(二) Swift [Basic Operators]

An operator is a special symbol or phrase that you use to check, change, or combine values.

• Unary Operators

var age = -3
var flag = false
flag = !flag

• Binary Operators

let sum = 1 + 2
let multi = 2 * 3

• Ternary Operators

let a = false
let value = a ? 1 : 2 // value is 2

• Assignment Operator [The assignment operator (=) doesn’t return a value]

var age = 3
let value = 10
if age = value { //error
    // This is not valid, because age =  value does not return a value.
}

• Arithmetic Operators
  Swift supports the four standard arithmetic operators for all number types:

1. Addition (+)
2. Subtraction (-)
3. Multiplication (*)
4. Division (/)

The addition operator is also supported for String concatenation:

var message = "hello "
message += "andy."

Unlike the arithmetic operators in C and Objective-C, the Swift arithmetic operators don’t allow values to overflow by default. You can opt in to value overflow behavior by using Swift’s overflow operators (such as a &+ b).

• Remainder Operator

let a = 7 % 3 // 1
let b = -7 % 3 // -1
let c = -3 % 7 // -3

• Unary Minus & Unary Plus Operator

var value = 3
let res = -value // -3
var len = -5
value = +len // -5

• Compound Assignment Operators

var value = 1
value += 2 // 3
value -= 1 // 2
value *= 2 // 4

• Comparison Operators

Equal to (a == b)
Not equal to (a != b)
Greater than (a > b)
Less than (a < b)
Greater than or equal to (a >= b)
Less than or equal to (a <= b)

• Range Operators
  1.The closed range operator (a...b)
  2.The half-open range operator (a..

• Logical Operators [The Boolean logic values just only 'true' and 'false']
  Logical NOT (!a)
  Logical AND (a && b)
  Logical OR (a || b)