Reverse Read

, ,
1

Hi,

IP := 2797 SPRINGHILL DR ALBANY, OR, 23456

#TEMP := 2797 SPRINGHILL DR ALBANY
OP1 := 2797 SPRINGHILL DR
OP2 := ALBANY

In the samples shown above i want the outputs has shown in in OP1 and OP2.

First step i am using an examine to find ‘,’ and moving that to the #Temp Variable.

From the #Temp variable i want to do an reverse read to find the position of the first space and from that position move that to OP2.

thanks,
TCS
:smiley:

2

There are several ways to do this;

EXAMINE BACKWARD #TEMP would work

or

MOVE #TEMP (PM=I) TO #TEMP followed by an EXAMINE

or

SEPARATE #TEMP

My guess is that the SEPARATE might be the most efficient, but I have not done a comparison as yet; perhaps later today.

One more possibility, do a SEPARATE on IP and retain the delimiters, then look for the first comma

steve

3

Okay, here is a PC timing comparison of two approaches

DEFINE DATA LOCAL
1 IP (A50) INIT <‘2797 SPRINGHILL DR ALBANY, OR, 23456’>
1 #PIECES (A15/1:20)
1 OP1 (A50)
1 OP2 (A50)
1 #INDEX (I2)
1 #COMMA (I2)
1 #BLANK (I2)
1 #OP2LENGTH (I2)
1 #LOOP (I4)
1 #CPU-START (I4)
1 #CPU-ELAPSED (I4)
END-DEFINE
*
MOVE CPU-TIME TO #CPU-START
SETA. SETTIME
FOR #LOOP = 1 TO 10000
SEPARATE IP INTO #PIECES () WITH RETAINED DELIMITERS
EXAMINE #PIECES (*) FOR ‘,’ GIVING INDEX #INDEX
MOVE #PIECES (#INDEX - 1) TO OP2
COMPRESS #PIECES (1:#INDEX - 2) INTO OP1
END-FOR
COMPUTE #CPU-ELAPSED = *CPU-TIME - #CPU-START
WRITE ‘separate ip’ *TIMD (SETA.) #CPU-ELAPSED

MOVE *CPU-TIME TO #CPU-START
SETB. SETTIME
FOR #LOOP = 1 TO 10000
EXAMINE IP FOR ‘,’ GIVING POSITION #COMMA
EXAMINE DIRECTION BACKWARD SUBSTRING (IP,1,#COMMA) FOR ’ ’ GIVING POSITION #BLANK
MOVE SUBSTRING (IP,1,#BLANK) TO OP1
ADD 1 TO #BLANK
COMPUTE #OP2LENGTH = #COMMA - #BLANK
MOVE SUBSTRING (IP,#BLANK,#OP2LENGTH) TO OP2
END-FOR
COMPUTE #CPU-ELAPSED = *CPU-TIME - #CPU-START
WRITE ‘examine ip’ *TIMD (SETB.) #CPU-ELAPSED
END

Page 1 07-11-26 08:16:44

separate ip 7 66
examine ip 2 19

On the mainframe I think the second approach will look even better since the SUBSTRING facility there was recently rewritten and is substantially more efficient than on the PC.

steve

4

Steve Robinson wrote:

But you will get:

NAT0132 Operand not defined or not of alphanumeric/binary format.

during catalog.

Even with the current NAT42x

EXAMINE DIRECTION BACKWARD

is not supported.

5

My bad. Difficult to keep track of which options are on which platform.

Here is a rewrite of the second approach:

MOVE *CPU-TIME TO #CPU-START
SETC. SETTIME
FOR #LOOP = 1 TO 10000
EXAMINE IP FOR ‘,’ GIVING POSITION #COMMA
MOVE SUBSTRING (IP,1,#COMMA) (PM=I) TO #WORK
EXAMINE #WORK FOR ’ ’ GIVING POSITION #BLANK
COMPUTE #BLANK = #BLANK - 2
MOVE SUBSTRING (#WORK,2,#BLANK) (PM=I) TO OP1
MOVE SUBSTRING (IP,#BLANK) TO OP2
END-FOR
COMPUTE #CPU-ELAPSED = *CPU-TIME - #CPU-START
WRITE ‘examine no backward ip’ *TIMD (SETC.) #CPU-ELAPSED

Here are the three times on the PC

PAGE #   1                    DATE:    Nov 26, 2007
PROGRAM: STRIP03              LIBRARY: INSIDE

separate ip 7 67
examine ip 2 19
examine no backward ip 2 20

So on the PC, the third solution is slightly slower than the second.

On the mainframe, I ran the first and third (second, as noted, will not compile)

separate ip 2 11
examine no backward ip 1 6

So the ratio is about two to one in favor of the last solution.

steve