FileAccess VB.NET Reference Documentation

FileAccess

Current Version: 9.5.0.75

API for reading and writing files, creating and deleting directories, deleting directory trees, splitting and re-joining large files, etc. This is a freeware class. The reason for its existence is that in some programming languages, file I/O API's are limited or difficult to understand/use. This API provides an identical FILE I/O API across all programming languages supported by Chilkat.

Object Creation

Dim obj As New Chilkat.FileAccess()

Properties

CurrentDir
CurrentDir As String (ReadOnly)

The current working directory of the calling process.

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DebugLogFilePath
DebugLogFilePath As String

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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EndOfFile
EndOfFile As Boolean (ReadOnly)

Returns True if the current open file is at the end-of-file.

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FileOpenError
FileOpenError As Integer (ReadOnly)

This property is set by the following methods: FileOpen, OpenForRead, OpenForWrite, OpenForReadWrite, and OpenForAppend. It provides an error code indicating the failure reason. Possible values are:

  1. Success (No error)
  2. Access denied.
  3. File not found.
  4. General (non-specific) open error.
  5. File aleady exists.
  6. Path refers to a directory and the access requested involves writing.
  7. Too many symbolic links were encountered in resolving path.
  8. The process already has the maximum number of files open.
  9. Pathname is too long.
  10. The system limit on the total number of open files has been reached.
  11. Pathname refers to a device special file and no corresponding device exists.
  12. Insufficient kernel memory was available.
  13. Pathname was to be created but the device containing pathname has no room for the new file.
  14. A component used as a directory in pathname is not, in fact, a directory.
  15. Pathname refers to a regular file, too large to be opened (this would be a limitation of the underlying operating system, not a limitation imposed by Chilkat).
  16. Pathname refers to a file on a read-only filesystem and write access was requested.

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FileOpenErrorMsg
FileOpenErrorMsg As String (ReadOnly)

The error message text associated with the FileOpenError code.

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LastErrorHtml
LastErrorHtml As String (ReadOnly)

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
LastErrorText As String (ReadOnly)

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
LastErrorXml As String (ReadOnly)

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
LastMethodSuccess As Boolean
Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of True indicates success, a value of False indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = True and failure = False.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to True. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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VerboseLogging
VerboseLogging As Boolean

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
Version As String (ReadOnly)

Version of the component/library, such as "9.5.0.63"

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Methods

AppendAnsi
Function AppendAnsi(ByVal text As String) As Boolean

Appends a string using the ANSI character encoding to the currently open file.

Returns True for success, False for failure.

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AppendText
Function AppendText(ByVal str As String, ByVal charset As String) As Boolean

Appends a string using the character encoding specified by str to the currently open file.

Returns True for success, False for failure.

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AppendUnicodeBOM
Function AppendUnicodeBOM() As Boolean

Appends the 2-byte Unicode BOM (little endian) to the currently open file.

Returns True for success, False for failure.

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AppendUtf8BOM
Function AppendUtf8BOM() As Boolean

Appends the 3-byte utf-8 BOM to the currently open file.

Returns True for success, False for failure.

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DirAutoCreate
Function DirAutoCreate(ByVal filePath As String) As Boolean

Same as DirEnsureExists, except the argument is a file path (the last part of the path is a filename and not a directory). Creates all missing directories such that filePath may be created.

Returns True for success, False for failure.

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DirCreate
Function DirCreate(ByVal dirPath As String) As Boolean

Creates a new directory specified by dirPath.

Returns True for success, False for failure.

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DirDelete
Function DirDelete(ByVal dirPath As String) As Boolean

Deletes the directory specified by dirPath.

Returns True for success, False for failure.

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DirEnsureExists
Function DirEnsureExists(ByVal dirPath As String) As Boolean

Creates all directories necessary such that the entire dirPath exists.

Returns True for success, False for failure.

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FileClose
Sub FileClose()

Closes the currently open file.

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FileContentsEqual
Function FileContentsEqual(ByVal filePath1 As String, ByVal filePath2 As String) As Boolean

Compares the contents of two files and returns True if they are equal and otherwise returns False. The actual contents of the files are only compared if the sizes are equal. The files are not entirely loaded into memory. Instead, they are compared chunk by chunk. This allows for any size files to be compared, regardless of the memory capacity of the computer.

