I have been experimenting with arrays of strings.
Consider the following static string array code:
string mystring[10]
mystring[5] = "Bob"
print "[",mystring[5],"]"
The result prints [Bob] as expected. :)
Now consider dynamic array code:
pointer parray
parray = new(string,10) ' Allocate array.
' ZeroMemory(array, elements * size)
ZeroMemory(#<string>parray, 10 * 255)
#<string>parray[5] = "Bob "
print "[",#<string>parray[5],"]"
print len(#<string>parray[5])
The result prints "B" with a length of 1. Why? ???
Now consider:
#<string>parray[5,5] = "Bob "
print "[",#<string>parray[5,5],"]"
print len(#<string>parray[5,5])
delete parray
The result prints [Bob ] as desired. 8)
Is the second subscript the string length?
I am puzzled by the two subscripts. ???
Here is my complete program:
$Main
autodefine "off"
openconsole
DECLARE IMPORT,ZeroMemory ALIAS RtlZeroMemory( POINTER pvoid,INT length),INT
'$Include "waitkey$.inc"
' WaitKey.inc
Declare IMPORT, Sleep(dwmillisecs As Int)
Sub WaitKey$(Opt raw=0 As Int),String
String myinKey
Do:Sleep(100):
myinKey = InKey$(raw)
Until myinKey<>""
Return myinKey
End Sub
'
Int starttime,endtime
starttime = Timer
string mystring[10]
mystring[5] = "Bob"
print "[",mystring[5],"]"
pointer parray
parray = new(string,10) ' Allocate array.
' ZeroMemory(array, elements * size)
ZeroMemory(#<string>parray, 10 * 255)
#<string>parray[5] = "Bob "
print "[",#<string>parray[5],"]"
print len(#<string>parray[5])
#<string>parray[5,5] = "Bob "
print "[",#<string>parray[5,5],"]"
print len(#<string>parray[5,5])
delete parray
label EndItHere
endtime = Timer
endtime -= starttime
If endtime < 0 Then
endtime += 86400 ' Calculate time past midnight.
endif
Print
Print "Elapsed Time:"
Print endtime," secs."
Print
Print "Done..."
Print "Press any key to quit."
WaitKey$()
closeconsole
End
???
String arrays are actually two dimensional, you don't notice because a static array is handled automatically by the compiler, it multiplies indexes for you.
When you allocate memory the type is only used to calculate the size of the allocated block and as far as the compiler is concerned it is just a contiguous array of bytes. A pointer is just the address of memory, it does not contain the dimensions of the array. You have to do the math yourself.
#<string>parray[5]
Accesses the 5th byte of the array, not the 5th string because a pointer does not contain dimensions, just an address. In fact indexes in brackets won't do you much good with a block of memory. The correct way to do it is with the * pointer operator and some pointer math...
pointer p
p = new(string,3)
*<string>(p+0)="hello"
*<string>(p+1*255)="There"
*<string>(p+2*255)="Robert"
for x = 0 to 2
print *<string>(p+x*255)," "
next x
do:until inkey$ <> ""
delete p
The * dereference operator allows treating any value as a pointer, including the result of adding a value to a pointer.
Paul.
Thanks, Paul, for the valuable info.
Sorry about your job, but I am glad you are back.
;D