Stupid WHILE loop question

A=0
While A<B
BEGIN
Set B=B+1
...statements
END
If B had been = to 1 would the loop process through to the END or exit as soon as B was incremented?

The best way to learn this would be trying by yourself.
Hint: Based on what you posted (B = 1) you will need to learn the keyword BREAK.
AMB
Some guidelines for posting questions...
AYÚDANOS A AYUDARTE, guía básica de consejos para formular preguntas

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Question in ABAP syntax, read & insert data from internal table, while loop

Hi, SDN Fellow.
I am from Java background and learnt ABAP, I don't usually write much ABAP code.
I am trying to implement the following logic in a RFC now.
I have one z-custom database table, the structure as the following:
It has two columns, with these sample data.
Says datable table is ZEMPMGRTAB.
EmployeeID,ManagerID
user10,user1
user9,user1
user8,user1
user7,user2
user6,user2
user5,user2
user4,user2
user2,user1
The logic is this:
I have a input parameter, userid. I am using this parameter to have a select statement to query the record into export table,EXPTAB 'LIKE' table ZEMPMGRTAB.
SELECT * FROM ZEMPMGRTAB
into table EXPTAB
   WHERE EMPLOYEEID = USERID.
Say, my parameter value, USERID ='USER4'.
Referring to the sample data above, I can get the record of this in my EXPTAB,
EmployeeID,ManagerID
user4,user2
Now, I want to iterately use the EXPTABLE-ManagerID
as the USERID input in SELECT statement, until it has no return result. Then, insert the new records in
EXPTAB.
In above new loop case, we will get this table content in EXPTAB,
EmployeeID,ManagerID
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user2,user1
I kind of think of the pseudocode logic as below:
(These may not be a valid ABAP code, so I need help to convert/correct them)
DATA:
IWA TYEP ZZEMPMGRTAB,
ITAB
HASHED TABLE OF ZZEMPMGRTAB
WITH UNIQUE KEY EMPLOYEEID.
SELECT * FROM ZEMPMGRTAB
into table ITAB
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*Question 1: I cannot insert a internal table to export table, it is *incompatible type, what is the alternative way fo this?
*Question 2: How can I access thedata of the internal table like this,ITAB-MANAGERID? As if I can, I would do this:
* IWA-EMPLOYEEE = ITAB-EMPLOYEEID. IWA-MANAGERID = IWA-MANAGERID. INSERT IWA INTO TABLE EXPTAB.
* Question 3: Is the 'NE NULL' - 'not equal to NULL' is right syntax?
IF ITAB NE NULL.
INSERT ITAB INTO EXPTAB.
ENDIF
* Question 4: Is my WHILE loop setup right here? And are the syntax right?
WHILE ITAB NE NULL.
SELECT * FROM ZEMPMGRTAB
into table ITAB
   WHERE EMPLOYEEID = ITAB-MANAGERID.
IF ITAB NE NULL.
INSERT ITAB INTO EXPTAB.
ENDIF
REFRESH ITAB.
ENDWHILE.
Assume all the syntax and logic are right, I should get this result:
EmployeeID,ManagerID
user4,user2
user2,user1
If I have a new entry in datable table,ZEMPMGRTAB like this:
user1,user0
My pseudocode logic will get this result:
EmployeeID,ManagerID
user4,user2
user2,user1
user1,user0
I truly appreciate if you can help me to validate the above syntax and pseudocode logic.
Thanks in advance.
KC

Hi,
FUNCTION ZGETSOMEINFO3.
*"*"Local Interface:
*" IMPORTING
*"     VALUE(USERID) TYPE AWTXT
*"     VALUE(FMTYPEID) TYPE AWTXT
*" EXPORTING
*"     VALUE(RETURN) TYPE BAPIRETURN
*" TABLES
*"      APPROVERT STRUCTURE ZTAB_FMAPPROVER
*"      ACTOWNERT STRUCTURE ZTAB_FMACTOWNER
DATA: T_RESULT TYPE STANDARD TABLE OF ZTAB_FMAPPROVER.
**Question 1: For this line, I got an error says "Program ''USERID" *not found. Is the syntax right, as the USERID is a parameter for the function.
perform add_line(USERID).
ENDFUNCTION.
form add_line using i_user type ZTAB_FMAPPROVER.EMPLOYEEID
                    changing T_RESULT TYPE ZTAB_FMAPPROVER.
data: ls_row type ZTAB_FMAPPROVER.
* Get record for i_user
select single * into ls_row from ZTAB_FMAPPROVER
where EmployeeID = i_user.
if sy-subrc NE 0.
* Do nothing, there is not manager for this employee
else.
* Store result
QUESTION 2: I am still got stuck on this line of code. It still *says that "T_RESULT" is not an internal table "OCCURS n" *specification is missing. I thought the line: "T_RESULT TYPE *ZTAB_FMAPPROVER" means declare internal table, T_RESULT as type of ZTAB_FMAPPROVER". Am I understand it wrongly?
append ls_row to t_result.
* Call recursion
perform add_line using ls_row-ManagerID
                          changing t_result.
endif.
endform.
Thanks,
KC

