Strings

Strings are text in double quotes. A single character in single quotes is a Char:

name = "Ada"
greeting = "Hello, " * name * "!"
println(greeting)
println("$name has $(length(name)) letters")
println("2 + 3 = $(2 + 3)")
println(repeat("ab", 3), " ", "ab"^3)
println(typeof('A'), " ", 'A' + 1, " ", Int('A'))

Hello, Ada!
Ada has 3 letters
2 + 3 = 5
ababab ababab
Char B 65

• * concatenates strings (Julia's reasoning: concatenation isn't commutative, like multiplication of matrices).
• $name interpolates a variable; $(expression) interpolates any expression.
• ^ repeats a string.

Indexing

Strings are indexed from 1, and end means the last index:

s = "Julia"
println(s[1], " ", s[end], " ", s[2:4])
println(first(s, 2), " ", last(s, 3))
println(length(s))
for c in s
    print(c, "-")
end
println()

J a uli
Ju lia
5
J-u-l-i-a-

s[1] is a Char; s[2:4] (a range of indices) is a String.

Unicode

Julia strings are UTF-8. Indexes are byte positions, so for text with non-ASCII characters, prefer first, last, iteration, or collect(s) over raw indexes:

word = "naïve"
println(length(word), " characters, ", sizeof(word), " bytes")
println(collect(word))
println(first(word, 3))

5 characters, 6 bytes
['n', 'a', 'ï', 'v', 'e']
naï

Special strings

println("Tab:\tNew line:\nQuote: \" Dollar: \$5")
poem = """
    Roses are red,
    Julia is fast.
    """
print(poem)
println(raw"C:\Users\ada")

Tab:	New line:
Quote: " Dollar: $5
Roses are red,
Julia is fast.
C:\Users\ada

• Escape sequences: \n, \t, \", \\, and \$ for a literal dollar sign.
• Triple-quoted strings span lines and remove the common indentation.
• raw"..." strings don't process escapes or interpolation.

Practice

Given first_name = "grace" and last_name = "hopper", print Hopper, Grace (11 letters). Hint: uppercasefirst.

first_name = "grace"
last_name = "hopper"
full = uppercasefirst(last_name) * ", " * uppercasefirst(first_name)
println("$full ($(length(first_name) + length(last_name)) letters)")

Hopper, Grace (11 letters)