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:
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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;
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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&()
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returns a reference and is an l-value. However, a conversion declared as
operator int()
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returns an object and is not an l-value.