lang • read

READ

Variable = READ [ # Stream ] AS Datatype Variable = READ [ # Stream , ] Length

Reading a specific datatype

The first syntax reads the stream Stream as binary data whose type is specified by the Datatype argument. The binary representation is the one used by the WRITE instruction.

If the stream is not specified, then the standard input is used.

The returned datatype can be one of the following: NULL, Boolean, Byte, Short, Integer, Long, Pointer, Single, Float, Date, String, Variant, any Array, Collection or structure.

When reading a string, the length of the string must precede the string contents in the stream data, as specified in Binary Data Representation.

If the stream contents cannot be interpreted, an error is raised.

This instruction uses the byte order of the stream to read the data.

Reading the contents of a string

The second syntax reads from the stream Stream a number of bytes specified by the Length argument, and returns it as a string.

If Length is negative, then at most (- Length) bytes are read until the end of the stream.

If the stream is not specified, then the standard input is used.

Compatibility with Gambas 2

WRITE #Stream, Expression writes the binary form of Expression in Gambas 2.0. In Gambas 3.0 it writes Expression as a string.

So you HAVE to check all your WRITE instructions when converting a Gambas project from 2.0 to 3.0, and specified AS Datatype when need.

By default, the compiler supports the old READ syntax, and the old WRITE syntax as it is compatible.

If you want to detect where you should rewrite your READ / WRITE syntax, you can compile your project by hand with the "--no-old-read-write-syntax" flag. Then the Length argument of WRITE becomes mandatory if the second syntax is used.

Using a Pointer as a stream is not possible anymore. Create a memory stream with the MEMORY instruction instead.

See also