HP OpenVMS Systems

Indicates if a specified file descriptor is associated with a pipe.

Format

#include <unixio.h>

int isapipe (int file_desc);

Argument

file_desc

A file descriptor.

Description

For more information about pipes, see Chapter 5.

Return Values

1	Indicates an association with a pipe.
0	Indicates no association with a pipe.
- 1	Indicates an error (for example, if the file descriptor is not associated with an open file).

Indicates if a character is an ASCII character.

Format

#include <ctype.h>

int isascii (int character);

Argument

character

An object of type char .

Return Values

nonzero	If ASCII.
0	If not ASCII.

Indicates if a specified file descriptor is associated with a terminal.

Format

#include <unistd.h>

int isatty (int file_desc);

Argument

file_desc

A file descriptor.

Return Values

1	If the file descriptor is associated with a terminal.
0	If the file descriptor is not associated with a terminal.
- 1	Indicates an error (for example, if the file descriptor is not associated with an open file).

Indicates if a character is classed as a control character in the program's current locale.

Format

#include <ctype.h>

int iscntrl (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a control character.
0	If not a control character.

Indicates if a character is classed as a digit in the program's current locale.

Format

#include <ctype.h>

int isdigit (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a decimal digit.
0	If not a decimal digit.

Indicates if a character is classed as a graphic character in the program's current locale.

Format

#include <ctype.h>

int isgraph (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a graphic character.
0	If not a graphic character.

Indicates if a character is classed as a lowercase character in the program's current locale.

Format

#include <ctype.h>

int islower (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a lowercase alphabetic character.
0	If not a lowercase alphabetic character.

Tests for a NaN. Returns 1 if the argument is NaN; 0 if not.

Format

#include <math.h>

int isnan (double x);

int isnanf (float x);

int isnanl (long double x);

Argument

x

A real value.

Description

The isnan functions return the integer value 1 (TRUE) if x is NaN (the IEEE floating point reserved not-a-number value); otherwise, they return the value 0 (FALSE).

Indicates if a character is classed as a printing character in the program's current locale.

Format

#include <ctype.h>

int isprint (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a printing character.
0	If not a printing character.

Indicates if a character is classed as a punctuation character in the program's current locale.

Format

#include <ctype.h>

int ispunct (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a punctuation character.
0	If not a punctuation character.

Indicates if a character is classed as white space in the program's current locale; that is, if it is an ASCII space, tab (horizontal or vertical), carriage-return, form-feed, or new-line character.

Format

#include <ctype.h>

int isspace (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a white-space character.
0	If not a white-space character.

Indicates if a character is classed as an uppercase character in the program's current locale.

Format

#include <ctype.h>

int isupper (int character);

Argument

character

An object of type int . The value of character must be representable as an unsigned char or must equal the value of the macro EOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If an uppercase alphabetic character.
0	If not an uppercase alphabetic character.

Indicates if a wide character is classed either as alphabetic or as a digit in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswalnum (wint_t wc);

Argument

wc

An object of type wint_t . The value of character must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If alphanumeric.
0	If not alphanumeric.

Indicates if a wide character is classed as an alphabetic character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswalpha (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If alphabetic.
0	If not alphabetic.

Indicates if a wide character is classed as a control character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswcntrl (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a control character.
0	If not a control character.

Indicates if a wide character has a specified property.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswctype (wint_t wc, wctype_t wc_prop);

Arguments

wc

An object of type wint_t . The value of wc must be representable as a valid wide-character code in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

wc_prop

A valid property name in the current locale. This is set up by calling the wctype function.

Description

The iswctype function tests whether wc has the character-class property wc_prop. Set wc_prop by calling the wctype function.

See also wctype .

Return Values

nonzero	If the character has the property wc_prop.
0	If the character does not have the property wc_prop.

Example

#include <locale.h> #include <wchar.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <ctype.h> /* This test will set up the "upper" character class using */ /* wctype() and then verify whether the characters 'a' and 'A' */ /* are members of this class */ #include <stdlib.h> main() { wchar_t w_char1, w_char2; wctype_t ret_val; char *char1 = "a"; char *char2 = "A"; ret_val = wctype("upper"); /* Convert char1 to wide-character format - w_char1 */ if (mbtowc(&w_char1, char1, 1) == -1) { perror("mbtowc"); exit(EXIT_FAILURE); } if (iswctype((wint_t) w_char1, ret_val)) printf("[%C] is a member of the character class upper\n", w_char1); else printf("[%C] is not a member of the character class upper\n", w_char1); /* Convert char2 to wide-character format - w_char2 */ if (mbtowc(&w_char2, char2, 1) == -1) { perror("mbtowc"); exit(EXIT_FAILURE); } if (iswctype((wint_t) w_char2, ret_val)) printf("[%C] is a member of the character class upper\n", w_char2); else printf("[%C] is not a member of the character class upper\n", w_char2); }

Running the example program produces the following result:

[a] is not a member of the character class upper [A] is a member of the character class upper

Indicates if a wide character is classed as a digit in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswdigit (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a decimal digit.
0	If not a decimal digit.

Indicates if a wide character is classed as a graphic character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswgraph (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a graphic character.
0	If not a graphic character.

Indicates if a wide character is classed as a lowercase character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswlower (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a lowercase character.
0	If not a lowercase character.

Indicates if a wide character is classed as a printing character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswprint (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a printing character.
0	If not a printing character.

Indicates if a wide character is classed as a punctuation character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswpunct (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a punctuation character.
0	If not a punctuation character.

Indicates if a wide character is classed as a space character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswspace (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If a white-space character.
0	If not a white-space character.

Indicates if a wide character is classed as an uppercase character in the program's current locale.

Format

#include <wctype.h> (ISO C)

#include <wchar.h> (XPG4)

int iswupper (wint_t wc);

Argument

wc

An object of type wint_t . The value of wc must be representable as a wchar_t in the current locale, or must equal the value of the macro WEOF. If it has any other value, the behavior is undefined.

Return Values

nonzero	If an uppercase character.
0	If not an uppercase character.