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Strings are first-class in Perl. The language was designed for them.

Concatenation with .:

my $s = "hello" . " " . "world";    # "hello world"
$s .= "!";                            # append in-place

Repetition with x:

my $line = "-" x 30;     # 30 dashes
my @row = (0) x 5;        # (0, 0, 0, 0, 0)

Length with length:

length "hello"   # 5

Case:

uc "hi"          # "HI"
lc "HI"          # "hi"
ucfirst "hello"  # "Hello"
lcfirst "HELLO"  # "hELLO"

Substring — substr is read OR write:

my $s = "hello world";
print substr($s, 0, 5);        # "hello"
print substr($s, 6);            # "world"  (to end)
print substr($s, -5);           # "world"  (negative offset)

substr($s, 0, 5) = "howdy";    # in-place replace

Index search:

index("hello world", "world")   # 6
index("hello world", "xyz")     # -1 (not found)
rindex("hello hello", "hello")   # 6 (last occurrence)

sprintf — formatted string (like printf to a string):

my $msg = sprintf("%s scored %d (%.1f%%)", "Ada", 95, 95.0);
# "Ada scored 95 (95.0%)"

Format specifiers: %d integer, %f float, %s string, %x hex, %-10s left-pad, %5d right-pad, %.2f 2 decimals.

split and join:

my @parts = split /,/, "a,b,c,d";   # ("a", "b", "c", "d")
my $back = join ",", @parts;          # "a,b,c,d"

split /\s+/, $line;                    # split on whitespace
split //,    "hello";                  # ('h','e','l','l','o') — empty pattern

tr/// — transliteration (NOT regex). Translate or count characters:

my $s = "hello";
(my $upper = $s) =~ tr/a-z/A-Z/;       # "HELLO"
my $vowels = ($s =~ tr/aeiou//);       # 2 (count vowels)

reverse — works on strings AND lists:

reverse "hello";                       # in scalar context: "olleh"
reverse(1, 2, 3);                      # (3, 2, 1)

chomp vs chop:

• chomp $s — remove trailing \n (or whatever $/ is)
• chop $s — remove last character regardless

Comparison: eq, lt, cmp (NEVER == or < for strings):

"apple" eq "apple"   # true
"apple" lt "banana"   # true (alphabetical)
"apple" cmp "banana" # -1