# std::ctype<char>::is

From cppreference.com
< cpp‎ | locale‎ | ctype char

Defined in header `<locale>` |  |
bool is(mask m, char c) const; | (1) |
const char* is(const char* low, const char* high, mask* vec) const; | (2) |

1) Checks if the character `c` is classified by the mask `m` according to the classification table returned by the member function table(). Effectively calculates table()[(unsigned char)c] & m
2) For every character in the character array `[low, high)`, reads its full classification mask from the classification table returned by the member function table() (that is, evaluates table()[ (unsigned char)*p] and stores it in the corresponding element of the array pointed to by `vec`

If (unsigned char)c >= std::ctype<char>::table_size, then an implementation-defined value is substituted instead of table()[(unsigned char)c], possibly different for different values of c.

### Parameters

c | - | character to classify
m | - | mask to use for classifying a single character
low | - | pointer to the first character in an array of characters to classify
high | - | one past the end pointer for the array of characters to classify
vec | - | pointer to the first element of the array of masks to fill

### Return value

1) true if `c` is classified by `m` in table()
2) `high`

### Notes

Unlike the primary template std::ctype, this specialization does not perform a virtual function call when classifying characters. To customize the behavior, a derived class may provide a non-default classification table to the base class constructor.

### Example

| This section is incomplete Reason: no example

### See also

do_is [virtual] | classifies a character or a character sequence (virtual protected member function of `std::ctype<CharT>`)

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/locale/ctype_char/is&oldid=105261"