NAME¶

std::type_info::operator==,std::type_info::operator!= - std::type_info::operator==,std::type_info::operator!=

Synopsis¶

bool operator==( const type_info& rhs ) const; (until C++11)
bool operator==( const type_info& rhs ) const (since C++11)
noexcept; (until C++23)
constexpr bool operator==( const type_info& rhs (1) (since C++23)
) const noexcept;
bool operator!=( const type_info& rhs ) const; (until C++11)
bool operator!=( const type_info& rhs ) const (2) (since C++11)
noexcept; (until C++20)

Checks if the objects refer to the same types.

The != operator is synthesized from operator==. (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-test macro Value Std Feature
__cpp_lib_constexpr_typeinfo 202106L (C++23) Constexpr for
std::type_info::operator==

Example¶

// Run this code

#include <iostream>
#include <string>
#include <typeinfo>
#include <utility>

class person
{
public:
explicit 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 __cpp_lib_constexpr_typeinfo
if constexpr (typeid(employee) != typeid(person)) // C++23
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_info
before object in the implementation defined order, i.e. orders the referred types
(public member function)