Counting regex pattern matches in one line using sed or grep?

Question

I want to count the number of matches there is on one single line (or all lines as there always will be only one line).

I want to count not just one match per line as in

Answer 1

You could use grep -o then pipe through wc -l:

$ echo "123 123 123" | grep -o 123 | wc -l
3