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FileCopy
Function FileCopy(ByVal existingFilepath As String, ByVal newFilepath As String, ByVal failIfExists As Boolean) As Boolean

Copys existingFilepath to newFilepath. If failIfExists is True and newFilepath already exists, then an error is returned.

Returns True for success, False for failure.

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FileDelete
Function FileDelete(ByVal filePath As String) As Boolean

Deletes the file specified by filePath.

Returns True for success, False for failure.

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FileExists
Function FileExists(ByVal filePath As String) As Boolean

Returns True if filePath exists, otherwise returns False.

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FileExists3
Function FileExists3(ByVal path As String) As Integer
Introduced in version 9.5.0.45

Returns 1 if the file exists, 0 if the file does not exist, and -1 if unable to check because of directory permissions or some other error that prevents the ability to obtain the information.

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FileOpen
Function FileOpen(ByVal filePath As String, ByVal accessMode As UInteger, ByVal shareMode As UInteger, ByVal createDisposition As UInteger, ByVal attributes As UInteger) As Boolean

This method should only be called on Windows operating systems. It's arguments are similar to the Windows Platform SDK function named CreateFile. For Linux, MAC OS X, and other operating system, use the OpenForRead, OpenForWrite, OpenForReadWrite, and OpenForAppend methods.

Opens a file for reading or writing. The arguments mirror the Windows CreateFile function:

Access Modes:
GENERIC_READ	(0x80000000)
GENERIC_WRITE (0x40000000)

Share Modes:
FILE_SHARE_READ(0x00000001)
FILE_SHARE_WRITE(0x00000002)

Create Dispositions
CREATE_NEW          1
CREATE_ALWAYS       2
OPEN_EXISTING       3
OPEN_ALWAYS         4
TRUNCATE_EXISTING   5

// Attributes:
FILE_ATTRIBUTE_READONLY         0x00000001
FILE_ATTRIBUTE_HIDDEN           0x00000002
FILE_ATTRIBUTE_SYSTEM           0x00000004
FILE_ATTRIBUTE_DIRECTORY        0x00000010
FILE_ATTRIBUTE_ARCHIVE          0x00000020
FILE_ATTRIBUTE_NORMAL           0x00000080
FILE_ATTRIBUTE_TEMPORARY	   0x00000100

Returns True for success, False for failure.

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FileRead
Function FileRead(ByVal maxNumBytes As Integer) As Byte()

Reads bytes from the currently open file. maxNumBytes specifies the maximum number of bytes to read. Returns an empty byte array on error.

Returns an empty byte array on failure

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FileReadBd
Function FileReadBd(ByVal maxNumBytes As Integer, ByVal binData As BinData) As Boolean
Introduced in version 9.5.0.64

Reads bytes from the currently open file. maxNumBytes specifies the maximum number of bytes to read. Appends the bytes to the binData.

Returns True for success, False for failure.

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FileRename
Function FileRename(ByVal existingFilepath As String, ByVal newFilepath As String) As Boolean

Renames a file from existingFilepath to newFilepath.

Returns True for success, False for failure.

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FileSeek
Function FileSeek(ByVal offset As Integer, ByVal origin As Integer) As Boolean

Sets the file pointer for the currently open file. The offset is an offset in bytes from the origin. The origin can be one of the following:

0 = Offset is from beginning of file.
1 = Offset is from current position of file pointer.
2 = Offset is from the end-of-file (offset may be negative).

Returns True for success, False for failure.

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FileSize
Function FileSize(ByVal filePath As String) As Integer

Returns the size, in bytes, of a file. Returns -1 for failure.

Returns True for success, False for failure.

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FileWrite
Function FileWrite(ByVal data As Byte()) As Boolean

Writes bytes to the currently open file.

Returns True for success, False for failure.

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FileWriteBd
Function FileWriteBd(ByVal binData As BinData, ByVal offset As Integer, ByVal numBytes As Integer) As Boolean
Introduced in version 9.5.0.64

Writes the contents of binData to the currently open file. To specify the entire contents of binData, set both offset and numBytes equal to 0. To write all remaining data starting at offset, then set numBytes equal to 0.

