Extracting number from string

Engineering 🇬🇧
kallileo
2019-07-23
2019-07-26

  • kallileo - 2019-07-23

    I read a text file with saved parameters which has the following structure:

    123
    492
    500
    6091
    etc

    The resulting string looks like the following:
    '123$R$N492$R$N500$R$N6091'

    How can I extract all the numbers without the special characters from the string and assing them to an INT array?

     

  • dFx

    dFx - 2019-07-23

    split your string using the special chars ( Cr Lf ) into a string array.
    Then cast each string item to the desired datatype (int, real …)

     

  • kallileo - 2019-07-23

    The following code worked for me:

    PROGRAM PLC_PRG
VAR
   parameters: ARRAY[1..4] OF INT;
   splitString : BOOL;
   fileString : STRING := '123$R$N492$R$N500$R$N6091$R$N';
   arINT1 : INT;
   first : STRING;
   fileStringDel : STRING;
   index : INT := 1; 
END_VAR

    IF splitString THEN
   FOR index:=1 TO 4 DO
      arINT1 := FIND(fileString,'$R$N');
      first := LEFT(fileString,arINT1-1);
      fileString := DELETE(fileString,arINT1+1,1);
      parameters[index]:=STRING_TO_INT(first);
   END_FOR
   splitString := FALSE;
   index := 0;   
END_IF

    Unfortunately the maximum editable string size is 255 characters so not many parameters can be saved into one string.

     

  • Lo5tNet - 2019-07-24

    Try looking at StringUtils library. You can do something like this to have way more than 255 characters:

    PROGRAM ParameterExtractor
VAR
    sLongString : STRING(1024) := '01234567890$R$N1234567890$R$N2345678901$R$N3456789012$R$N4567890123$R$N5678901234$R$N6789012345';
    sShortString : STRING;
    aParameters : ARRAY[0..MAXPARAMETERS] OF ULINT;
    sSplitChars : STRING := '$R$N';
    iSplitLocation : INT;
    iCount : INT := 0;
END_VAR
VAR CONSTANT
    MAXPARAMETERS : INT := 9;
END_VAR
//Loop through string until there is no string left or array has hit its limits
    WHILE StrLenA(pstData:= ADR(sLongString)) > 0 DO
        //Find location of first break point
        iSplitLocation := StrFindA(pst1:= ADR(sLongString), pst2:= ADR(sSplitChars), uiSearchStart:= 1) - 1;
        
        //If there is no break point found then set location to size of string
        IF iSplitLocation = -1 THEN
            iSplitLocation := DINT_TO_INT(StrLenA(pstData:= ADR(sLongString)));
        END_IF
      
        //Copy the part of the string that is needed for the parameter.
        StrMidA(
                pst:= ADR(sLongString), 
                uiInputBufferSize:= SIZEOF(sLongString), 
                iLength:= iSplitLocation, 
                iPosition:= 1, 
                pstResult:= ADR(sShortString), 
                uiResultBufferSize:= SIZEOF(sShortString));
        //Make sure string is not empty before using up an array spot.
        IF StrLenA(pstData:= ADR(sShortString)) > 0 THEN
            aParameters[iCount] := STRING_TO_ULINT(sShortString);
            iCount := iCount + 1;
        END_IF
        //Remove copied components from long string
        StrDeleteA(pby:= ADR(sLongString), iLength:= (iSplitLocation + 2), iPosition:= 1);
        //Check to see if more parameters can fit in array. If not exit loop
        IF iCount > MAXPARAMETERS THEN
            iCount := 0;
            EXIT;
        END_IF 
    END_WHILE
     

  • kallileo - 2019-07-25

    @Comingback4u

    You code looks much better than mine.
    So by using this library it's possible to manipulate strings longer than 255 characters?

     

  • Lo5tNet - 2019-07-26

    Yes, In the above example I define the size of the string by declaring "sLongString : STRING(1024) := ..." so we are at 4x the standard size of STRING. With the StringUtil library you specify the size of the buffer using the SIZEOF(sLongString) so you aren't limited to the 255. You can go much higher than 1024 but this was just for example.

     

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