pTAL Conversion Guide

TAL Standard Routines

pTAL Conversion Guide—527302-002

17-8

$LEN

$LEN is a TAL routine for which pTAL has a built-in routine with the same name but

slightly different behavior.

$LEN returns the length, in bytes, of a variable.

identifier

is the identifier of a simple variable, array element, pointer, structure, or structure

data item.

TAL

The TAL compiler adds a filler byte at the end of some structures to round the length of

the structure up to an even number of bytes. In some cases, however, the TAL

compiler does not include the filler byte when it calculates the value it returns to the

caller of $LEN.

TAL does not return an error for the following cases:

•

$LEN function applied to a structure whose last item is an UNSIGNED field

•

$LEN applied to a referral substructure problem.

pTAL

The native compiler reports an error if you apply the $LEN routine to a structure that

consists of an odd number of bytes, exclusive of a pad byte. You can avoid this error

by using one of the following solutions:

•

Declare explicitly a one-byte filler item at the end of structures that consist of an

odd number of bytes.

•

Use $BITLENGTH instead of $LEN.

The native compiler reports an error if you apply $LEN to an UNSIGNED variable or

structure field. Use $BITLENGTH to obtain the length of an UNSIGNED variable or

structure.

variable( )

VST096.vsd

$LEN