The std::is_scalar template of C++ STL is used to check whether the given type is a scalar type or not. It returns a boolean value showing the same.
Syntax:
template < class T > struct is_scalar;
Parameter: This template accepts a single parameter T (Trait class) to check whether T is a scalar type or not.
Return Value: This template returns a boolean value as shown below:
- True: if the type is a scalar type.
- False: if the type is a non-scalar type.
Below programs illustrate the std::is_scalar template in C++ STL:
Program 1:
// C++ program to illustrate // std::is_scalar template #include <iostream> #include <type_traits> using namespace std;
class GFG1 {
}; enum class GFG2 {
var1,
var2,
var3,
var4
}; // main program int main()
{ cout << boolalpha;
cout << "is_scalar:"
<< endl;
cout << "GFG1: "
<< is_scalar<GFG1>::value
<< endl;
cout << "GFG2: "
<< is_scalar<GFG2>::value
<< endl;
cout << "int[10]: "
<< is_scalar< int [10]>::value
<< endl;
cout << "int &: "
<< is_scalar< int &>::value
<< endl;
cout << "char: "
<< is_scalar< char >::value
<< endl;
return 0;
} |
Output:
is_scalar: GFG1: false GFG2: true int[10]: false int &: false char: true
Program 2:
// C++ program to illustrate // std::is_scalar template #include <iostream> #include <type_traits> using namespace std;
// main program int main()
{ class gfg {
};
cout << boolalpha;
cout << "is_scalar:"
<< endl;
cout << "int(gfg::*): "
<< is_scalar< int (gfg::*)>::value
<< endl;
cout << "int *: "
<< is_scalar< int *>::value
<< endl;
cout << "bool: "
<< is_scalar< bool >::value
<< endl;
cout << "int(int): "
<< is_scalar< int ( int )>::value
<< endl;
return 0;
} |
Output:
is_scalar: int(gfg::*): true int *: true bool: true int(int): false
Program 3:
// C++ program to illustrate // std::is_scalar template #include <iostream> #include <type_traits> using namespace std;
// main program union GFG {
int var1;
float var2;
}; int main()
{ cout << boolalpha;
cout << "is_scalar:"
<< endl;
cout << "GFG:"
<< is_scalar<GFG>::value
<< endl;
cout << "float: "
<< is_scalar< float >::value
<< endl;
cout << "double: "
<< is_scalar< double >::value
<< endl;
cout << "char: "
<< is_scalar< char >::value
<< endl;
cout << "nullptr_t: "
<< is_scalar<std::nullptr_t>::value
<< endl;
return 0;
} |
Output:
is_scalar: GFG:false float: true double: true char: true nullptr_t: true