Branches

Branching in the three languages.

C++

Rust

Java


const int var = 3;

  if(var < 0) {
      cout << "Var is < 0" << endl;
  } else if(var == 0) {
      cout << "Var is 0" << endl;
  } else {
      cout << "Var is > 0" << endl;
  }

  switch(var) {
  case 1:
      cout << "Var is 1" << endl;
      break;
  case 2:
      cout << "Var is 2" << endl;
      break;
  default:
      cout << "Var is unknown" << endl;
  }




let var = 3;

if var < 0 {
    println!("Var is < 0");
} else if var == 0 {
    println!("Var is 0");
} else {
    println!("Var is > 0");
}

let gt_0 = if var > 0 { true } else { false };

match var {
    1 => println!("Var is 1"),
    2 => println!("Var is 2"),
    3 => println!("Var is 3"),
    _ => println!("Var is unknown"),
}




final int var = 3;

    if(var < 0) {
        System.out.println("Var is < 0");
    } else if(var == 0) {
        System.out.println("Var is 0");
    } else {
        System.out.println("Var is > 0");
    }

    switch(var) {
    case 1:
        System.out.println("Var is 1");
        break;
    case 2:
        System.out.println("Var is 2");
        break;
    case 3:
        System.out.println("Var is 3");
        break;
    default:
        System.out.println("Var is unknown");
    }


Basic if-then-else branches in all three languages are essentially the same. Where C++ and Java do not require { } if there is only a single expression after the condition, Rust always requires a code block.

Rust introduces pattern matching with the match keyword. It can be used much like switch in C++ or Java as shown.

Rust also introduces if let expressions that allow you to set a variable based upon a condition being true or false.