@strings

The @strings module provides functions for manipulating and working with strings.

Import

import @strings

Case Conversion

to_upper()

(s string) -> string

Converts a string to uppercase.

import @strings

do main() {
    println(strings.to_upper("hello"))        // "HELLO"
    println(strings.to_upper("Hello World"))  // "HELLO WORLD"
}

Parameters: s - The string.

Returns: string - Uppercase version.

to_lower()

(s string) -> string

Converts a string to lowercase.

import @strings

do main() {
    println(strings.to_lower("HELLO"))        // "hello"
    println(strings.to_lower("Hello World"))  // "hello world"
}

Parameters: s - The string.

Returns: string - Lowercase version.

Query Functions

is_empty()

(s string) -> bool

Checks if a string is empty or contains only whitespace.

println(strings.is_empty(""))       // true
println(strings.is_empty("   "))    // true
println(strings.is_empty("hello"))  // false

Parameters: s - The string to check.

Returns: bool - true if empty or whitespace-only.

contains()

(s string, sub string) -> bool

Checks if a string contains a substring.

import @strings

do main() {
    println(strings.contains("hello world", "world"))  // true
    println(strings.contains("hello world", "foo"))    // false
}

Parameters: s, sub.

Returns: bool - true if found.

starts_with()

(s string, prefix string) -> bool

Checks if a string starts with a prefix.

import @strings

do main() {
    println(strings.starts_with("hello world", "hello"))  // true
    println(strings.starts_with("hello world", "world"))  // false
}

Parameters: s, prefix.

Returns: bool - true if starts with prefix.

ends_with()

(s string, suffix string) -> bool

Checks if a string ends with a suffix.

import @strings

do main() {
    println(strings.ends_with("hello world", "world"))  // true
    println(strings.ends_with("hello world", "hello"))  // false
}

Parameters: s, suffix.

Returns: bool - true if ends with suffix.

index_of()

(s string, sub string) -> int

Returns the index of the first occurrence of a substring, or -1 if not found.

import @strings

do main() {
    println(strings.index_of("hello world", "world"))  // 6
    println(strings.index_of("hello world", "foo"))    // -1
}

Parameters: s, sub.

Returns: int - Index or -1.

count()

(s string, sub string) -> int

Counts non-overlapping occurrences of a substring.

println(strings.count("hello world", "o"))    // 2
println(strings.count("aaa", "aa"))            // 1

Parameters: s, sub.

Returns: int - Number of occurrences.

Transformation Functions

trim()

(s string) -> string

Removes whitespace from both ends of a string.

import @strings

do main() {
    println(strings.trim("  hello  "))    // "hello"
    println(strings.trim("\n\thello\n"))  // "hello"
}

Parameters: s - The string.

Returns: string - Trimmed string.

trim_left() / trim_right()

(s string) -> string

Removes whitespace from the left or right side only.

import @strings

do main() {
    println(strings.trim_left("  hello  "))   // "hello  "
    println(strings.trim_right("  hello  "))  // "  hello"
}

Parameters: s - The string.

Returns: string - Trimmed string.

replace()

(s string, old string, new string) -> string

Replaces all occurrences of a substring with another string.

import @strings

do main() {
    println(strings.replace("hello world", "world", "EZ"))  // "hello EZ"
    println(strings.replace("aaa", "a", "b"))  // "bbb"
}

Parameters: s, old, new.

Returns: string - Modified string.

repeat()

(s string, count int) -> string

Repeats a string n times.

import @strings

do main() {
    println(strings.repeat("ab", 3))  // "ababab"
    println(strings.repeat("-", 10))  // "----------"
}

Parameters: s, count.

Returns: string - Repeated string.

reverse()

(s string) -> string

Reverses a string.

import @strings

do main() {
    println(strings.reverse("hello"))  // "olleh"
    println(strings.reverse("12345"))  // "54321"
}

Parameters: s - The string.

Returns: string - Reversed string.

Conversion Functions

split()

(s string, sep string) -> [string]

Splits a string into an array of substrings.

import @strings

do main() {
    mut parts = strings.split("a,b,c", ",")
    println(parts)  // {"a", "b", "c"}

    mut words = strings.split("hello world", " ")
    println(words)  // {"hello", "world"}
}

Parameters: s, sep.

Returns: [string] - Array of substrings.

join()

(arr [string], sep string) -> string

Joins an array of strings with a separator.

import @strings

do main() {
    mut parts [string] = {"a", "b", "c"}
    println(strings.join(parts, "-"))  // "a-b-c"
    println(strings.join(parts, ""))   // "abc"
}

Parameters: arr, sep.

Returns: string - Joined string.

slice()

(s string, start int, end int) -> string

Extracts a portion of a string by index. Supports negative indices.

println(strings.slice("hello world", 0, 5))   // "hello"
println(strings.slice("hello world", 6))       // "world"
println(strings.slice("hello world", -5))      // "world"

Parameters: s, start, optional end (defaults to string length).

Returns: string - The extracted substring.

Example Program

import @strings

do main() {
    mut input_text = "  Hello, World!  "

    // Clean up input
    mut cleaned = strings.trim(input_text)
    println("Cleaned:", cleaned)

    // Transform
    println("Upper:", strings.to_upper(cleaned))
    println("Lower:", strings.to_lower(cleaned))

    // Search
    if strings.contains(cleaned, "World") {
        println("Contains 'World'!")
    }

    // Split and rejoin
    mut w = strings.split(cleaned, " ")
    println("Words:", w)

    mut kebab = strings.join(w, "-")
    println("Kebab case:", strings.to_lower(kebab))

    // Build a slug
    mut title = "My Blog Post Title"
    mut slug = strings.to_lower(strings.replace(title, " ", "-"))
    println("Slug:", slug)  // "my-blog-post-title"
}