Advanced Oracle PL/SQL Programming with Packages

5.6. 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 (view disk content online at http://examples.oreilly.com/advoracle).

5.6.1. 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.

5.6.2. 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 ...