This topic describes how to reading transfer data from a file to a descriptor, and writing transfers data from a descriptor to a file.
Reading transfers data from a file to a descriptor, and writing transfers data from a descriptor to a file.
// Open file1 _LIT(KMyFile,"c:\\documents\\file1"); RFile myFile; User::LeaveIfError(myFile.Open(fs,KMyFile,EFileShareExclusive|EFileWrite )); // Write to current file position: start of file _LIT8(KWriteBuf,"write data"); myFile.Write(KWriteBuf); // Read from position 0: start of file TBuf8<6> readBuf1; myFile.Read(0,readBuf1); // readBuf1 is now "write " // Read from current position TBuf8<4> readBuf2; myFile.Read(readBuf2); // readBuf2 is now "data"
In all cases, the file data is treated as binary and byte descriptors are used (TDes8, TDesC8). Thus, file operations are not dependent on the Unicode/non-Unicode build variant.
There are several variants of both Read() and Write() . The basic Read(TDes8& aDes) and Write(const TDesC8& aDes) are supplemented by variants allowing the descriptor length to be overridden, or the seek position of the first byte to be specified, or asynchronous completion, or any combination.
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