請問個用法TMemoryStream->Seek |
答題得分者是:RaynorPao
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jumpsister
一般會員 發表:5 回覆:3 積分:1 註冊:2004-06-04 發送簡訊給我 |
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RaynorPao
版主 發表:139 回覆:3622 積分:7025 註冊:2002-08-12 發送簡訊給我 |
引言: 小弟這幾天在看檔案的I/O; 爬文發現TMS之好用..... TMS->Seek(int Offset, Word Origin);..... BCB help上面寫int<0代表從我load的資料後面開讀取資料(是這樣嗎) 那後面是什麼意思 Word Origin? 那如果我想從資料後面只讀取一小部分..那應該怎麼使用這用法 感謝各位大大之指教...... jumpsister 你好: (1)有關這一點,在 BCB Help 裡面都說得非常清楚,建議你仔細看看 TCustomMemoryStream::Seek Moves the current position of the stream by Offset bytes, relative to the origin specified by Origin. virtual int __fastcall Seek(int Offset, Word Origin); Description Use Seek to move the current position within the memory stream by the indicated offset. Seek allows an application to read from or write to a particular location within the Memory associated with the memory stream. If Offset is a negative number, the seek is backward from the specified origin. The following table shows the different values of Origin and their meanings for seeking. Value Meaning ---------------------------------------------------------------------- soFromBeginning Offset is from the beginning of Memory. Seek moves to the position Offset. Offset must be >= 0. soFromCurrent Offset is from the current position. Seek moves to Position + Offset. soFromEnd Offset is from the end of Memory. Offset must be <= 0 to indicate a number of bytes before the end of the memory buffer. Seek returns the new value of the Position property. Note: Seek does no error checking on the value provided for Offset. Do not call seek with an offset that would move the current position less than 0 (before the start of Memory) or greater than Size (beyond the end of the memory buffer). (2)請參考以下的範例程式碼 (讀取檔案最後 5 個 byte 為例) >>>>>>>>>>> > >> < src="http://delphi.ktop.com.tw/loadfile.php?TOPICID=10003806&CC=223734"> -- Enjoy Researching & Developing -- 發表人 - RaynorPao 於 2004/07/12 14:04:10
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jumpsister
一般會員 發表:5 回覆:3 積分:1 註冊:2004-06-04 發送簡訊給我 |
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