1. In the folder src/bin, create a file called string.rs.
2. Add the following code, and run it with cargo run --bin string:

1   fn main() {
2     // As a String is a kind of vector,
3     // you can construct them the same way
4     let mut s = String::new();
5     s.push('H'),
6     s.push('i'),
7     println!("s: {}", s);
8
9     // The String however can also be constructed
10    // from a string slice (&str)
11    // The next two ways of doing to are equivalent
12    let s = "Hello".to_string();
13    println!("s: {}", s);
14    let s = String::from("Hello");
15    println!("s: {}", s);
16
17    // A String in Rust will always be valid UTF-8
18    let s = " Þjóðhildur  ".to_string();
19    println!("s: {}", s);
20
21    // Append strings to each other
22    let mut s = "Hello ".to_string();
23    s.push_str("World");
24
25    // Iterate over the character
26    // A "character" is defined here as a
27    // Unicode Scalar Value
28    for ch in "Tubular".chars() {
29        print!("{}.", ch);
30    }
31    println!();
32    // Be careful though, a "character" might not
33    // always be what you expect
34    for ch in "y̆".chars() {
35        // This does NOT print y̆
36        print!("{} ", ch);
37    }
38    println!();

Use the following code to split a string in various ways:

42    // Split a string slice into two halves
43    let (first, second) = "HelloThere".split_at(5);
44    println!("first: {}, second: {}", first, second);
45
46    // Split on individual lines
47    let haiku = "
48                 she watches

49                 satisfied after love

50                 he lies

51                 looking up at nothing

52                 ";
53    for line in haiku.lines() {
54        println!("	{}.", line);
55    }
56
57    // Split on substrings
58    for s in "Never;Give;Up".split(';') {
59        println!("{}", s);
60    }
61    // When the splitted string is at the beginning or end,
62    // it will result in the empty string
63    let s: Vec<_> = "::Hi::There::".split("::").collect();
64    println!("{:?}", s);
65
66    // If you can eliminate the empty strings at the end
67    // by using split_termitor
68    let s: Vec<_> = "Mr. T.".split_terminator('.').collect();
69    println!("{:?}", s);
70
71    // char has a few method's that you can use to split on
72    for s in "I'm2fast4you".split(char::is_numeric) {
73        println!("{}", s);
74    }
75
76    // Split only a certain amount of times
77    for s in "It's not your fault, it's mine".splitn(3,
        char::is_whitespace) {
78        println!("{}", s);
79    }
80
81    // Get only the substrings that match a pattern
82    // This is the opposite of splitting
83    for c in "The Dark Knight rises".matches(char::is_uppercase) {
84        println!("{}", c);
85    }
86
87    // Check if a string starts with something
88    let saying = "The early bird gets the worm";
89    let starts_with_the = saying.starts_with("The");
90    println!(
        "Does "{}" start with "The"?: {}",
         saying,
         starts_with_the
      );
91    let starts_with_bird = saying.starts_with("bird");
92    println!(
        "Does "{}" start with "bird"?: {}",
         saying,
         starts_with_bird
      );
93
94    // Check if a string ends with something
95    let ends_with_worm = saying.ends_with("worm");
96    println!("Does "{}" end with "worm"?: {}", saying,
        ends_with_worm);

97
98    // Check if the string contains something somewhere
99    let contains_bird = saying.contains("bird");
100   println!("Does "{}" contain "bird"?: {}", saying,
        contains_bird);

Remove whitespace:

105   // Splitting on whitespace might not result in what you expect
106   let a_lot_of_whitespace = "    I   love spaaace     ";
107   let s: Vec<_> = a_lot_of_whitespace.split(' ').collect();
108   println!("{:?}", s);
109   // Use split_whitespace instead
110   let s: Vec<_> = 
        a_lot_of_whitespace.split_whitespace().collect();
111   println!("{:?}", s);
112
113   // Remove leading and trailing whitespace
114   let username = "   P3ngu1n
".trim();
115   println!("{}", username);
116   // Remove only leading whitespace
117   let username = "   P3ngu1n
".trim_left();
118   println!("{}", username);
119   // Remove only trailing whitespace
120   let username = "   P3ngu1n
".trim_right();
121   println!("{}", username);
122
123
124   // Parse a string into another data type
125   // This requires type annotation
126   let num = "12".parse::<i32>();
127   if let Ok(num) = num {
128     println!("{} * {} = {}", num, num, num * num);
129   }

Modify the string:

133   // Replace all occurences of a pattern
134   let s = "My dad is the best dad";
135   let new_s = s.replace("dad", "mom");
136   println!("new_s: {}", new_s);
137
138   // Replace all characters with their lowercase
139   let lowercase = s.to_lowercase();
140   println!("lowercase: {}", lowercase);
141
142   // Replace all characters with their uppercase
143   let uppercase = s.to_uppercase();
144   println!("uppercase: {}", uppercase);
145
146   // These also work with other languages
147   let greek = "ὈΔΥΣΣΕΎΣ";
148   println!("lowercase greek: {}", greek.to_lowercase());
149
150   // Repeat a string
151   let hello = "Hello! ";
152   println!("Three times hello: {}", hello.repeat(3));
153 }