[Rookie] Char vs String

Hey,

this is a beginner question! So please be kind 😉

I created a SAP PI a message interface that includes string fields as data types with a

minlength and a maxlength.

After creating an ABAP Proxy I can use this interface in my ABAP program. Without

the minlength and maxlength attributes, he just created strings in ABAP proxy. With

these attributes he create a char type.

I'm not familiar with chars so how to fill these:

a) hard coded in source code

b) with a dynpro (using parameter command)

I tried to fill these fields like a normal string:

it-SEARCH_FOR-AUTHOR_LAST_NAME = "Smith".

But it doesn't work. So how to handle these chars in ABAP?

thx

chris