number casting to type

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Dear all,

I needed to cast numbers to specific types (i.e. int16, uint16, etc.) so I wrote the following code, which may be an indication of a bug or an oversight on my behalf. Could you please verify either way?

structure struct_type
    char byte
    uchar ubyte
    int16 int16
    uint16 uint16
    int32 int
    int32 int32
    uint32 uint
    uint32 uint32
    float float
    float flt16
    double double
    double flt32
endstructure
 
function cast(var, type)
    variable var
    string type
    
    struct struct_type r
    
    strswitch(type)
        case "byte":
            r.byte = var; var = r.byte
            break
        case "ubyte":
            r.ubyte = var; var = r.ubyte
            break
        case "int16":
            r.int16 = var; var = r.int16
            break
        case "uint16":
            r.uint16 = var; var = r.uint16
            break
        case "int":
        case "int32":
            r.int32 = var; var = r.int32
            break
        case "uint":
        case "uint32":
            r.uint32 = var; var = r.uint32
            break
        case "flt16":
        case "float":
            r.float = var; var = r.float
            break
        case "flt32":
        case "double":
            r.double = var; var = r.double
            break
    endswitch
    
    return var
end


And compare the results of:
•variable a
•a = cast(-5, "uint16"); print a
  65531
•a = cast(-5, "uint32"); print a
  0


I would expect the second call (a = cast(-5, "uint32")) to set variable a to: 4294967291, the 2 complement of -5.
Looks like a bug. If you can use IP7 I'd use matrixop


•make/d/N=1 data = -5
•matrixop/o result = uint16(-5)
•print result
  result[0]= {65531}
•matrixop/o result = uint32(-5)
•print/D result
  result[0]= {4294967291}

January 17, 2018 at 01:24 pm - Permalink

thomas_braun wrote:
Looks like a bug. If you can use IP7 I'd use matrixop


•make/d/N=1 data = -5
•matrixop/o result = uint16(-5)
•print result
  result[0]= {65531}
•matrixop/o result = uint32(-5)
•print/D result
  result[0]= {4294967291}


Thanks for letting me know about this feature in IP7. It is way more pleasant to the eye like that.

While we are on the topic, does the uint32 struct field also return/ store 0 in the case of -5 in IP7 as well?

best,
_sk

January 18, 2018 at 02:34 am - Permalink