ispunct()

Updated: April 19, 2023

Test a character to see if it's any punctuation character

Synopsis:

#include <ctype.h>

int ispunct( int c );

Arguments:

c
The character you want to test. This must be representable as an unsigned char or be EOF; the behavior for other values is undefined. Because this argument is interpreted as an int, to avoid sign extension on character values greater than 0x7F, you must cast the argument to the unsigned data type; otherwise, the function will behave unpredictably.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The ispunct() function tests for any punctuation character such as a comma (,) or a period (.).

Returns:

Nonzero if c is punctuation; otherwise, zero.

Examples:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

char the_chars[] = { 'A', '!', '.', ',', ':', ';' };

#define SIZE sizeof( the_chars ) / sizeof( char )

int main( void )
{
    int i;

    for( i = 0; i < SIZE; i++ ) {
        if( ispunct( (unsigned)the_chars[i] ) ) {
            printf( "Char %c is a punctuation character\n",
                the_chars[i] );
        } else {
            printf( "Char %c is not a punctuation character\n",
                the_chars[i] );
        }
    }
    
    return EXIT_SUCCESS;
}

produces the output:

Char A is not a punctuation character
Char ! is a punctuation character
Char . is a punctuation character
Char , is a punctuation character
Char : is a punctuation character
Char ; is a punctuation character

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes