[Tutor] count words

[reavey]

Sirs:
I'd like to count the number of times  a letter occurs  in a string.
I've been looking at c. It seems that this type of problem is being
assigned in cs classes on graduate and advanced undergraduate classes in
the US.
Yet, I'm unable to find a library function or simply code written as a
model to help me.
Any pointer in the direction would be greatly appreciated.
I would like to expand this model to include Dolce words, to help
children with reading difficulties.
TIA
Re-v