std::ctype::scan_is

Parameters

m

Bitmask of member type mask (inherited from ctype_base) specifying the categories to scan for. If the bitmask combines more than one category, the function returns a pointer to the first character that belongs to any of the categories.
It may be any bitwise combination of the following member bitmask values:

member constant	value	description
space	unspecified (unique bits)	white-space character
print	unspecified (unique bits)	printable character
cntrl	unspecified (unique bits)	control character
upper	unspecified (unique bits)	uppercase letter
lower	unspecified (unique bits)	lowercase letter
alpha	unspecified (unique bits)	alphabetic character
digit	unspecified (unique bits)	decimal digit
punct	unspecified (unique bits)	punctuation character
xdigit	unspecified (unique bits)	hexadecimal digit
alnum	alpha|digit	alpha-numeric character
graph	alnum|punct	character with graphic representation

member constant	value	description
space	unspecified (unique bits)	white-space character
print	unspecified (unique bits)	printable character
cntrl	unspecified (unique bits)	control character
upper	unspecified (unique bits)	uppercase letter
lower	unspecified (unique bits)	lowercase letter
alpha	unspecified (unique bits)	alphabetic character
digit	unspecified (unique bits)	decimal digit
punct	unspecified (unique bits)	punctuation character
xdigit	unspecified (unique bits)	hexadecimal digit
blank	unspecified (unique bits)	blank character
alnum	alpha|digit	alpha-numeric character
graph	alnum|punct	character with graphic representation

See <cctype> for details on how ASCII characters are classified with respect to these categories.

low, high

Pointer to the beginning and end of the sequence of characters. The range used is [low,high), which contains all the characters between low and high, including the character pointed by low but not the character pointed by high.
Note that null characters (if any) are also considered, and the function proceeds beyond them, until a match is found or the entire range is completed.
Member type char_type is the facet's character type (defined as an alias of ctype's template parameter, charT).

Return value

Example

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// ctype::scan_is example
#include <iostream>       // std::cout
#include <locale>         // std::locale, std::ctype, std::use_facet
int main ()
{
  std::locale loc;
  const char quote[] = "Characters do not change. Opinions alter, but characters are only developed.";
                       // (quoting Benjamin Disraeli)
  // get a pointer to the first "punctuation" character:
  const char * p = std::use_facet< std::ctype<char> >(loc).scan_is ( std::ctype<char>::punct, quote, quote+76 );
  std::cout << "The second sentence is: " << p << '\n';
  return 0;
}

The second sentence is: . Opinions alter, but characters are only developed.

Data races

Exception safety

See also

ctype::is

Classify characters (public member function)

ctype::scan_not

Return first character not in category (public member function)

ctype::do_scan_is

Return first character in category [virtual] (protected virtual member function)