Character

Character Class

The value of Character class objects is (on most hardware platforms) an 8-bit integer corresponding to the ISO-8859-1 character set.

Character Constants

Ctalk recognizes the following escape sequences as character constants.

\a      Alert
\b      Bell
\e      Escape
\f      Form Feed
\n      New line
\r      Carraige return
\t      Horizontal tab
\v      Vertical tab
\0      NUL
\"      Literal double quote.
\'      Literal single quote.

The ‘\e’ escape sequence is an extension to the C language standard.

Ctalk itself doesn’t interpret the character constants, though - it simply recognizes that the character or escaped character can be part of a literal string or character. However, if a method encounters a constant, it should interpret the character constant based on the method’s function.

Very often a character constant’s value is enclosed in single quotes if they are part of the token’s name. Again it’s up to the method to interpret the character’s value. The Ctalk library includes the macros TRIM_CHAR() and TRIM_CHAR_BUF() that can remove the quotes from the character sequences if necessary.

Note: Ctalk does not support negative Characters (i.e., ch < 0) universally, even though C char types are “signed” by default. This is due to the uneven support in the Ctalk and C libraries for negative characters. So if you need negative values, it’s generally safer to use Integers.

Additionally, if an expression doesn’t need a separate buffer for function arguments, it can also use the CHAR_CONSTANT_VALUE macro, which returns a string with the first character pointing to the Character constant’s actual value. The argument to the macro is a C char *. Here is an example of how to store the value of a Character object in a C char.

char c;
OBJECT *self_value;

self_value = self value;

sscanf (CHAR_CONSTANT_VALUE(self_value -> __o_value), "%c", &c);

Instance Variables

value

The value of an 8-bit character in the ISO-8859-1 character set.

Instance Methods

! (void)

Return a character value of true if the receiver evaluates to zero, false otherwise.

!= (char character)

Returns true if the receiver is not equal to character.

& (char character)

Returns a bitwise AND of the receiver and the argument.

&& (char character)

Returns TRUE if both operands are TRUE, FALSE otherwise.

* (char c)

Multiply the receiver and the operand. The result is a Character object.

*= (char c)

Multiply the receiver by the operand, and return the receiver.

+ (char c)

Add the receiver and the operand. The result is a Character object.

++ (void)

The prefix and postfix increment operators for Character objects.

+= (char c)

Add the operand to the receiver and the operand and return the receiver.

- (char c)

Subtract the receiver and the operand. The result is a Character object.

-- (void)

The prefix and postfix decrement operators for Character objects.

-= (char c)

Subtract the operand from the receiver and return the receiver.

/ (char c)

Divide the receiver and the operand. The result is a Character object.

/= (char c)

Divide the receiver by the operand and return the receiver.

< (char character)

Returns TRUE if the receiver is less than the operand, FALSE otherwise.

<< (int i)

Shift the receiver left by the number of bits in the operand, which must be an Integer.

<= (char character)

Returns TRUE if the receiver is less than or equal to the operand, FALSE otherwise.

= (char character)

Set the value of the receiver object to character.

> (char character)

Returns TRUE if the receiver is greater than the operand, FALSE otherwise.

>> (int i)

Shift the receiver right by the number of bits in the operand, which must be an Integer.

>= (char character)

Returns TRUE if the receiver is greater than or equal to the operand, FALSE otherwise.

== (char character)

Returns true if the receiver is equal to character.

^ (char character)

Returns a bitwise XOR of the receiver and the argument.

Returns a Character object that is the bitwise complement of the receiver. This method simply calls bitComp, below.

bitComp (void)

Perform a bitwise complement of the receiver.

invert (void)

Returns TRUE if the receiver evaluates to FALSE, FALSE if the receiver evaluates to TRUE.

isASCII (void)

Returns TRUE if the receiver is a 7-bit ASCII character ‘0-127’, FALSE otherwise.

isAlNum (void)

Returns TRUE if the receiver is an alphanumeric character ‘0-9’, ‘A-Z’, ‘a-z’, FALSE otherwise.

isAlpha (void)

Returns TRUE if the receiver is an alphabetic character ‘A-Z’, ‘a-z’, FALSE otherwise.

isBlank (void)

Returns TRUE if the receiver is a space ‘ ’ or horizontal tab ‘\t’ character, FALSE otherwise.

isCntrl (void)

Returns TRUE if the receiver is a control character, FALSE otherwise.

isDigit (void)

Returns TRUE if the receiver is a character ‘0-9’, FALSE otherwise.

isGraph(void)

Returns TRUE if the receiver is any character except a space, FALSE otherwise.

isLower (void)

Returns TRUE if the receiver is a lower case character, FALSE otherwise.

isPrint (void)

Returns TRUE if the receiver is a printable character, FALSE otherwise.

isPunct (void)

Returns TRUE if the receiver is a printable non-alphanumeric character, FALSE otherwise.

isSpace (void)

Returns TRUE if the receiver is a space, horizontal tab (\t), newline (\n), vertical tab (\v), form feed (\f), or carriage return (\r) character, FALSE otherwise.

isUpper (void)

Returns TRUE if the receiver is an upper case letter, FALSE otherwise.

isXDigit (void)

Returns TRUE if the receiver is a character ‘0-9’, ‘a-f’, or ‘A-F’, FALSE otherwise.

toLower (void)

If the receiver is an upper case letter, returns the lower case version.

toUpper (void)

If the receiver is a lower case letter, returns the upper case version.

| (char character)

Returns a bitwise OR of the receiver and the argument.

|| (char character)

Returns TRUE if either operand is TRUE, FALSE otherwise.