PLVchr: Operations on Single Characters

The PLVchr (PL/Vision CHaRacter) package provides information about single characters in a string. See the companion disk for details.

PLVchr constants

• blank_char CONSTANT CHAR(1) := ' ';
• space_char CONSTANT CHAR(1) := ' ';
• quote1_char CONSTANT CHAR(1) := '''';
• quote2_char CONSTANT CHAR(2) := '''''';
• tab_char CONSTANT CHAR(1) := CHR(9);
• newline_char CONSTANT CHAR(1) := CHR(10);
• Named constants to use in place of hard-coded literals. Sure, there is more typing involved. But at least you don't have to mess with single quotes, and the code is a lot more readable.
• c_nonprinting CONSTANT CHAR(1) := 'n';
• c_digit CONSTANT CHAR(1) := '9';
• c_letter CONSTANT CHAR(1) := 'a';
• c_other CONSTANT CHAR(1) := '*';
• c_all CONSTANT CHAR(1) := '%';
• Action codes for use in PLVchr programs that allow you to specify the category of character that you want to work with.

Character type functions

• FUNCTION is_quote (char_in IN VARCHAR2) RETURN BOOLEAN;
• FUNCTION is_blank (char_in IN VARCHAR2) RETURN BOOLEAN;
• Functions to encapsulate hard-coded checks for contents of the strings.
• FUNCTION is_nonprinting (code_in IN INTEGER) RETURN BOOLEAN;
• FUNCTION is_nonprinting (letter_in IN VARCHAR2) RETURN BOOLEAN;
• Returns TRUE if the character (or, overloaded as this function is, the ASCII code) is a non-printing character.
• FUNCTION is_digit (code_in IN INTEGER) RETURN BOOLEAN;
• FUNCTION is_digit (letter_in IN VARCHAR2) RETURN BOOLEAN;
• Returns TRUE if the character (or, overloaded as this function is, the ASCII code) is a digit (0 through 9).
• FUNCTION is_letter (letter_in IN VARCHAR2) RETURN BOOLEAN;
• FUNCTION is_letter (code_in IN INTEGER) RETURN BOOLEAN;
• Returns TRUE if the character (or, overloaded as this function is, the ASCII code) is a letter (a-z or A-Z).
• FUNCTION is_other (code_in IN INTEGER) RETURN BOOLEAN;
• FUNCTION is_other (letter_in IN VARCHAR2) RETURN BOOLEAN;
• Returns TRUE if the character (or ASCII code) is not a letter, digit, or nonprinting character.

Other functions and procedures

• FUNCTION char_name (letter_in IN VARCHAR2) RETURN VARCHAR2;
• FUNCTION char_name (code_in IN INTEGER) RETURN VARCHAR2;
• Returns the name of the provided character. This name is actually a standard abbreviation for the character, such as NL for new line. The name of a printable character is simply the character itself. You can pass either a character or an integer code to see the name.
• FUNCTION quoted1 (string_in IN VARCHAR2) RETURN VARCHAR2;
• FUNCTION quoted2 (string_in IN VARCHAR2) RETURN VARCHAR2;
• Each function returns a string wrapped inside the number of single quote marks needed to allow the string to be evaluated to a string surrounded by one and two single quote marks, respectively.
• FUNCTION stripped (string_in IN VARCHAR2, char_in IN VARCHAR2)
• RETURN VARCHAR2;
• Strips a string of all instances of the specified characters. This function is a frontend to TRANSLATE.
• PROCEDURE show_string
• (string_in IN VARCHAR2, flags_in IN VARCHAR2 := c_all);
• Displays the ASCII code and its associated character for each character in the specified string. You can request to view only certain kinds of characters.
• PROCEDURE show_table
• (start_code_in IN INTEGER := 1,
• end_code_in IN INTEGER := NULL);
• Displays the ASCII code and its associated character for all codes within the specified start-end range.