Static cast
Encyclopedia
In C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
type conversion
Type conversion
In computer science, type conversion, typecasting, and coercion are different ways of, implicitly or explicitly, changing an entity of one data type into another. This is done to take advantage of certain features of type hierarchies or type representations...
, the static_cast operator
Operators in C and C++
This is a list of operators in the C and C++ programming languages. All the operators listed exist in C++; the fourth column "Included in C", dictates whether an operator is also present in C...
changes expressions of one static type to objects and values of another static type.
Syntax
static_cast
The type parameter must be a data type for which there is a known method for converting object to, whether this be a builtin or through a casting function. It can be a reference or an enumerator.
All types of conversions that are well-defined and allowed by the compiler are done using static_cast. These include typical castless conversions, narrowing conversions, forcing a conversion from a void*, implicit type conversions and static navigation of class hierarchies.
The static_cast operator can be used for operations such as
- Converting a pointer of a base class to a pointer of a derived class,
- Convert numeric data types such as enumsEnumerated typeIn computer programming, an enumerated type is a data type consisting of a set of named values called elements, members or enumerators of the type. The enumerator names are usually identifiers that behave as constants in the language...
to intsInteger (computer science)In computer science, an integer is a datum of integral data type, a data type which represents some finite subset of the mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values....
or ints to floatsFloating pointIn computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
.
However, static_cast conversions are not necessarily safe as no run-time type check is done which can cause casting between incompatible data types, for example pointers. However, this is checked at compile time to prevent casting obviously incompatibles. Also, sometimes static_cast between pointer of base to pointer of derived will produce an erroneous result, because of the object layout model.