"So I need convert all chars automatically to names of structure which i will use in fieldnames."
Ugh, no, that is the last thing that you need to do. Import your data properly and avoid this situation entirely is what you need to do. Dynamically accessing variables names is how beginners force themselves into writing slow, complex, buggy code. Read this to know why:
It is much more efficient to use indexing, fieldnames, or the columns/rows of a table.
