Case and Trim

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Strings are immutable: .upper() and .lower() return a transformed copy — the original string does not change. This makes normalization patterns safe: for example, lowercasing everything before a comparison:

.upper / .lower for case conversion; .trim / .trim_start / .trim_end to strip whitespace.

05-case-and-trim.zolo

Playground

// Feature: Case conversion and whitespace trimming

// Syntax: `s.upper()`, `s.lower()`, `s.trim()`, `s.trim_start()`, `s.trim_end()`

// When to use: normalize input, case-insensitive comparisons, clean input.


// -- upper / lower ---------------------------------------------

print("zolo".upper())
// expected: ZOLO

print("ZOLO".lower())

// expected: zolo


// Strings are immutable — methods return a transformed copy.

let s = "MiXed"
let u = s.upper()
print(u)  // MIXED

print(s)  // MiXed (original untouched)


// Case-insensitive comparison.

let input = "ADMIN"
let role = "admin"
print(input.lower() == role.lower())

// expected: true


// -- trim — removes whitespace from both ends ------------------

let pad = "  hello  "
print("'{pad.trim()}'")

// expected: 'hello'


// Only one side:

print("'{pad.trim_start()}'")  // 'hello  '

print("'{pad.trim_end()}'")  // '  hello'


// Useful for cleaning user input.

let raw = "   alice@email.com   "
let email = raw.trim().lower()
print(email)
// expected: alice@email.com

Challenge

Take an input with extra spaces and mixed case, such as " ZoLo LaNG ". Use .trim() and .lower() chained together to normalize it to "zolo lang".