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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 unsigned char and is not equal to EOF .

[edit] Parameters

[edit] Return value

Non-zero value if the character is a whitespace character, zero otherwise.

[edit] Notes

Like all other functions from <cctype>, the behavior of std::isspace 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_isspace(char ch)
{
 return std::isspace(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_spaces(const std::string & s)
{
 return std::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
 [](unsigned char c){ return std::isspace(c); } // correct
 );
}

[edit] Example

#include <cctype>
#include <climits>
#include <iomanip>
#include <iostream>
 
int main(void)
{
 std::cout << std::hex << std::setfill ('0') << std::uppercase ;
 for (int ch{}; ch <= UCHAR_MAX ; ++ch)
 if (std::isspace(ch))
 std::cout << std::setw (2) << ch << ' ';
 std::cout << '\n';
}

09 0A 0B 0C 0D 20

[edit] See also

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