accessing and writing for loop for struct array

ı have created a struct array with 3 level student.name student.score student.letter

ı have the information of the name and the scores of the students but ı have to write a for loop to assıgn letter grades (a-f) to as a third field. Howver, ı cannot reach into the struct of the array, what can I do?

Answer 1

[KSSV]

 Let there be 5 students with the below grades. 

grades = {'a' 'c' 'e' 'f' 'b'} ;
  for i = 1:length(student)
  student(i) = grades{i} ;
  end