Programming Discussion Thread

[shuffle2]

(11-11-2012, 06:25 AM)AnyOldName3 Wrote: Now, back vaguely towards actual programming:

Can someone who knows some java help me with something. For a program I'm working on I need a method which puts the frequency of each character in the alphabet as a separate entry into an array (or as parts of the internet have suggested when I googled it, a hashmap, which I don't have a clue how to use). The program overall will put this data into a .csv file with a user specified name (which I've already got working). Basically, I have no idea what functions will help me, so can't even write a psuedocode version. When I looked it up, I found some examples, but don't like using other people's code unless I know what each line does and why, which is why I'm asking for help: I'd like to be told generally what I'll need to do, and which functions I'll need, and why, then try and make it myself from that information.

in high level languages, hashmaps typically work such that you have pairs of values, called a "key", and a "value". The key is used as if it is an index into the hashmap.

Consider a normal array where you might do something like this:

Code:

alphabet[0] == "a"

hashmaps make it easy to use whatever datatype you want as the index, so instead of using integers you can use strings, for example:

Code:

alphabet_indices["a"] == 0

you can use this to easily do something like:

Code:

for character in input_string:
    hitcounts[character] = hitcounts[character] + 1

...and that's about it.

note i'm not using java, but you should get the idea.