is_lvalue_reference Template in C++
The std::is_lvalue_reference template of C++ STL is used to check whether the type is a lvalue reference type or not. It returns a boolean value showing the same.
Syntax:
template <class T > struct is_lvalue_reference;
Template Parameter: This template accepts a single parameter T (Trait class) to check whether T is a lvalue reference type or not.
Return Value: This template returns a boolean value as shown below:
- True: if the type is a lvalue_reference.
- False: if the type is a non-lvalue_reference.
Below programs illustrate the std::is_lvalue_reference template in C++ STL:
Program 1:
// C++ program to illustrate// std::is_lvalue_reference template #include <iostream>#include <type_traits>using namespace std; // main programclass gfg {}; int main(){ cout << std::boolalpha; cout << "is_lvalue_reference: " << '\n'; cout << "gfg: " << is_lvalue_reference<gfg>::value << '\n'; cout << "gfg&: " << is_lvalue_reference<gfg&>::value << '\n'; cout << "gfg&&: " << is_lvalue_reference<gfg&&>::value << '\n'; return 0;} |
Output:
is_lvalue_reference: gfg: false gfg&: true gfg&&: false
Program 2:
// C++ program to illustrate// std::is_lvalue_reference template #include <iostream>#include <type_traits>using namespace std; // main programint main(){ cout << boolalpha; cout << "is_lvalue_reference: " << '\n'; cout << "int: " << is_lvalue_reference<int>::value << '\n'; cout << "int&: " << is_lvalue_reference<int&>::value << '\n'; cout << "int&&: " << is_lvalue_reference<int&&>::value << '\n'; cout << "char: " << is_lvalue_reference<char>::value << '\n'; cout << "char&: " << is_lvalue_reference<char&>::value << '\n'; cout << "char&&: " << is_lvalue_reference<char&&>::value << '\n'; return 0;} |
Output:
is_lvalue_reference: int: false int&: true int&&: false char: false char&: true char&&: false
Program 3:
// C++ program to illustrate// std::is_lvalue_reference template #include <iostream>#include <type_traits>using namespace std; // main programint main(){ cout << boolalpha; cout << "is_lvalue_reference: " << '\n'; cout << "float: " << is_lvalue_reference<float>::value << '\n'; cout << "float&: " << is_lvalue_reference<float&>::value << '\n'; cout << "float&&: " << is_lvalue_reference<float&&>::value << '\n'; cout << "double: " << is_lvalue_reference<double>::value << '\n'; cout << "double&: " << is_lvalue_reference<double&>::value << '\n'; cout << "double&&: " << is_lvalue_reference<double&&>::value << '\n'; return 0;} |
Output:
is_lvalue_reference: float: false float&: true float&&: false double: false double&: true double&&: false
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