * static_cast<uint128_t>(rhs)

Division

constexpr uint128_t operator/(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator/(int128_t lhs, uint128_t rhs);

Returns the same as static_cast<uint128_t>(lhs) / static_cast<uint128_t>(rhs)

Modulo

constexpr uint128_t operator%(uint128_t lhs, int128_t rhs);

constexpr uint128_t operator%(int128_t lhs, uint128_t rhs);

Returns the same as static_cast<uint128_t>(lhs) % static_cast<uint128_t>(rhs)

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