template <class T> struct is_integral;
| fundamental integral types | 
|---|
| bool | 
| char | 
| char16_t | 
| char32_t | 
| wchar_t | 
| signed char | 
| short int | 
| int | 
| long int | 
| long long int | 
| unsigned char | 
| unsigned short int | 
| unsigned int | 
| unsigned long int | 
| unsigned long long int | 
| member type | definition | 
|---|---|
| value_type | bool | 
| type | either true_type or false_type | 
| member constant | definition | 
|---|---|
| value | either true or false | 
|  |  | 
| is_integral: char: true int: true float: false |