Standard Conversions

The C++ language defines conversions between its fundamental types. It also defines conversions for pointer, reference, and pointer-to-member derived types. These conversions are called "standard conversions." (For more information about types, standard types, and derived types, see Types.)

This section discusses the following standard conversions:

• Integral promotions

• Integral conversions

• Floating conversions

• Floating and integral conversions

• Arithmetic conversions

• Pointer conversions

• Reference conversions

• Pointer-to-member conversions

  Notes

  User-defined types can specify their own conversions. Conversion of user-defined types is covered in Constructors and Conversions.

The following code causes conversions (in this example, integral promotions):

long  lnum1, lnum2;
int   inum;

// inum promoted to type long prior to assignment.
lnum1 = inum;

// inum promoted to type long prior to multiplication.
lnum2 = inum * lnum2;

Notes

The result of a conversion is an l-value only if it produces a reference type. For example, a user-defined conversion declared as

operator int&()

Notes

returns a reference and is an l-value. However, a conversion declared as

operator int()

Notes

returns an object and is not an l-value.

See Also

Concepts

C++ Language Reference