pTAL Reference Manual (H06.03+)

Statements
HP pTAL Reference Manual—523746-005
12-41
SCAN and RSCAN
RSCAN
indicates a right-to-left search.
variable
is the identifier, with or without an index, of a variable at which to start the scan.
The following restrictions apply:
•
The variable can be a simple variable, array, read-only array, simple pointer,
structure pointer, structure, or structure data item.
•
The variable can be of any data type but UNSIGNED.
•
The variable cannot have extended indirection.
WHILE
specifies that the scan continues until a character other than test-char occurs
or until a 0 occurs. A scan stopped by a character other than test-char resets
$CARRY. A scan stopped by a 0 sets $CARRY.
UNTIL
specifies that the scan continues either until test-char occurs or until a 0
occurs. A scan stopped by test-char resets the hardware carry bit. A scan
stopped by a 0 sets the hardware carry bit.
test-char
is an INT arithmetic expression whose value is a maximum of eight significant bits
(one byte). A larger value might cause execution errors.
next-addr
is a 16-bit variable to contain the 16-bit byte address of the character that stopped
the scan, regardless of the data type of identifier.
Delimit the scan area with zeros; otherwise, a scan operation might continue to pass all
valid data if either:
•
A SCAN UNTIL operation does not find a zero or the test character.
•
A SCAN WHILE operation does not find a zero or a character other than the test
character.
To delimit the scan area, you can specify zeros as follows:
INT .buffer[-1:10] := [0," John James Jones ",0];
Example 12-45 on page 12-42 converts the word address of an INT array to a byte
address. The assignment statement stores the resulting byte address in a STRING
pointer. The SCAN statement then scans the bytes in the array until it finds a comma.