std::isprint

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Text processing library

Localization library

Regular expressions library(C++11)

Formatting library(C++20)

Null-terminated sequence utilities

Byte strings

Multibyte strings

Wide strings

Primitive numeric conversions

to_chars (C++17) to_chars_result (C++17) from_chars (C++17) from_chars_result (C++17) chars_format (C++17)

Text encoding identifications

text_encoding (C++26)

 

Null-terminated byte strings

Functions
Character classification
isalnum isalpha islower isupper isdigit isxdigit	isblank (C++11) iscntrl isgraph isspace isprint ispunct
Character manipulation
tolower	toupper
Conversions to numeric formats
atof atoiatolatoll (C++11) strtolstrtoll (C++11)	strtoulstrtoull (C++11) strtofstrtodstrtold (C++11)(C++11) strtoimaxstrtouimax (C++11)(C++11)
String manipulation
strcpy strncpy strxfrm	strcat strncat
String examination
strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
Character array functions
memchr memcmp memset	memcpy memmove
Miscellaneous
strerror

 

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 unsignedchar 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 unsignedchar nor equal to EOF. To use these functions safely with plain chars (or signedchars), the argument should first be converted to unsignedchar:

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

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

int count_prints(conststd::string& s){returnstd::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[](unsignedchar c){return std::isprint(c);}// correct);}

Example

Run this code

#include <cctype>#include <clocale>#include <iostream>   int main(){unsignedchar 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 iswcntrl	isprint iswprint	isspace iswspace	isblank iswblank	isgraph iswgraph	ispunct iswpunct	isalnum iswalnum	isalpha iswalpha	isupper iswupper	islower iswlower	isdigit iswdigit	isxdigit iswxdigit
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