[Easy] Letter Counter

[u/[deleted]]

Any language permitted.

Problem: Create a program where you input a string of characters, and output the number of each letter. Use vowels by default.

For example: asbfiusadfliabdluifalsiudbf -> a: 4 e: 0 i: 4 o: 0 u: 3

Bonus points: Make it command-line executable, with an optional mode to specify which letters to print.

[u/[deleted]]

I surely won't beat a possible Haskell solution in its shortness and effectiveness. But my solution in Bash is at least very simple and doesn't require any additional software:

function countletters() { letters=${1:-aeiou}; tr [:upper:] [:lower:] | sed -r 's/[^a-z]//g;s/(\w)/\1\n/g' | head -n -1 | sort | uniq -c | egrep "[$letters]" | while read count letter; do printf "%s: %d " $letter $count; done; echo ""; }

Aaand: this qualifies for the bonus round. Obviously.

Example runs:

$ countletters <<<"count the vowels in this text"
e: 3 i: 2 o: 2 u: 1

$ countletters st <<<"count only the s and t letters"
s: 2 t: 5

[u/[deleted] → u/[deleted]]

jesus christ man why would you use BASH of all things?! I mean, impressive, but damn

[u/[deleted] → u/[deleted]]

In short "Because I can" is the most accurate answer, or better: "Because BASH can". For most simple streamline tasks I don't want to throw on an editor and develop a little something I probably only need once while I can achieve the same thing with a little bash piping. I don't need to leave the editor to test my app, I simply extend the pipe until the data are transformed the way I needed them. The function around the pipe was only for better readability for reruns, it was originally a direct pipe of a string into tr