Element alignment

By default, the elements are tightly aligned in memory, one after each other.

This approach is memory efficient, yet in some cases, you need an alternative:

when in need of optimizing UDT element access speed from low-level code

for compatibility with another language

You can control the alignment via the alignment modifier. It can take 3 different values:

byte, for 1 byte alignment (default)
word, for 2 byte alignment
dword, for 4 byte alignment

In case you want to elements aligned to 4 byte steps, you might consider using DWORD modifier.

Let's have a look at this example:

TYPE RGBColor
  R AS BYTE
  G AS BYTE
  B AS BYTE  
END TYPE

By default, the size of RGBColor will be 3 bytes, as you can verify with SizeOf:

msgBox SizeOf(RGBColor)

3 elements, each 1 byte in size.

To apply 32bit alignment, use DWORD modifier:

TYPE DwordAlignedRGBColor DWORD
  R AS BYTE
  G AS BYTE
  B AS BYTE  
END TYPE

This means that R, G and B elements will still be of byte data type, however, their element offset will change to 4 byte jumps.

You can verify it easily:

DIM colorNormal  AS RGBColor

msgbox strFormat$("The offset of .R is {1}, .G is {2} and .B is {3}",
                  UDT_ElementOffset(colorNormal.r),
                  UDT_ElementOffset(colorNormal.g),
                  UDT_ElementOffset(colorNormal.b))

DIM colorAligned AS DwordAlignedRGBColor
                  
msgbox strFormat$("The offset of .R is {1}, .G is {2} and .B is {3}",
                  UDT_ElementOffset(colorAligned.r),
                  UDT_ElementOffset(colorAligned.g),
                  UDT_ElementOffset(colorAligned.b))