Question for the math lovers! Using while loop and exponents

Hi there Java geniuses! ; ) A little question here that has been perplexing me for the past few days. I'm trying to create a class that contains a single static method as follows:
public static double exp(double a)
It's supposed to work to calculate an "exp" value much like the Math.exp method of the Math class. Essentially, I need to keep calculating approximations of "exp" until a certain condition is met. This condition is specified in a while loop. Following is what I've written so far. But I can't seem to get the thing to work properly. Any suggestions/ advice would be greatly appreciated! Thanks.
A class that computes the "exp" for a user-defined
value.
public class MyMath
public static double exp(double x)
double dbloldGuess;
double dblnewGuess = 1 + x; // First value for newGuess
double dblcounter = 1;
do
dblcounter++; // increments counter
dbloldGuess = dblnewGuess;
dblnewGuess = dbloldGuess + ((x ** dblcounter) / counter);
while (Math.abs((newGuess - oldGuess) / newGuess) > 1e-15);
return x;
}

** wasn't an operator in C when I last checked...
Anyway here's my lousy attempt:public static double exp(double a) {
        double guess = 1;
        int N = 18;
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        return guess;
}When called with 1.0 as argument gives the value equal to the constant Math.E, so is "probably" ok for arguments 0.0 -- 1.0. I wont guarantee anything else because this method is pretty pathological when it comes to loss of precision due to rounding, even if you increase N.

Question about while loop using Timer?

I am trying to use a while loop to read data from oscilloscope through
GPIB card continously(lasting for a fixed time, for example,1 minute). I
want a Timer, when it expires, the while loop will stop. But I do not
know how to implement it.
Any help would be greatly appriciated!
Thanks in advance.
zhljh
Sent via Deja.com http://www.deja.com/
Before you buy.

In article <87q5t2$7kh$[email protected]>, wrote:
>I am trying to use a while loop to read data from oscilloscope through
>GPIB card continously(lasting for a fixed time, for example,1 minute). I
>want a Timer, when it expires, the while loop will stop. But I do not
>know how to implement it.
So, you need it to count down, then I assume? Okay, you need to put a
true/false node within your for loop. Set the true case to i=1 (iteration
of the for loop) so that it will initialize one time (and be true one
time). Then, add whatever time you need for the vi to run to that
indicator (where you send a numeric value on the first iteration). Put a
greater than comparison to the timer and the additoin of the indicator and
your value. Let that be the term
inating thing on your for loop.
Now, this might present a problem with a circular reference. If it does,
you'll need to basically do the same thing, only you'll need to send the
value through a shift register in the for loop.
Harry

Another novice question...I opened a file used "Concatenate String" to write to file creating headers and so forth...a "While Loop" routine is m

onitoring a voltage and storing it to the same file under the associated header...What I'm having problems doing is after the loop is completed I need to write the MIN\MAX values of the voltage that was monitored in the "While Loop" once it completes. I juBefore the loop the "Concatenate String" peforms the following... line1 col.1 in an excel file is (Tester then Line1 col.2 (the testers name appears) next is a end of line. Then Line2 col.1 is (DATE)header then col.2(TIME)header then col.3(throttle voltage output)header then col.4(MAX VOUT)header then col.5(MIN VOUT) as i said this is perform before the loop with no pr
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Attachments:
test1.txt ‏1 KB

onitoring a voltage and storing it to the same file under the associated header...What I'm having problems doing is after the loop is completed I need to write the MIN\MAX values of the voltage that was monitored in the "While Loop" once it completes. I juThis can become hard depending on how much data you will be writing. If you could wait and write the data all at one at the end of the while loop it becomes easier. The problem is that when you write a file it writes it in rows of data not columns. I will attach an example (LabVIEW 6.0) that demonstrates how to do this. It is a hard to describe in text. Basically I create the new columns of data and write empty strings to them on each iteration of the while loop except for the first iteration. The first iteration I write a Max? and Min? into the column information. After the while loop is completed I search the array for Max? and Min? and replace it with the appropriate min and max values.
Attachments:
append_column.vi ‏47 KB

