diesel expression data field

[luca.rgn]

Good morning.
I'm trying to figure out how diesel expressions work in autocad and I'm doing some tests.
the main problem is with substr.
esempio: file name: xxxxxx-xxxx-xxxx-xxxxxx name layout: Developedthe goal is to replace the characters of the file name from number 18 to 21 with the layout name so I wrote this$(substr,$(getvar,"dwgname"),1,17)$(getvar,"ctab")$(substr,$(getvar,"dwgname"),.this expression is working and fine, but since I want to take only characters from 18 to 21 of the file name does not work.
writing this:$(substr, $(getvar "dwgname"),18,21)It takes all the characters from18th onwards.
Can you explain why?

 

[x11start]

where we work we put as file nameclient-21-570.dwg in which 21 is the year and 570 is the code of the contract. I created in my drawings a data field with the format:

$(substr,$(getvar,dwgname),$(-,$(strlen,$(getvar,dwgname),9),6)

this allows me, starting from the last 9 characters of the file (21-570.dwg) and from them take only 6: i.e. exclude the dwg extension.

the result to video therefore is:

21-570

based on this reasoning, I think you can solve your problem... .

the strlen variable allows me to have a client name of any length.

 

[rpor66]

$(substr,$(getvar,"dwgname"),18,4)
from 18 and 4 characters

 

[Cristallo]

Good morning.
...$(substr, $(getvar "dwgname"),18,21)It takes all the characters from18th onwards.
Can you explain why?

because you tell him to start from the 18th character and take 21
You should tell him $(substr,$(getvar,"dwgname"),18,4)

oops, same answer as rpor