NAME¶

std::isprint - std::isprint

Synopsis¶

Defined in header <cctype>
int isprint( int ch );

Checks if ch is a printable character as classified by the currently installed C
locale. In the default, "C" locale, the following characters are printable:

* digits (0123456789)
* uppercase letters (ABCDEFGHIJKLMNOPQRSTUVWXYZ)
* lowercase letters (abcdefghijklmnopqrstuvwxyz)
* punctuation characters (!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~)
* space ( )

The behavior is undefined if the value of ch is not representable as unsigned char
and is not equal to EOF.

Parameters¶

ch - character to classify

Return value¶

Non-zero value if the character can be printed, zero otherwise.

Notes¶

Like all other functions from <cctype>, the behavior of std::isprint is undefined if
the argument's value is neither representable as unsigned char nor equal to EOF. To
use these functions safely with plain chars (or signed chars), the argument should
first be converted to unsigned char:

bool my_isprint(char ch)
{
return std::isprint(static_cast<unsigned char>(ch));
}

Similarly, they should not be directly used with standard algorithms when the
iterator's value type is char or signed char. Instead, convert the value to unsigned
char first:

int count_prints(const std::string& s)
{
return std::count_if(s.begin(), s.end(),
// static_cast<int(*)(int)>(std::isprint) // wrong
// [](int c){ return std::isprint(c); } // wrong
// [](char c){ return std::isprint(c); } // wrong
[](unsigned char c){ return std::isprint(c); } // correct
);
}

Example¶

// Run this code

#include <cctype>
#include <clocale>
#include <iostream>

int main()
{
unsigned char c = '\xa0'; // the non-breaking space in ISO-8859-1

std::cout << "isprint(\'\\xa0\', default C locale) returned "
<< std::boolalpha << (bool)std::isprint(c) << '\n';

std::setlocale(LC_ALL, "en_GB.iso88591");
std::cout << "isprint(\'\\xa0\', ISO-8859-1 locale) returned "
<< std::boolalpha << (bool)std::isprint(c) << '\n';
}

Possible output:¶

isprint('\xa0', default C locale) returned false
isprint('\xa0', ISO-8859-1 locale) returned true

See also¶

isprint(std::locale) checks if a character is classified as printable by a locale
(function template)
iswprint checks if a wide character is a printing character
(function)
C documentation for
isprint

ASCII values characters iscntrl isprint isspace isblank isgraph ispunct isalnum isalpha isupper islower isdigit isxdigit decimal hexadecimal octal iswcntrl iswprint iswspace iswblank iswgraph iswpunct iswalnum iswalpha iswupper iswlower iswdigit iswxdigit 0–8 \x0–\x8 \0–\10 control codes ≠0 0 0 0 0 0 0 0 0 0 0 0
(NUL, etc.) 9 \x9 \11 tab (\t) ≠0 0 ≠0 ≠0 0 0 0 0 0 0 0 0
whitespaces 10–13 \xA–\xD \12–\15 (\n, \v, \f, ≠0 0 ≠0 0 0 0 0 0 0 0 0 0
\r) 14–31 \xE–\x1F \16–\37 control codes ≠0 0 0 0 0 0 0 0 0 0 0 0 32 \x20 \40 space 0 ≠0 ≠0 ≠0 0 0 0 0 0 0 0 0 33–47 \x21–\x2F \41–\57 !"#$%&'()*+,-./ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0 48–57 \x30–\x39 \60–\71 0123456789 0 ≠0 0 0 ≠0 0 ≠0 0 0 0 ≠0 ≠0 58–64 \x3A–\x40 \72–\100 :;<=>?@ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0 65–70 \x41–\x46 \101–\106 ABCDEF 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 ≠0 71–90 \x47–\x5A \107–\132 GHIJKLMNOP 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 0
QRSTUVWXYZ 91–96 \x5B–\x60 \133–\140 [\]^_` 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0 97–102 \x61–\x66 \141–\146 abcdef 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 ≠0 103–122 \x67–\x7A \147–\172 ghijklmnop 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 0
qrstuvwxyz 123–126 \x7B–\x7E \172–\176 {|}~ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0 127 \x7F \177 backspace ≠0 0 0 0 0 0 0 0 0 0 0 0
character (DEL)