JSTL While loop quick question

Hi,
I have a hashmap that contains the keys "number1", "number2" etc.... I want to loop through as long as the next key is not null, e.g.
// Assume nextKey is the string "number1" and counter is 1
while (myMap.get(nextKey) != null) {
   // do something
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   nextKey = "number" + counter ;
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Cheers.

The easiest way to do this is to use the <c:forEach> tag providing your map as the 'items' attribute.
Each iteration exposes an object of type Map.Entry which is one key-value pair in your underlying Map object. You can then use the getKey() and getValue() methods on the exposed Map.Entry object.
<c:forEach items = "myMap" var = "eachEntry">
     Key is ${eachEntry.key}
     Value is ${eachEntry.value} <br>
</c:forEach>If you have to supply the keys yourselves (in the above example, both the key and the value were discovered dynamically), then you still use the forEach tag.
However in this scenario what you need is a loop that iterates a fixed number of times equal to the size of the map.
For this you use the jstl function taglib. For example, the below post would output the size of the map.
<%@taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn"%>
${fn:length(myMap)}You use the begin and end attributes of the forEach loop to loop a fixed number of times. The varStatus attribute provides a counter inside the loop. Thus
<c:forEach begin = "0" end = "1" varStatus = "status">
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</c:forEach>would cause the loop to iterate twice printing Counter :1 Counter :2.
Finally you need to set an attribute whose value is appended with the counter to evaluate the key.
Combining all of these, your code would be
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<c:forEach begin="0" end = "${fn:length(myMap)}" varStatus="status">
     <c:set var = "nextKey" value = "${key}${status.count}"/>
     ${myMap[nextKey]}
</c:forEach>Does that help?
ram.

Beginner Question: Won't execute index to nested while loop

Problem:
I have a nested while loop inside a for loop. The for loop runs over and over from 0 to 587. I want the while loop to only execute when the for loop hits 587 by means of a continue condition which is on when 587 = [ i ], the for loop iteration number. However when I try to change the value sent to the while loop from 588 none of the probes execute. This is bad because the index only runs from 0 to 587 and never equals 588.
Context:
This is for real time video analysis. Trying to convert a 658 x 492 color video feed frame by frame into low resolution grayscale video. With this index error the output is currently the top left 1/4 of the image, repeated in a 2x2 grid on the image display.
The VI is attached. I'm very appreciative of your thoughts on this.
Attachments:
Bin.vi ‏237 KB

The for loop is responsible for processing a frame. At the completion of the execution of [ i ] from 0 to 587, the replace array VI outputs the final product of the frame. So every time [ i ] = 587, the replace array VI needs to send its array to the arraytoimage, which in turn must send the image to the image display.
I got rid of the while loop and replaced it with the case structure.
Maybe the problem is with the false case of the case structure? I want to continue outputting the same image for the next [0, 586] each time after it sends an updated image on the [ i ] = 587 iteration.
Attachments:
Bin.vi ‏238 KB

Can not pass data after while loop

Hello.
I have created a VI for my experiment and am having problem passing data outside a while loop to save on an excel file. The VI needs to first move a probe radially, take data at 1mm increment, then move axially, take data radially at 1mm increment, then move to the next axial position and repeat. It would then export these data to an excel file. The VI is a little complicated but it's the only way I know how to make it for our experiment. I have tested it and all the motion works correctly, however I can not get it to pass the data after the last while loop on the far right of the VI where I have put the arrows (Please see the attached VI ). Is it because I'm using too many sequence, case, and while loops? If so, what other ways can I use to make it export data to the excel file?
Any help would be appreciated.
Thank you,
Max
Attachments:
B.Dot.Probe.Exp.vi ‏66 KB

