38 — Name list: reading a file line by line

Guide 37 saved one piece of text. When there are several names, it is easier to keep one per line and turn them back into a list on the way in.

A program that uses files does not run on the site. Try this on your own computer.

#Steps

1. Join the list into one piece of text. A newline between them puts one on each line:

   set friends to list of Mina, Ada, Grace
   set text to friends joined by newline
   show text
   

   copyrun it →

2. Save that text to a file:

   set friends to list of Mina, Ada, Grace
   set text to friends joined by newline
   write text to "names.txt"
   

   copyrun it →

3. Read it back and turn it into a list again. split by line does that:

   read "names.txt" into memo
   set names to memo split by line
   show how many names
   

   copyrun it →

4. You can walk it knowing which one you are on:

   set names to list of Mina, Ada
   for each name in names with place
       show place
       show name
   end
   

   copyrun it →

   place counts from 1.

5. All of it:

   set friends to list of Mina, Ada, Grace
   set text to friends joined by newline
   write text to "names.txt"
   read "names.txt" into memo
   set names to memo split by line
   show how many names
   for each name in names with place
       show place
       show name
   end
   

   copyrun it →

   joined and split are opposites. A list becomes text and the text becomes a list again, with a file in between.

#Try it yourself

Ask for names, put each in a list, and save the file when you are done. Next time, read that file first and add to it, so the list grows.

#What you learned

• <list> joined by newline makes text with one item per line.
• <text> split by line turns it back into a list.
• A file between the two makes the list outlive the program.
• with place gives you which one you are on, counting from 1.