ST search an array for a value

[MikeLind]

Hi I new to ST programming and I am trying to figure out how I can search an array for an value (3).

I want TEST to go high if eg trayArray[6] = 3 and low if none of the trayArray[j] is 3.


VAR
TEST: BOOL;
trayArray: ARRAY [0..15] OF INT;
j: INT;
END_VAR



FOR j:= 0 TO 15 DO;

IF trayArray[j] = 3 THEN
TEST := TRUE;
ELSIF
trayArray[j] <> 3 THEN
TEST := FALSE;
END_IF

END_FOR



Is what i got but it aint working :s any suggestions? tried google already

 

[JesperMP]

Your code should work.
Your code wont work because even if a match is found an test is set true, at the next array element that does not match the same variable is set back to false.
This will work:

temp_test:=FALSE;
FOR j:= 0 TO 15 DO;
  IF trayArray[j] = 3 THEN 
    temp_test := TRUE;
  END_IF ;
END_FOR ;
test := temp_test ;

Is you array initilized ?
You can try to add this line
trayArray[1] := 3;

 

[MikeLind]

Your code should work.
Your code wont work because even if a match is found an test is set true, at the next array element that does not match the same variable is set back to false.
This will work:

temp_test:=FALSE;
FOR j:= 0 TO 15 DO;
  IF trayArray[j] = 3 THEN 
    temp_test := TRUE;
  END_IF ;
END_FOR ;
test := temp_test ;

Is you array initilized ?
You can try to add this line
trayArray[1] := 3;

Jesper you are the man!

Is this the optimal way to go about the search for number 3 or is there a more "simple" way to get the same result. I always try to keep the code as short as possible

 

[JesperMP]

You could remove the temp_test and use test directly.
I use the temporary variable so that test variable doesnt "flicker". For example, if the test variable were displayed on an HMI, the flickering would confuse the operator.

 

[MikeLind]

Ok thanks a bunch have a nice weekend

 

[drbitboy]

I don't know ST very well but something like this may be simpler:

j := 0;
while j < 16 do;
  if array[j] = 3 then
    break;
  end_if;

  j := j + 1;

end_while;
test := j < 16;

Does ST have [while...do] and [break]? If it has BREAK, then maybe it can break out a FOR loop:

for j := 0 to 15 do;
  if array[j] = 3 then
    break;
  end_if;

end_for;
test := j < 16;

Also, it would be nice if the IF did not require THEN and END_IF:

  if array[j] = 3 break;

 

[L D[AR2P#0.0]]

Here's another alternative with no loops or ifs (TIA V16)

 

[L D[AR2P#0.0]]

or this:

 

[drbitboy]

or this:

Ooh, pretty, shiny.


better than sh...y and priny.

 

[ndzied1]

Does ST have [while...do] and [break]? If it has BREAK, then maybe it can break out a FOR loop:

for j := 0 to 15 do;
  if array[j] = 3 then
    break;
  end_if;

end_for;
test := j < 16;

Also, it would be nice if the IF did not require THEN and END_IF:

  if array[j] = 3 break;

Not break but there is an EXIT command that is used in the same way.
You do need the THEN/END_IF

 

[chelton]

Break loop if trayarray =3.

i := 0;
WHILE trayarray[i] <> 3 AND i < 15 DO
	i:=i +1;
END_WHILE;
test:=trayarray[i]=3