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

Checks if the objects refer to the same types.

# Declarations

bool operator==( const type_info& rhs ) const;

(noexcept since C++11) (constexpr since C++23)

bool operator!=( const type_info& rhs ) const;

(noexcept since C++11) (until 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

#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
}

# See also

before