Symbian中如何读入一行文本的类TFileText--SDk

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 » Symbian OS v9.2 » Symbian OS reference » C++ component reference » Base F32 » TFileText

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Location: f32file.h
Link against: efsrv.lib

Class TFileText

class TFileText;

Description

Reads and writes single lines of text to or from a file.

Members

Defined in TFileText:
Read(), Seek(), Set(), TFileText(), Write()

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Construction and destruction

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TFileText()

IMPORT_C TFileText();

Description

Default constructor.

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Member functions

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Set()

IMPORT_C void Set(RFile &aFile);

Description

Sets the file to be read from, or written to.

This function must be called before Read(), Write() or Seek() can be used.

Parameters

RFile &aFile The file to be used. Must be open.

See also:

• TFileText::Read
• TFileText::Write
• TFileText::Seek

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Read()

IMPORT_C TInt Read(TDes &aDes);

Description

Reads single line text record into the specified descriptor.

The read operation begins at the current file position, and ends when a line delimiter character is read; a record has a maximum length of 256 characters.

If the maximum length of the descriptor is insufficient to hold the record, the function returns KErrTooBig and the descriptor is filled to its maximum length.

If Read() is called when the current position is the end of the file (that is, after the last line delimiter in the file), KErrEof is returned, and the length of the buffer is set to zero.

Parameters

TDes &aDes On return, contains the single record read from the file. Any previous contents are overwritten.

Return value

TInt KErrNone if successful, otherwise one of the other system-wide error codes.

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Write()

IMPORT_C TInt Write(const TDesC &aDes);

Description

Writes the contents of a descriptor to the end of a file.

A line delimiter is appended to the descriptor, and the current file position is set to the new end of file.

If the descriptor contains one or more paragraph delimiters, Read() will treat the contents of the descriptor as more than one record.

Parameters

const TDesC &aDes The descriptor content to be appended to the file.

Return value

TInt KErrNone if successful, otherwise one of the other system-wide error codes.

See also:

• TFileText::Read

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Seek()

IMPORT_C TInt Seek(TSeek aMode);

Description

Seeks to start or end of file.

It is only necessary to call this function before using Read() because Write() always seeks to the end of the file before writing.

Parameters

TSeek aMode ESeekStart to seek to the start of the file; ESeekEnd to seek to the end.

Return value

TInt KErrNone if successful, otherwise one of the other system-wide error codes.

Panic codes

FSCLIENT 5 if aMode is neither ESeekStart nor ESeekEnd.

See also:

• TFileText::Read
• TFileText::Write

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