關於procedure 的小問題 |
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MidasFan
一般會員   發表：41 回覆：22 積分：12 註冊：2004-06-03 發送簡訊給我 |
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Fishman
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Help in Delphi for Out parameters:
Out parameters An out parameter, like a variable parameter, is passed by reference. With an out parameter, however, the initial value of the referenced variable is discarded by the routine it is passed to. The out parameter is for output only; that is, it tells the function or procedure where to store output, but doesn’t provide any input. For example, consider the procedure heading procedure GetInfo(out Info: SomeRecordType); When you call GetInfo, you must pass it a variable of type SomeRecordType: var MyRecord: SomeRecordType; ... GetInfo(MyRecord); But you’re not using MyRecord to pass any data to the GetInfo procedure; MyRecord is just a container where you want GetInfo to store the information it generates. The call to GetInfo immediately frees the memory used by MyRecord, before program control passes to the procedure. Out parameters are frequently used with distributed-object models like COM and CORBA. In addition, you should use out parameters when you pass an uninitialized variable to a function or procedure. Fishman
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Fishman |
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