Ummmm .... gee, I'm not even sure where to begin with this one. Your VI is well .... ummmm... You have straight wires! That's always nice to see. As for everything else. Well... Your fundamental problem is lack of understanding of dataflow programming. What you've created is a text program. It would look fantastic in C. In LabVIEW it makes my heart break. For a direct answer to your question: Data will not show up outside a while loop until the while loop has completed. This means your most likely problem is that the conditions to stop that specific loop are not being met. As for what the problem is, I don't even want to start debugging this code. Of course, one way to pass data outside of loops is with local variables, and hey, you seem to be having so much fun with those, what's one more?
This may sound harsh, and perhaps be somewhat insulting, but the brutal truth is that what I would personally do is to throw it out and to start using a good architecture like a state machine. This kind of framework is easy to code, easy to modify, and easy to debug. All qualities that your code seems to lack.
Message Edited by smercurio_fc on 08-17-2009 10:00 PM

Why writes LabVIEW only every 2 seconds the measured Value to a Excel (In a while loop with 100 ms tact)?

Hi everybody,
I use the myDAQ to measure speed, ampere, and voltage of a battery driven motor. (For Current measurement, i use a Sensor which outputs a 0-10 V signal). I placed all DAQ-Assitants in a while loop with a [Wait until next ms multiple] clock and set a value of 100 ms. I thougt, Labview will now write into my text file 10 times a second all values. In fact, as you can see in the attached text file, Labview only writes in a unsteady interval of 1-2 seconds a value, which is too less.
The question: Did I do anything wrong, how can you create VI that writes you lets say 10 values a second into text file? Or is simply the DigitalMultimeter input of the myDAQ not able to sample a rate of 10 Hz? I couldn´t find any information in the specification handbook about the sample rate of the DMM?
If anyone can help me would be great! Thanx a lot, Markus
Attachments:
Measure Speed+Current+Voltage into Excel.vi ‏175 KB
Test7.txt ‏1 KB

File I/O is not very efficient. I recommend that you do you file logging in a parallel task. Have one task do your data acquision. This task would then pass the data to be logged to the logging task via a queue. That way your file operations do not impact your data acquision. Also, express VIs are not very efficient. You would be better off accessing that directly using the DAQ VIs. The express VIs contain lots of steps that do not need to be done every time you call it such as initializing the device.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

How can I reset the value of an indicator in a while loop, from another synchronous while loop?

I am running 2 synchronous while loops, one which is keep track of time, and the other is measuring periods. In the while loop that is measuring periods, I have a boolean indicator displaying whether the signal is on or off. My problem is that when the signal is off, the VI I use to measure the periods is waiting for the next signal, and displays the boolean value from the previous period measurement. While this VI is waiting, I want the indicator to display false and not the value from the last iteration of the loop.
I am using LV 5.1 for MAC.

Two things you can try:
In preface to the first, the most common (perhaps ONLY) use of local variables should be in transferring data between parallel loops. This is a matter of discipline, and creates programs that are easier to understand, take less time and memory, and are just plain cleaner. Having said that, to transfer data between loops, use a local variable.
Second solution: Instead of setting the value to false, just hide the indicator in question by using control references (property nodes for prev. version of LabVIEW). Control references are a great way to control items on a dialog or HMI screen.

Sir i am using datasocket read ,i am communicating with java but my problem is that bcz im using while loop to see if value has changed my labview consumes all the processors time ,sir i want a event like thing so that while loop is not in continuous loop

sir i have given lot of effort but i am not able to solve my problem either with notifiers or with occurence fn,probably i do not know how to use these synchronisation tools.

sir i am using datasocket read ,i am communicating with java but my problem is that bcz im using while loop to see if value has changed my labview consumes all the processors time ,sir i want a event like thing so that while loop is not in continuous loopHi Sam,
I want to pass along a couple of tips that will get you more and better response on this list.
1) There is an un-written rule that says more "stars" is better than just one star. Giving a one star rating will probably eliminate that responder from individuals that are willing to anser your question.
2) If someone gives you an answer that meets your needs, reply to that answer and say that it worked.
3) If someone suggests that you look at an example, DO IT! LV comes with a wonderful set of examples that demonstate almost all of the core functionality of LV. Familiarity with all of the LV examples will get you through about 80% of the Certified LabVIEW Developer exam.
4) If you have a question first search the examples for something tha
t may help you. If you can not find an example that is exactly what you want, find one that is close and post a question along the lines of "I want to do something similar to example X, how can I modify it to do Y".
5) Some of the greatest LabVIEW minds offer there services and advice for free on this exchange. If you treat them good, they can get you through almost every challenge that can be encountered in LV.
6) If English is not your native language, post your question in the language you favor. There is probably someone around that can help. "We're big, we're bad, we're international!"
Trying to help,
Welcome to the forum!
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

