Generate numeric code based on string value

In my cell array, I have one column which contains string values such as a_abc_ABC. How can I generate a new column/ variable which assigns a number to each a_abc_ABC combination? E.g., a_abc_ABC could be 1, a_def_ABC could be 2 etc.

Answer 1

[Thorsten]

c = {'a_abc_ABC', 'a_def_ABC', 'b_def_ABC', 'a_abc_ABC', 'a_def_ABC'};
[~, ~, c_num] = unique(c);