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  1. // 8.2 Storing UTF-8 Encoded Text with Strings
  2.  
  3. // "strings" in Rust means String and &str for Owned and Borrowed form respectively.
  4. // They both are UTF-8 encoded
  5.  
  6. fn main() {
  7.     // Create a new string
  8.     {
  9.         let mut s = String::new(); // create empty string, to load data into it later
  10.  
  11.         let data = "initial contents";
  12.         let s = data.to_string(); // convert from other type that implement Display trait
  13.  
  14.         let s = "initial contents".to_string(); // load directly from string literal
  15.  
  16.         let s = String::from("initial contents"); // use String associate function
  17.  
  18.         let hello = String::from("สวัสดีครับ");
  19.         println!("{}", hello);
  20.     }
  21.    
  22.     // Update a string
  23.     {
  24.         let mut s1 = String::from("foo");
  25.         let s2 = "bar";
  26.         s1.push_str(s2); // push_str take a string slice, in this case complier will coerce s2 into &s2[..]
  27.         println!("{}, {}", s1, s2);
  28.        
  29.         s1.push('!'); // append only one character
  30.         println!("{}", s1);
  31.     }
  32.    
  33.     // Concatenation with + Operator
  34.     {
  35.         let s1 = String::from("Hello, ");
  36.         let s2 = String::from("World!");
  37.         let s3 = s1 + &s2;  // add operator will deref coerce &String into &str -- &s2 into &s2[..]
  38.                             // so s2 still available here, as add operator does'nt take ownership
  39.                             // but s1 is no longer valid after this, as ownership has moved into s3
  40.     }
  41.    
  42.     // Concatenation with format! Macro
  43.     {
  44.         let s1 = String::from("tic");
  45.         let s2 = String::from("tac");
  46.         let s3 = String::from("toe");
  47.         let s = format!("{}-{}-{}", s1, s2, s3);    // format! works the same way as println!
  48.                                                     // it also never take ownership of any of its parameters
  49.     }
  50.    
  51.     // Indexing to Strings
  52.     {
  53.         let s1 = String::from("Hello");
  54.         // let h = s1[0]; <- this statement will get error as indexing on Unicode Char might return unexpedted result
  55.        
  56.         let len1 = String::from("Hello").len(); // this is just 5 bytes
  57.         let len2 = String::from("สวัสดี").len();  // this is 18 bytes
  58.         println!("len1: {}, len2: {}", len1, len2);
  59.        
  60.         let hello = "สวัสดี";
  61.         let s = &hello[0..3]; // this is valid as long as range is in the char boundary
  62.         // let s = &hello[0..2] <- this slice has invalid range for first char boundary
  63.         println!("{}", s);
  64.     }
  65.    
  66.     // Interating over Strings
  67.     {
  68.         // fetching each char out of string
  69.         for c in "สวัสดี".chars() {
  70.             println!("{}", c);
  71.         }
  72.        
  73.         // fetching each raw byte out of string
  74.         for b in "สวัสดี".bytes() {
  75.             println!("{}", b);
  76.         }
  77.     }
  78.    
  79. }
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