Help: for loop doesn't work?

[a]

I'm studying the frequency of 5-letter words composed of {a,b,c,d,e} in a
string, I wanna build an array recording the frequencies of (aaaaa, aaaab,
...., caaaa, ..., eeeee). I find that for loop can work well if I hard-code
the number, what can I do if I wanna study n-letter word (e.g. n=3, 100,
3732)?

 

[Thad Smith]

I'm studying the frequency of 5-letter words composed of {a,b,c,d,e} in a
string, I wanna build an array recording the frequencies of (aaaaa, aaaab,
..., caaaa, ..., eeeee). I find that for loop can work well if I hard-code
the number, what can I do if I wanna study n-letter word (e.g. n=3, 100,
3732)?

I suggest, for a given n, making a single pass through the string, building
a data structure containing all the defined words and a count of how many
times each is used. A tree or hash table would work well.

 

[CBFalconer]

I suggest, for a given n, making a single pass through the string,
building a data structure containing all the defined words and a
count of how many times each is used. A tree or hash table would
work well.

Take a look at the demonstration application for hashlib, wdfreq.
Modification should do what the OP wants. hashlib is available,
GPL licensed, at:

<http://cbfalconer.home.att.net/download/>