std::type_info::operator==, std::type_info::operator!=
bool operator==( const type_info& rhs ) const; |
(until C++11) | |
bool operator==( const type_info& rhs ) const noexcept; |
(since C++11) (until C++23) |
|
constexpr bool operator==( const type_info& rhs ) const noexcept; |
(since C++23) | |
bool operator!=( const type_info& rhs ) const; |
(until C++11) | |
bool operator!=( const type_info& rhs ) const noexcept; |
(since C++11) (until C++20) |
Checks if the objects refer to the same types.
| The |
(since C++20) |
Parameters
| rhs | - | another type information object to compare to |
Return value
true if the comparison operation holds true, false otherwise.
Notes
Feature testing macro: __cpp_lib_constexpr_typeinfo.
Example
#include <iostream>
#include <typeinfo>
#include <string>
#include <utility>
class person
{
public:
person(std::string n) : name_(std::move(n)) {}
virtual const std::string& name() const{ return name_; }
private:
std::string name_;
};
class employee : public person
{
public:
employee(std::string n, std::string p)
: person(std::move(n)), profession_(std::move(p)) {}
const std::string& profession() const { return profession_; }
private:
std::string profession_;
};
void print_info(const person& p)
{
if(typeid(person) == typeid(p))
{
std::cout << p.name() << " is not an employee\n";
}
else if(typeid(employee) == typeid(p))
{
std::cout << p.name() << " is an employee ";
auto& emp = dynamic_cast<const employee&>(p);
std::cout << "who works in " << emp.profession() << '\n';
}
}
int main()
{
print_info(employee{"Paul","Economics"});
print_info(person{"Kate"});
# if defined(__cpp_lib_constexpr_typeinfo) // C++23
if constexpr (typeid(employee) != typeid(person))
{
std::cout << "class `employee` != class `person`\n";
}
# endif
}
Possible output:
Paul is an employee who works in Economics Kate is not an employee class `employee` != class `person`
See also
checks whether the referred type precedes referred type of another type_infoobject in the implementation defined order, i.e. orders the referred types (public member function) |
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