Big Picture: What's It Doing?

This Go program is like a detective counting letters in a bunch of online documents. It does the following:

1. Downloads Documents: It grabs text files from the website "rfc-editor.org". These files are like technical manuals (RFCs).
2. Counts Letters: It carefully goes through each document, counting how many times each letter of the alphabet appears. It ignores anything that's not a letter and treats uppercase and lowercase the same.
3. Prints Results: Finally, it shows us a nice summary of how often each letter showed up across all the documents it looked at.

Thought Process: How to Cook It Up

Here's how you might think about creating this program:

1. Getting the Ingredients:

   • You'll need Go installed on your computer.
   • We'll use a few built-in Go tools:
     • fmt (for printing things nicely)
     • io (for reading the downloaded text)
     • net/http (for getting files from the web)
     • strings (for working with text)

2. Mixing the Batter:

   • allLetters: We store all the lowercase letters in a string to help us later.
   • countLetters Function:
     • It takes a web address (url) and an empty list (frequency) to store the counts.
     • It downloads the file from the web address.
     • It checks if the download was successful (no errors).
     • It reads all the text from the downloaded file.
     • It loops through each character:
       • Makes the character lowercase.
       • Finds its position in the allLetters string.
       • If it's a letter, increases the count in the frequency list for that letter.

3. Baking the Cake:

   • main Function:
     • Creates a list of 26 zeros to keep track of each letter's count.
     • Loops from 1000 to 1030 to build web addresses for documents numbered 1000 to 1030.
     • Calls countLetters for each address, updating the frequency list.
     • Finally, prints a neat summary: each letter followed by its count.

Example Output

You'll see something like this when you run the program:

a-12345 b-6789 c-101112 ...

This means the letter 'a' appeared 12345 times, 'b' 6789 times, and so on.