From cppreference.com
intisspace(intch);Checks if the given character is whitespace character as classified by the currently installed C locale. In the default locale, the whitespace characters are the following:
space (0x20, ' ')
form feed (0x0c, '\f')
line feed (0x0a, '\n')
carriage return (0x0d, '\r')
horizontal tab (0x09, '\t')
vertical tab (0x0b, '\v')
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 is a whitespace character, zero otherwise.
Notes
Like all other functions from
, the behavior of std::isspace 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:
boolmy_isspace(charch){returnstd::isspace(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:
intcount_spaces(conststd::string&s){returnstd::count_if(s.begin(),s.end(),// static_cast<int(*)(int)>(std::isspace) // wrong// [](int c){ return std::isspace(c); } // wrong// [](char c){ return std::isspace(c); } // wrong[](unsignedcharc){returnstd::isspace(c);}// correct);}Example
Run this code
#include<cctype>#include<climits>#include<iomanip>#include<iostream>intmain(void){std::cout<<std::hex<<std::setfill('0')<<std::uppercase;for(intch{};ch<=UCHAR_MAX;++ch)if(std::isspace(ch))std::cout<<std::setw(2)<<ch<<' ';std::cout<<'\n';}Output:
09 0A 0B 0C 0D 20 See also
ASCII values characters
decimal hexadecimal octal 0–8 \x0–\x8\0–\10control codes (NUL, etc.) ≠0000000000009 \x9\11tab (\t) ≠00≠0≠00000000010–13 \xA–\xD\12–\15whitespaces (\n, \v, \f, \r) ≠00≠000000000014–31 \xE–\x1F\16–\37control codes ≠00000000000032 \x20\40space 0≠0≠0≠00000000033–47 \x21–\x2F\41–\57!"#$%&'()*+,-./0≠000≠0≠000000048–57 \x30–\x39\60–\7101234567890≠000≠00≠0000≠0≠058–64 \x3A–\x40\72–\100:;<=>?@0≠000≠0≠000000065–70 \x41–\x46\101–\106ABCDEF0≠000≠00≠0≠0≠000≠071–90 \x47–\x5A\107–\132GHIJKLMNOP
QRSTUVWXYZ0≠000≠00≠0≠0≠000091–96 \x5B–\x60\133–\140[\]^_`0≠000≠0≠000000097–102 \x61–\x66\141–\146abcdef0≠000≠00≠0≠00≠00≠0103–122 \x67–\x7A\147–\172ghijklmnop
qrstuvwxyz0≠000≠00≠0≠00≠000123–126 \x7B–\x7E\172–\176{|}~0≠000≠0≠0000000127 \x7F\177backspace character (DEL) ≠000000000000