change value of nestef fields (in struct) in loop

Hello

I have some nested structs with many fields

I intend to produce field name and change its value in loop

I use sprintf for creating name of field

and use setfield to change value of field

but because the field name is string (and too long), I could not assing value to it. i use eval in form

for

eval (sprintf('struct name'))= setfield(eval (sprintf('struct name')), 'fieldname', 'intended value' )

end