RetroSearch Browse

Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://en.cppreference.com/w/cpp/algorithm/../ranges/../types/type_info/operator_cmp.html below:

std::type_info::operator==, std::type_info::operator!= - cppreference.com

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

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

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

(2) (noexcept since C++11)
(until C++20)

Checks if the objects refer to the same types.

The != operator is synthesized from operator==.

(since C++20) [edit] Parameters rhs - another type information object to compare to [edit] Return value

true if the comparison operation holds true, false otherwise.

[edit] Notes [edit] 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
}

Possible output:

Paul is an employee who works in Economics
Kate is not an employee
class `employee` != class `person`

[edit] See also checks whether the referred type precedes referred type of another type_info
object in the implementation defined order, i.e. orders the referred types
(public member function) [edit]

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4