What is a type cast in c plus plus?

Answer 1

A type cast is an override within an expression that causes the compiler to generate conversion code and to treat the item as if it had a different type.

int a = 13;
int b = 4;
float c;

c = a / b; /* result is 3, the integer value of 13 divided by 4 */

c = (float) a / b; /* result is 3.1, the floating value of 13 divided by 4 */

In this case, the (float) keyword was the typecast. Note also that it was not necessary to typecast b, because the compiler recognizes the mixed mode expression.

Answer 2

In order to implement automatic type casting you must provide conversion operator overloads in your object's class definition. Generally it is best not to provide conversion operators unless absolutely necessary; it is always better to implement conversions using explicit member methods instead. However, if you should require a conversion operator, the operator should simply invoke the method.

For instance, if your object can be converted to a std::string object, then you should provide an as_string() method that returns a std::string by value. For automatic conversion, you should provide a conversion overload that invokes the as_string() method:

class foo{

//...

public:

std::string as_string()const;

operator std::string(void)const;

};

std::string foo::as_string()const{

//...

}

foo::operator std::string()const{

return(as_string());

}

Note that conversion operators have no return type since the return type is implied by the operator name.

Answer 3

Automatic type casting is implicit, whereas (non-automatic) type casting is explicit.