isspace

int isspace( int ch );

Checks if the given character is either

• A standard white-space character:
• Space (0x20, ' '),
• Form feed (0x0c, '\f'),
• Line feed (0x0a, '\n'),
• Carriage return (0x0d, '\r'),
• Horizontal tab (0x09, '\t'),
• Vertical tab (0x0b, '\v'),
• Or a locale-specific white-space character.

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

Parameters

Return value

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

Example

#include <ctype.h>
#include <limits.h>
#include <stdio.h>
 
int main(void)
{
    for (int ndx = 0; ndx <= UCHAR_MAX; ndx++)
        if (isspace(ndx))
            printf("0x%02x ", ndx);
}

0x09 0x0a 0x0b 0x0c 0x0d 0x20

References

• C23 standard (ISO/IEC 9899:2023):
• 7.4.1.10 The isspace function (p: TBD)
• C17 standard (ISO/IEC 9899:2018):
• 7.4.1.10 The isspace function (p: 147)
• C11 standard (ISO/IEC 9899:2011):
• 7.4.1.10 The isspace function (p: 202-203)
• C99 standard (ISO/IEC 9899:1999):
• 7.4.1.10 The isspace function (p: 183-184)
• C89/C90 standard (ISO/IEC 9899:1990):
• 4.3.1.9 The isspace function

See also