std::isprint
Defined in header <cctype>
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int isprint( int ch ); |
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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
#include <iostream> #include <cctype> #include <clocale> 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'; }
Output:
isprint('\xa0', default C locale) returned false isprint('\xa0', ISO-8859-1 locale) returned true
See also
checks if a character is classified as printable by a locale (function template) | |
checks if a wide character is a printing character (function) |
ASCII values | characters |
isprint |
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---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
decimal | hexadecimal | octal | |||||||||||||
0–8 | \x0 –\x8
|
\0 –\10
|
control codes (NUL , etc.)
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
9 | \x9
|
\11
|
tab (\t )
|
≠0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
10–13 | \xA –\xD
|
\12 –\15
|
whitespaces (\n , \v , \f , \r )
|
≠0
|
0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
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 QRSTUVWXYZ
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
≠0
|
0
|
0
|
0
|
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 qrstuvwxyz
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
0
|
≠0
|
0
|
0
|
123–126 | \x7B –\x7E
|
\172 –\176
|
{|}~
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
127 | \x7F
|
\177
|
backspace character (DEL )
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|