Returns True for success, False for failure.

More Information and Examples
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GenBlockId
Function GenBlockId(ByVal index As Integer, ByVal length As Integer, ByVal encoding As String) As String
Introduced in version 9.5.0.58

This is purely a utility/convenience method -- initially created to help with block file uploads to Azure Blob storage. It generates a block ID string that is the decimal representation of the index in length chars, and then encoded according to encoding (which can be an encoding such as "base64", "hex", "ascii", etc.) For example, if index = 8, length = 12, and encoding = "base64", then the string "00000012" is returned base64 encoded.

Returns Nothing on failure

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GetDirectoryName
Function GetDirectoryName(ByVal path As String) As String
Introduced in version 9.5.0.64

Returns the directory information for the specified path string.

GetDirectoryName('C:\MyDir\MySubDir\myfile.ext') returns 'C:\MyDir\MySubDir\'
GetDirectoryName('C:\MyDir\MySubDir') returns 'C:\MyDir\'
GetDirectoryName('C:\MyDir\') returns 'C:\MyDir\'
GetDirectoryName('C:\MyDir') returns 'C:\'
GetDirectoryName('C:\') returns 'C:\'

Returns Nothing on failure

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GetExtension
Function GetExtension(ByVal path As String) As String
Introduced in version 9.5.0.64

Returns the extension of the specified path string.

GetExtension('C:\mydir.old\myfile.ext') returns '.ext'
GetExtension('C:\mydir.old\') returns ''

Returns Nothing on failure

More Information and Examples
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GetFileName
Function GetFileName(ByVal path As String) As String
Introduced in version 9.5.0.64

Returns the file name and extension of the specified path string.

GetFileName('C:\mydir\myfile.ext') returns 'myfile.ext'
GetFileName('C:\mydir\') returns ''

Returns Nothing on failure

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GetFileNameWithoutExtension
Function GetFileNameWithoutExtension(ByVal path As String) As String
Introduced in version 9.5.0.64

Returns the file name of the specified path string without the extension.

GetFileNameWithoutExtension('C:\mydir\myfile.ext') returns 'myfile'
GetFileNameWithoutExtension('C:\mydir\') returns ''

Returns Nothing on failure

More Information and Examples
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GetFileTime
Function GetFileTime(ByVal path As String, ByVal which As Integer) As CkDateTime
Introduced in version 9.5.0.71

Gets one of the following date/times for a file:

0: Last-modified
1: Last-access
2: Creation
The "path" argument indicates which time to return. The values can be 0, 1, or 2.

Note: Linux filesystems do not keep a file's creation date/time. In such a case, this method will return the last-modified time.

Returns Nothing on failure

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GetLastModified
Function GetLastModified(ByVal path As String) As CkDateTime
Introduced in version 9.5.0.66

Gets the last-modified date/time for a file.

Returns Nothing on failure

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GetNumBlocks
Function GetNumBlocks(ByVal blockSize As Integer) As Integer
Introduced in version 9.5.0.58

Returns the number of blocks in the currently open file. The number of bytes per block is specified by blockSize. The number of blocks is the file size divided by the blockSize, plus 1 if the file size is not evenly divisible by blockSize. For example, if the currently open file is 60500 bytes, and if the blockSize is 1000 bytes, then this method returns a count of 61 blocks.

Returns -1 if no file is open. Return 0 if the file is completely empty (0 bytes).

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GetTempFilename
Function GetTempFilename(ByVal dirPath As String, ByVal prefix As String) As String

Creates a temporary filepath of the form dirPath\prefix_xxxx.TMP Where "xxxx" are random alpha-numeric chars. The returned filepath is guaranteed to not already exist.

Returns Nothing on failure

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OpenForAppend
Function OpenForAppend(ByVal filePath As String) As Boolean

Opens a file for appending. If filePath did not already exists, it is created. When an existing file is opened with this method, the contents will not be overwritten and the file pointer is positioned at the end of the file.

