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 WINDEV, WEBDEV AND WINDEV MOBILE
  • Handling errors
  • Position in the file
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WEBDEV
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WINDEV Mobile
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Stored procedures
Reads a block of bytes in an external file.
AndroidAndroid Widget JavaPHP In this version, you can only read a character string from an external file in ANSI format.
Example
WINDEVWEBDEV - Server codeReports and QueriesJavaUser code (UMC)PHPAjax
// Open an external file
FileID = fOpen("C:\MyDirectories\File.txt", foReadWrite)
IF FileID <> -1 THEN
// Read operation in this file
ResRead = fRead(FileID, 200)
...
END
New in version 28
WINDEVWEBDEV - Server codeReports and QueriesJavaUser code (UMC)PHPAjax
// Open an external file
MyFile is DiskFile
MyFile = fOpen("C:\MyDirectories\File.txt", foReadWrite)
IF NOT ErrorOccurred THEN
// Read operation in this file
ResRead = fRead(MyFile, 200)
...
END
Syntax

Reading a block of bytes in an external file Hide the details

<Result> = fRead(<File used> , <Number of bytes to read>)
<Result>: Character string
  • Block of bytes that was read.
  • Empty string ("") if an error occurred. To get more details on the error, use ErrorInfo with the errMessage constant.
<File used>: Integer or DiskFile variable
<Number of bytes to read>: Integer
Number of bytes to read (up to 2 147 483 648 bytes).
If the data is a Unicode string, the number of bytes to read corresponds to:
  • in UTF16: the number of characters multiplied by 2.
  • in UTF32: the number of characters multiplied by 4.
WINDEVWEBDEV - Server codeReports and QueriesiPhone/iPadIOS WidgetMac CatalystUser code (UMC)Ajax

Reading the content of an external file and assigning it to a memory area (identified by its address) Hide the details

<Result> = fRead(<File used> , <Number of bytes to read> , <Address>)
<Result>: Integer
  • Number of bytes read,
  • 0 if an error occurs. To get more details on the error, use ErrorInfo with the errMessage constant.
<File used>: Integer or DiskFile variable
<Number of bytes to read>: Integer
Number of bytes to read (up to 2 147 483 648 bytes).
If the data is a Unicode string, the number of bytes to read corresponds to:
  • in UTF16: the number of characters multiplied by 2.
  • in UTF32: the number of characters multiplied by 4.
<Address>: Address
Address of affected memory section.
Remarks

Handling errors

fRead throws an error in the following cases:
  • the file is not opened,
  • the file is not accessible in read mode,
  • the file is locked by another computer or by another application,
  • therefore, the end of file is reached.

Position in the file

When opening a file, the current position corresponds to:
  • the first file byte (by default),
  • the last byte of the file is the file is opened in "addition" mode (foAdd constant).
This position can be modified by fSeek.
fRead reads the specified elements from the current position. Once fRead has been executed, the current position is set to the last byte read.
Remark: To always read the beginning of the file, you must call fSeek and then fRead.
Business / UI classification: Business Logic
Component: wd280std.dll
See also
Minimum version required
  • Version 9
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