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.

In case of conversion, when evaluating expressions, the compiler breaks each expression down into individual subexpressions. Typically, these subexpressions involve a unary or binary operator and some operands. Most binary operators require their operands to be of the same type. If operands of mixed types are used, the compiler will convert one operand to agree with the other. To do this, it uses a hierarchy of data types:

Long double (highest)
Double
Float
Unsigned long int
Long int
Unsigned int
Int (lowest)

Beside standard conversions, the C++ language defines typecast operators for explicit conversions, also named type casting.