Binary files

Opening binary files

The syntax is:

Open fileName For Binary As fileNumber

Record-length arguments are ignored.

If the file does not exist, it is created, regardless of the access type supplied to the Open statement.

Using variable-length fields

Binary files can hold variable-length records. Since you need to know the string sizes to read them, you should assign a length field to each variable-length record (each string). This is not necessary if the string is a component of a user-defined type; in this case, LotusScript® automatically assigns one.

Binary access provides a byte-by-byte view of a file. A file appears to be a continuous stream of bytes, which may or may not be alphanumeric characters.

Writing to binary files

To write to a binary file, use this Put statement:

Put fileNumber , bytePosition , variableName

Here, the bytePosition parameter is the position in the file at which to start writing. The first byte in a file is at position 1; position zero is illegal, and results in an error.

Reading from binary files

To read data from a binary file, use the following:

• Get

  The Get statement reads the correct number of bytes into any variable of known length, such as a fixed-length string or an integer. For variable-length strings, the number of characters read equals the current length of the string. This will be zero for uninitialized variable-length strings so you should first set the current length to the length of the string to be read. If the string in the file is within a user-defined type, the string length was stored by LotusScript® with the string.

• Seek

  The Seek statement sets the byte position in an open file. The syntax is:

  Seek [#] fileNumber, position

  where fileNumber is the number assigned to the file when it was opened and position is the desired file position for the next read operation. In a binary file, this is a non-zero byte location. The record number in a Get statement or Put statement overrides a file position set by a Seek statement.

• Input

  The Input function or the Input$ function also reads data from a binary file. The syntax is:

  dataHold = Input ( numBytes , fileNumber )

  where dataHold is a Variant. (If the Input$ function were used instead of the Input function, dataHold is a String.) This function reads numBytes bytes from the file and returns them in the variable dataHold.