Join

Strings are everywhere in programs. And programs themselves are represented as strings. An array can contain strings—or it can be merged into a single string with delimiters.

Method notes

Join() acts on string arrays (or arrays of any type of element that are converted into strings). We can use join to round-trip our data with split().

An example program

Consider this program. We see a string array that contains three string literals. On the string array instance we call join.

values = ["aa", "bb", "cc"]

# Use the join method to combine a string array.
joined = values.join(";")

# Print the result.
puts joined
aa;bb;cc

No delimiter

We can use join with no delimiter. This converts an array of strings (or 1-char strings which are like characters) into a string.

values = ["a", "b", "c"]

# Join with no delimiter.
# ... This turns an array of characters into a string.
result = values.join

puts result
abc

A review

With split() and join() we can round-trip our data processing. We have a string, and can split it apart. Then we modify elements, and join it together again.