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66 CHAPTER 3. LANGUAGE<br />
ÖÑ ´ÅÖÙظ ³ÑÖÙسµ<br />
ØÖ×ÓÐ ´ÅÖÙظ ÊÓÒ¸ ½¼¸ ¾µ<br />
Ö× ℄<br />
ÓÖ ÊÙ× ½ ØÓ ¼ Ý ½<br />
ÐØÓÒÖÐ ´ÊÓÒ¸ ÊÓÒÐØÓÒ¸ ÊÙ×µ<br />
ÖÒØÖ ´ÊÓÒÐØÓÒ¸ Ö¸ ÊÓÛ¸ ÓÐÙÑÒµ<br />
Ö×ÊÙ×¹½℄ Ö<br />
ÒÓÖ<br />
Please note that first the variable Ö× has to be initialized in order to avoid a runtime error.<br />
In the example Ö× is initialized with the empty tuple (℄). Instead of Ò×ÖØ the operator<br />
××Ò with tuple concatenation<br />
Ö× Ö׸Ö℄<br />
could be used, because the element is appended at the back of the tuple.<br />
More examples can be found in the program ××ÒºÚ.<br />
3.5.3 Basic Tuple Operations<br />
A basic tuple operation may be selecting one or more values, combining tuples (concatenation)<br />
or reading the number of elements.<br />
ظØ℄<br />
Ø<br />
Ø℄<br />
Ø℄<br />
concatenation of tuples<br />
number of elements<br />
selection of an element<br />
selectionof(apartof)atuple<br />
Table 3.7: Basic operations on tuples<br />
The concatenation accepts one or more variables or constants as input. They are all listed<br />
between the brackets, separated by commas. The result again is a tuple.<br />
Ø ½¸Ø ¾ ℄ is the concatenation of tuple Ø ½ and Ø ¾ .Example:<br />
¸³ÌÜس℄¸º℄℄ ¸³ÌÜس¸º℄<br />
So even the following holds: Ø℄℄ Ø℄ Ø.<br />
Ø returns the number of elements of a tuple. The indices of elements range from zero to the<br />
number of elements minus one (i.e., ع½). Therefore, the selection index has to be within this<br />
range. 2<br />
ÌÙÔРν¸Î¾¸Î¿¸Î℄<br />
ÓÖ ¼ ØÓ ÌÙÔй½ Ý ½<br />
ÛÖØ×ØÖÒ ´ÐÀÒиÌÙÔÐ℄·³Ò³µ<br />
ÒÓÖ<br />
2 Please note that the index of objects (e.g., ×ÐØ ÓØ) ranges from 1 to the number of elements.<br />
<strong>HDevelop</strong> / 2000-11-16