If the open/create failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

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OpenForRead
Function OpenForRead(ByVal filePath As String) As Boolean

Opens a file for reading. The file may contain any type of data (binary or text) and it must already exist. If the open failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

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OpenForReadWrite
Function OpenForReadWrite(ByVal filePath As String) As Boolean

Opens a file for reading/writing. If filePath did not already exists, it is created. When an existing file is opened with this method, the contents will not be overwritten, but the file pointer is positioned at the beginning of the file.

If the open/create failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

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OpenForWrite
Function OpenForWrite(ByVal filePath As String) As Boolean

Opens a file for writing. If filePath did not already exists, it is created. When an existing file is opened with this method, the contents will be overwritten. (For example, calling OpenForWrite on an existing file and then immediately closing the file will result in an empty file.) If the open/create failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

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ReadBinaryToEncoded
Function ReadBinaryToEncoded(ByVal filePath As String, ByVal encoding As String) As String

Reads the entire contents of a binary file and returns it as an encoded string (using an encoding such as Base64, Hex, etc.) The encoding may be one of the following strings: base64, hex, qp, or url.

Returns Nothing on failure

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ReadBlock
Function ReadBlock(ByVal blockIndex As Integer, ByVal blockSize As Integer) As Byte()
Introduced in version 9.5.0.58

Reads the Nth block of a file, where the size of each block is specified by blockSize. The first block is at blockIndex 0. If the block to be read is the last in the file and there is not enough data to fill an entire block, then the partial block is returned.

Returns an empty byte array on failure

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ReadEntireFile
Function ReadEntireFile(ByVal filePath As String) As Byte()

Reads the entire contents of a binary file and returns the data.

Returns an empty byte array on failure

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ReadEntireTextFile
Function ReadEntireTextFile(ByVal filePath As String, ByVal charset As String) As String

Reads the entire contents of a text file, interprets the bytes according to the character encoding specified by charset, and returns the text file as a string.

Returns Nothing on failure

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ReassembleFile
Function ReassembleFile(ByVal partsDirPath As String, ByVal partPrefix As String, ByVal partExtension As String, ByVal reassembledFilename As String) As Boolean

Reassembles a file previously split by the SplitFile method.

Returns True for success, False for failure.

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ReplaceStrings
Function ReplaceStrings(ByVal filePath As String, ByVal charset As String, ByVal existingString As String, ByVal replacementString As String) As Integer

Replaces all occurrences of existingString with replacementString in a file. The character encoding, such as utf-8, ansi, etc. is specified by charset.

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SaveLastError
Function SaveLastError(ByVal path As String) As Boolean

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns True for success, False for failure.

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SetCurrentDir
Function SetCurrentDir(ByVal dirPath As String) As Boolean

Sets the current working directory for the calling process to dirPath.

Returns True for success, False for failure.

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SetFileTimes
Function SetFileTimes(ByVal filePath As String, ByVal createTime As CkDateTime, ByVal lastAccessTime As CkDateTime, ByVal lastModTime As CkDateTime) As Boolean

Sets the create date/time, the last-access date/time, and the last-modified date/time for a file. For non-Windows filesystems where create times are not implemented, the createTime is ignored.

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SetLastModified
Function SetLastModified(ByVal filePath As String, ByVal lastModified As CkDateTime) As Boolean

Sets the last-modified date/time for a file.

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SplitFile
Function SplitFile(ByVal fileToSplit As String, ByVal partPrefix As String, ByVal partExtension As String, ByVal partSize As Integer, ByVal destDir As String) As Boolean

Splits a file into chunks. Please refer to the example below:

Returns True for success, False for failure.

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TreeDelete
Function TreeDelete(ByVal path As String) As Boolean

Deletes an entire directory tree (all files and sub-directories).

Returns True for success, False for failure.

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WriteEntireFile
Function WriteEntireFile(ByVal filePath As String, ByVal fileData As Byte()) As Boolean

Opens/creates filePath, writes fileData, and closes the file.

Returns True for success, False for failure.

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WriteEntireTextFile
Function WriteEntireTextFile(ByVal filePath As String, ByVal textData As String, ByVal charset As String, ByVal includedPreamble As Boolean) As Boolean

Opens filePath, writes textData using the character encoding specified by charset, and closes the file. If includedPreamble is True and the charset is Unicode or utf-8, then the BOM is included at the beginning of the file.

Returns True for success, False for failure.

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