The static_cast operator (C++ only)

The static_cast operator converts a given expression to a specified type.

static_cast operator syntax


1  static_cast < Type > ( expression )

C++11With the right angle bracket feature, you may specify a template_id as Type in the static_cast operator with the >> token in place of two consecutive > tokens. For details, see Class templates (C++ only).C++11

The result of static_cast<Type>(expression) belongs to one of the following value categories:
  • If Type is an lvalue reference type C++11or an rvalue reference to a function typeC++11, static_cast<Type>(expression) is an lvalue.
  • C++11If Type is an rvalue reference to an object type, static_cast<Type>(expression) is an xvalue.C++11
  • In all other cases, static_cast<Type>(expression) is a C++11(prvalue)C++11 rvalue.

An example of the static_cast operator:

#include <iostream>
using namespace std;

int main() {
  int j = 41;
  int v = 4;
  float m = j/v;
  float d = static_cast<float>(j)/v;
  cout << "m = " << m << endl;
  cout << "d = " << d << endl;
}
The output of this example is:
m = 10
d = 10.25

In this example, m = j/v; produces an answer of type int because both j and v are integers. Conversely, d = static_cast<float>(j)/v; produces an answer of type float. The static_cast operator converts variable j to type float. This allows the compiler to generate a division with an answer of type float. All static_cast operators resolve at compile time and do not remove any const or volatile modifiers.

Applying the static_cast operator to a null pointer converts it to a null pointer value of the target type.

The compiler supports the following types of cast operations:
  • An lvalue of type A to type B&, and the cast result is an lvalue of type B
  • C++11An lvalue or xvalue of type A to type B&&, and the cast result is an xvalue of type BC++11
  • A C++11(prvalue)C++11 rvalue of pointer to A to pointer to B
  • C++11An lvalue of type A to type B&& if an xvalue of type A can be bound directly to a reference of type B&&C++11
  • An expression e to type T if the direct initialization T t(e) is valid.
To support the first three cast operations, the following conditions must be satisfied:
  • A is a base class of B.
  • There exists a standard conversion from a pointer to type B to a pointer to type A.
  • Type B is the same as or more cv-qualified than type A.
  • A is not a virtual base class or a base class of a virtual base class of B.
You can cast a C++11(prvalue)C++11 rvalue of a pointer to member of A whose type is cv1 T to a C++11(prvalue)C++11 rvalue of a pointer to member of B whose type is cv2 T if the following conditions are satisfied:
  • B is a base class of A.
  • There exists a standard conversion from a pointer to member of B whose type is T to a pointer to member of A whose type is T.
  • cv2 is the same or more cv-qualification than cv1.

You can explicitly convert a pointer to cv1 void to a pointer to cv2 void if cv2 is the same or more cv-qualification than cv1.