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Compare operands of type STRUCT

Engineering 🇬🇧
PatrickT
2015-09-21
2015-09-22

  • PatrickT - 2015-09-21

    The following Help section for Data Type > Structure implies that it is possible to compare structures:

    "If the target system supports the data type, as from compiler version >= 3.5.7.0 you can compare operands of type STRUCT (structure). Example: IF (stStruct1 := stStruct2) THEN...." .

    (I assume this is a typo and should read IF (struct1 = struct2) THEN ...)

    Using Control Win V3 Version 3.5.7.10, I have:

    TYPE TestDUT :
    STRUCT
    MyInt: INT;
    END_STRUCT
    END_TYPE

    VAR
    struct1: TestDUT;
    struct2: TestDUT;
    testBool: BOOL;
    END_VAR

    IF (struct1 = struct2) THEN
    testBool := TRUE;
    END_IF

    This generates the error:
    Cannot compare type 'TestDUT' with type 'TestDUT'

    Have I made an error or is this feature not supported on the target system?

     

  • learnetk - 2015-09-22

    Hi
    not sure that you could still compare structure directly. But you could do it with pointers, using the Sysmemcmp function in library Sysmem. 

    pstruct1: POINTER TO BYTE;
pstruct2: POINTER TO BYTE;

   pstruct1 := ADR(struct1);
   pstruct2 := ADR(struct2);

    IF sysmemcmp(pstruct1,pstruct2, SIZEOF(struct1)) <> 0 THEN
    testBool := TRUE;
    ELSE
    testBool := FALSE;
    END_IF

    something as above

     
    👍
    1

  • PatrickT - 2015-09-22

    Great, that's exactly what I need, thanks.

     

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