Type conversions
An expression of a given type is implicitly converted when
it is used in the following situations:
- As an operand of an arithmetic or logical operation.
- As a condition in an if statement or an iteration statement (such as a for loop). The expression will be converted to a Boolean (or an integer in C89).
- In a switch statement. The expression is converted to an integral type.
- As the right operand of an assignment or as an initializer.
- As an initialization. This includes the following types:
- A function is provided an argument value that has a different type than the parameter.
- The value specified in the return statement of a function has a different type from the defined return type for the function.
The implicit conversion result
is an rvalue.
The
implicit conversion result belongs to one of the following value categories
depending on different converted expressions types:- An lvalue if the type is an lvalue reference type
or an rvalue reference to a function type
- An xvalue if the type is an rvalue reference to
an object type
- A (prvalue) rvalue in other cases
You can perform explicit type conversions using a cast expression, as described in Cast expressions.
Vector type casts (IBM extension)
Vector types can be cast to other vector types. The cast does not perform a conversion: it preserves the 128-bit pattern, but not necessarily the value. A cast between a vector type and a scalar type is not allowed.
Vector pointers and pointers to non-vector types can be cast back and forth to each other. When a pointer to a non-vector type is cast to a vector pointer, the address should be 16-byte aligned. The referenced object of the pointer to a non-vector type can be aligned on a 16-byte boundary by using either the __align type qualifier or __attribute__((aligned(16))).