While loop and data acquisition timing worries

Hello everyone,
I apologize in advance if this is a silly question, but I could not find the answer around here.
I have made a VI to record continuously from 64 analog channels at a 5kHz sampling rate. I then stream this data to a tdms file. The data acquisition and write functions are in a while loop.
I the same loop, I have a bunch of other loops, that each run on their own wait timers to help limit the amount of memory they take up. I am now worried that this may somehow affect my data acquisition timing.
If I put a bunch of timed loops within another loop, does the outer loop run at the same pace as the slowest of the inner loops? And could that mess up my sampling rate?
I have attached my VI, in case what I just wrote makes no sense at all.
Thanks for any tips...
Attachments:
Record_M8viaDAQv3.vi ‏237 KB

Well, looking at your code you will only write to your TDMS file one time. You have multiple infinite loops within the main/outer loop. That means that the main loop will only run a single iteration because it cannot complete an iteration until all code within it completes. With at least two infinite loops inside the loop it will never complete. Not too mention the only way to stop your code is to hit the stop/abort button. NOt a very good way to stop your code. As someone once said using the abort to stop your code is like using a tree to stop your car. It will work but not advised.
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Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

What's wrong with this while loop?

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System.out.println("what about here?");
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i've got the problem sort out, eventually. there was actually nothing wrong with the while loop. it was caused by a typo in databse, instead of having Brisbane, i typed Bisbane. The single letter r cost me more than 6 hours to figure it out. it was such a painful feeling while i realized i made a such stupid mistake.
by the way, as jnw777 mentioned, output rs.next() info instead of the test line. i did try it, however i didnt realize even System.out.println(rs.next()) would cause the cursor move down one row from its current position. so, plus the original while(rs.next()) statement, it was moving the cursor two rows down at a time! And i just couldnt think of this caused me the fact i was only getting the even number row of the ResultSet while i was sniffing the bug from a class with 700+ lines of code. I was so excited and just couldnt stop yelling at the moment i got over it! That was a damn execiting moment...
now, i am wondering if anyone in this wonderland would like to share his/her stories.

How do I create a start/stop button for each separate while loop within my program, when each of them does a different task?

I have a multimeter VI with separate while loops to accomplish the different tasks of reading voltage, current, etc. Each while loop has a stop button, but I need a button that will have to be pressed in order for the while loop to even start. I tried putting another while loop around the present one, but it still has to run once before it will stop. I want the user to have to press the button before it runs, because they interfere with each other.
I am just learning so patience and your kind assistance is greatly appreciated!
ElectroKate

iZACHdx wrote:
Hello,
I'm not entirely clear with everything you have going on and what you want your final functionality to be, but you can use sequence structures to prevent a loop from starting until the user presses a button like this:
-Zach
I have to ask, why is an NI employee using examples using sequence frames? The same thing could be accomplished using data flow by simply wiring the value of the first stop button out of teh first while loop and connecting it to the second loop. This would then use data flow to control the sequence. Why show new users bad programming methods?
As to the original question I would concur with altenbach on using an event structure.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

How can I make a while loop wait for input boolean?

Hi.
I'm trying to control a robotic arm with labview for my undergrad dissertation, and I have a decent polar coordinate control panel made, but there is one problem; it checks for changes in the coordinates every five seconds, while I want it to only check on the touch of a button (ie, go!, I've changed your coordinates!). The changes are calculated with a while loop comparing the last value of theta, x and z in a while loop with the current one. I can't find a way of putting that into a case structure. If there is a way of making the while loop progress at the push of a button, I think it would work. The VI's attached below.
Thanks in advance for any help.
Cathal Scanlon
ps, sorry about the mess, I'm going to reorganise the while loop into 2 if I can get the control button working.
Message Edited by CatScan on 02-08-2007 02:45 PM
Attachments:
Polar coord assignment1.vi ‏142 KB

Have you tried using an event structure? To use one, right click on the structure to add an event. Set the event as whatever button you wish to monitor and set the event to "Value Change". If you put this inside a while loop any time the button is pressed, the event structure will run the contents inside the loop. There are a number of options to have the event structure activate.
*** Warning! I'm probably the last guy you want answering your labVIEW questions, but I figured I might be able to help.

Stupid WHILE loop question

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