Comparison operators

Comparison operators work with boolean and integer values.

• Equality: ==, for booleans and integers

  Both sides of the equality operator may be optional, even of different levels, so it is for example possible to compare a non-optional with a double-optional (??).

    1 == 1  // is `true`
  
    1 == 2  // is `false`

    true == true  // is `true`
  
    true == false  // is `false`

    let x: Int? = 1
    x == nil  // is `false`

    let x: Int = 1
    x == nil  // is `false`

    // Comparisons of different levels of optionals are possible.
    let x: Int? = 2
    let y: Int?? = nil
    x == y  // is `false`

    // Comparisons of different levels of optionals are possible.
    let x: Int? = 2
    let y: Int?? = 2
    x == y  // is `true`

• Inequality: !=, for booleans and integers (possibly optional)

  Both sides of the inequality operator may be optional, even of different levels, so it is for example possible to compare a non-optional with a double-optional (??).

    1 != 1  // is `false`
  
    1 != 2  // is `true`

    true != true  // is `false`
  
    true != false  // is `true`

    let x: Int? = 1
    x != nil  // is `true`

    let x: Int = 1
    x != nil  // is `true`

    // Comparisons of different levels of optionals are possible.
    let x: Int? = 2
    let y: Int?? = nil
    x != y  // is `true`

    // Comparisons of different levels of optionals are possible.
    let x: Int? = 2
    let y: Int?? = 2
    x != y  // is `false`

• Less than: <, for integers

    1 < 1  // is `false`
  
    1 < 2  // is `true`
  
    2 < 1  // is `false`

• Less or equal than: <=, for integers

    1 <= 1  // is `true`
  
    1 <= 2  // is `true`
  
    2 <= 1  // is `false`

• Greater than: >, for integers

    1 > 1  // is `false`
  
    1 > 2  // is `false`
  
    2 > 1  // is `true`

• Greater or equal than: >=, for integers

    1 >= 1  // is `true`
  
    1 >= 2  // is `false`
  
    2 >= 1  // is `true`