An integer type with a binary representation.
- Xcode 9.0+
- Swift Standard Library
Binary protocol is the basis for all the integer types provided by the standard library. All of the standard library’s integer types, such as
UInt32, conform to
Converting Between Numeric Types
You can create new instances of a type that conforms to the
Binary protocol from a floating-point number or another binary integer of any type. The
Binary protocol provides initializers for four different kinds of conversion.
You use the default
init(_:) initializer to create a new instance when you’re sure that the value passed is representable in the new type. For example, an instance of
Int16 can represent the value
500, so the first conversion in the code sample below succeeds. That same value is too large to represent as an
Int8 instance, so the second conversion fails, triggering a runtime error.
When you create a binary integer from a floating-point value using the default initializer, the value is rounded toward zero before the range is checked. In the following example, the value
127 is rounded to
127, which is representable by the
128 is rounded to
128, which is not representable as an
Int8 instance, triggering a runtime error.
init?(exactly:) initializer to create a new instance after checking whether the passed value is representable. Instead of trapping on out-of-range values, using the failable
init?(exactly:) initializer results in
When converting floating-point values, the
init?(exactly:) initializer checks both that the passed value has no fractional part and that the value is representable in the resulting type.
init(clamping:) initializer to create a new instance of a binary integer type where out-of-range values are clamped to the representable range of the type. For a type
T, the resulting value is in the range
Bit Pattern Conversion
init(truncating initializer to create a new instance with the same bit pattern as the passed value, extending or truncating the value’s representation as necessary. Note that the value may not be preserved, particularly when converting between signed to unsigned integer types or when the destination type has a smaller bit width than the source type. The following example shows how extending and truncating work for nonnegative integers:
Any padding is performed by sign-extending the passed value. When nonnegative integers are extended, the result is padded with zeroes. When negative integers are extended, the result is padded with ones. This example shows several extending conversions of a negative value—note that negative values are sign-extended even when converting to an unsigned type.
Comparing Across Integer Types
You can use relational operators, such as the less-than and equal-to operators (
==), to compare instances of different binary integer types. The following example compares instances of the