Table of Contents

5.4.5.11 Put Statement

Note

This section describes the implementation of MS-VBAL §5.4.5.11 Put Statement.

Syntax

AST node Instruction kind(s) Notes
KeywordStatementNode Simple Token: Put.

See RD-VBAL §3.4.3 File Statements.

Runtime Semantics

Put writes through the record surface of a file channel, which it shares with Get (RD-VBAL §5.4.5 File Statements). This section describes the record format and record positioning of both statements; see also RD-VBAL §5.4.5.12 Get Statement.

Record Format

Put and Get use MS-VBAL §5.4.5.11's Variant type descriptors and binary widths. The record format is a wire format rather than a behaviour.

The record format follows MS-VBA's, so that a file RD-VBA writes is a file MS-VBA reads.

Data In a record
Boolean Two bytes. True is FF FF.
String, in Random mode Carries a two-byte length prefix.
String, in Binary mode Carries no length prefix.
Variant Preceded by its two-byte type descriptor.
A UDT Each member of the UDT, in declaration order, recursively through a nested UDT (see User-Defined Types).

User-Defined Types

MS-VBAL §5.4.5.11 and MS-VBAL §5.4.5.12 Get Statement say "the value of each member of the UDT is written to the file... in the order in which the members are declared". Put writes, and Get reads, each member of a UDT in declaration order, recursively through a nested UDT.

UDT field declaration order is the order Put writes a record in (RD-VBAL §2.5.2.1.3 User-Defined Type (UDT) Values).

Put #1, , myRecord and Get #1, , myRecord serialize and deserialize a whole UDT in one statement.

Put and Get move the serialized size of a UDT: its fields concatenated, with no padding.

👉 Memory widths of UDT fields are not file widths. See RD-VBAL §2.5.2.1.3 User-Defined Type (UDT) Values for the in-memory side.

UDT field In a record
Variable-length String Its characters.
Fixed-length String ANSI.

Record Positioning

MS-VBAL leaves two gaps in record positioning, and RD-VBA names its choice for each:

Gap RD-VBA's choice
The record length of a Random channel opened without a Len clause The channel counts positions in 128-byte records.
The byte position of record 1 Record number 1 is byte 0 of the file.

Record length. A Random channel whose Open statement declared no Len clause counts positions in 128-byte records. 128 bytes is MS-VBA's own default record length. MS-VBAL §5.4.5.1 Open Statement constrains the Len clause but does not say what an absent Len clause means.

Record 1. MS-VBAL §5.4.5.11 says the file position becomes "exactly <record-number> number of bytes from the start". It also defaults the Put record number to the current file-pointer-position, which MS-VBAL §5.4.5.3 Seek Statement counts from 1.

The record number and the file-pointer-position are one quantity, and Seek and Get must agree on it. That is why record number 1 is byte 0 of the file (RD-VBAL §5.4.5.3 Seek Statement).

Implementation

Name Role
RecordDataFormat Implements the Put/Get record format: MS-VBAL §5.4.5.11's Variant type descriptors and binary widths.
IFileChannel A file channel. Its record surface is the one Put and Get use.

⏮️ RD-VBAL §5.4.5.10 Input Statement | ⏭️ RD-VBAL §5.4.5.12 Get Statement

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