Arrays inside newtypes
Arrays inside newtypes are slightly different from normal arrays (and you cannot put lists inside newtypes).
You must still give the array a name and type, the same way as all the other fields in a newtype, and you must not
use the Dim command. Also, you must use square brackets for the array index,
not parenthesis (rounded brackets). Finally, the index you specify when you create the array is not the maximum index
number you can use for the array (as it is with normal arrays), it is the maximum number of items in the array.
Using the arrays inside the newtype is the same as using any other field of a newtype, except you specify
the index of the array in square brackets:
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NEWTYPE.arrayexample
values.w[10] ; We can access items in the array with indexes 0...9
End NEWTYPE
DEFTYPE.arrayexample foo
foo\values[5] = 69 ; OK
foo\values[10] = 123 ; Error!!!
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Of course, apart from those differences, arrays inside newtypes are exactly like normal arrays and other fields
of newtypes. That means they can be arrays of newtypes themselves, and you would access them as shown above
followed by '\field', just like normal arrays.
Sizeof
The SizeOf command is a useful one for getting sizes of newtypes (or basic types if you wish)
and also getting the offset (in bytes) from the start of the newtype to a specific field. So far, this offset has
shown to be useful for the array and list sort commands, but there are many other uses. The structure of this command
is 'SizeOf.type' and optionally 'SizeOf.type\field' and it will return the size of the type or the offset for the field
in the number of bytes:
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NEWTYPE.arrayexample
values.w[10] ; We can access items in the array with indexes 0...9
End NEWTYPE
NEWTYPE.person
; Defining some fields in this newtype
name$ ; Person's name
age.w ; Their age in years
height.q ; Height in metres
; Defining fields without the type - month and year are defined as .w (same as first field)
day.w : month : year ; Date of birth
End NEWTYPE
NPrint SizeOf.w ; Size of a word type
NPrint SizeOf.s ; Shows only the base size of a string, that is the 4 bytes which all strings require
NPrint SizeOf.arrayexample ; Gives the total size of the newtype, which is 5*2 (size of array * size of each array item)
NPrint SizeOf.person\height ; Gives offset of the height field (= size of all fields before it)
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USEPATH
This command can be used to save yourself some typing. It allows you to specify a piece of a variable path (with newtype
access in it) and whenever the compiler after that sees a variable which starts with the \ character (i.e. if you miss
off the variable part from the front) it will automatically expand it to include the path you specify in the USEPATH
command. For example:
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NEWTYPE.person
; Defining some fields in this newtype
name$ ; Person's name
age.w ; Their age in years
height.q ; Height in metres
; Defining fields without the type - month and year are defined as .w (same as first field)
day.w : month : year ; Date of birth
End NEWTYPE
DEFTYPE.person foo ; Create our variable
foo\name = "Hugh" ; Jass ;)
foo\age = 24 ; years old
foo\height = 1.8 ; metres tall
USEPATH foo
NPrint \name," is ",\height," metres tall."
; In the above line, the compiler automatically took the path we specified in
; the USEPATH command (in this case, 'foo') and placed it in front of the variables
; we accessed starting with the \ character. This meant we were accessing the fields
; foo\name and foo\height in the NPrint line
MouseWait
End
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Initialising a whole newtype in one command
In the previous example, it took three lines to initialise three fields of the variable foo. There is a shortcut which
you can use to initialise the contents of a newtype in one statement. You must initialise the fields in order, and
you cannot skip any fields in the middle of those you are initialising. The way to do it is to start off with the
usual assignment of a value to a field, and then put a comma followed by the value for the next field, and so on,
for all the fields you want to initialise. You can start from any field, but you must then carry on in order. So,
we could have made the line in the above example look like this:
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; Initialising all the fields from the above example in one statement
foo\name = "Hugh",24,1.8
NPrint foo\name," is ",foo\age," years old and ",foo\height," metres tall."
foo\day = 25,12,1977 ; Initialises three other fields; you can start from any field but always initialises in order
NPrint "Date of birth: ",foo\day,"/",foo\height,"/",foo\year
MouseWait
End
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Unions
You are very unlikely to see these, so feel free to skip this part as it is fairly complex, compared to the rest
of the info presented here.
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