How can I get the number of times a substring appears in a text

Question

I want to get the number of occurrences of a substring in a text.

fullText = 'aa_bb_cc_dd_eeeee_ff'
substr   = 'ee'

I want to count how many times ee matches aa_bb_cc_dd_eeeee_ff, and the result should be 4.

Answer 1

@sawa's solution is more efficient (and general) but if you want to do it without regexes, here's another way:

'aa_bb_cc_dd_eeeee_ff'.chars.each_cons(2).inject(0) { |c, (i,j)| 
    c+=1 if (i == 'e' && i == j); c 
 }

Answer 2

'aa_bb_cc_dd_eeeee_ff'.scan(/(?=ee)/).length
# => 4