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String Manipulation

Rust provides a rich set of methods for manipulating strings. These methods allow you to search, transform, split, and clean string data efficiently.

Common String Methods

Trimming Whitespace

The .trim() method removes leading and trailing whitespace from a string:

rust
let messy = "  hello world  ";
assert_eq!(messy.trim(), "hello world");

You can also trim only from one side with .trim_start() and .trim_end().

Case Conversion

Convert strings to lowercase or uppercase:

rust
let mixed = "Hello World";
assert_eq!(mixed.to_lowercase(), "hello world");
assert_eq!(mixed.to_uppercase(), "HELLO WORLD");

Searching

Check if a string contains a substring:

rust
let text = "Rust is awesome";
assert!(text.contains("awesome"));
assert!(!text.contains("boring"));

Replacing

Replace occurrences of a pattern with another string:

rust
let original = "hello world";
assert_eq!(original.replace("world", "Rust"), "hello Rust");

Splitting

Split a string into parts based on a delimiter:

rust
let csv = "apple,banana,cherry";
let fruits: Vec<&str> = csv.split(',').collect();
assert_eq!(fruits, vec!["apple", "banana", "cherry"]);

Your Task

Implement the following functions:

  1. clean_string(s: &str) -> String - Remove leading and trailing whitespace, then convert to lowercase
  2. contains_word(text: &str, word: &str) -> bool - Check if the text contains the given word (case-insensitive)
  3. replace_word(text: &str, from: &str, to: &str) -> String - Replace all occurrences of from with to
  4. split_and_trim(s: &str, delimiter: char) -> Vec<String> - Split the string by the delimiter and trim each part
  5. normalize_whitespace(s: &str) -> String - Replace all sequences of whitespace with a single space, and trim

Examples
rust
// clean_string: trim and lowercase
assert_eq!(
    clean_string("  Hello World  "),
    "hello world"
);
 
// contains_word: case-insensitive search
assert_eq!(
    contains_word("Rust is awesome", "AWESOME"),
    true
);
assert_eq!(
    contains_word("Rust is awesome", "boring"),
    false
);
 
// replace_word: simple replacement
assert_eq!(
    replace_word("hello world", "world", "Rust"),
    "hello Rust"
);
 
// split_and_trim: split and clean each part
assert_eq!(
    split_and_trim("apple , banana , cherry", ','),
    vec!["apple", "banana", "cherry"]
);
 
// normalize_whitespace: clean up messy whitespace
assert_eq!(
    normalize_whitespace("  hello    world  "),
    "hello world"
);

Hints
Click here for hints
  • For clean_string, chain .trim() and .to_lowercase()
  • For contains_word, convert both strings to the same case before checking
  • For replace_word, use the .replace() method
  • For split_and_trim, use .split() then .map() with .trim(), and .collect()
  • For normalize_whitespace, use .split_whitespace() to automatically handle multiple spaces, then .collect::<Vec<_>>().join(" ")
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