Swift Basics-2

First, the basic operator

let a = 5

var b = ten

b = A

if a = b{

The assignment operator in Swift does not return itself as a value, so compiling is illegal, helping developers avoid mistakes, very human language

}

Second, mathematical operators

let dog:Character = "?? "

let cow:Character = "?? "

let dogcow = dog + Cow

println(dogcow)

//Swift arithmetic operator does not allow overflow, by overflow operator to select the value overflow condition (a& + b)

The // remainder operator can be used for floating-point numbers flost

8 % 2.5 //equals 0.5

//unary minus operator

let three = 3

let minustree =-three

let plusthree =-minustree

println(minustree)

println(plusthree)

//unary plus operator

Three, scope operators

= = =! = = Two identity operator detects whether two object references are from the same object instance

Two ranges

Enclosing (a...b) means: A to B value

For index in 1...5{

println ()

}

Semi-closed

(a). b), Baotou does not pack tail

let names = ["Anna","Alex","BBSC","SDFs"]

Let count = names. Count

for i in 0... count-1{

println("Person \ (i) is called \ (Names[i])")

}

Four, characters and strings

Shortcut keys:

Option +y = "Y"

Emoji = control + commod +space

The string in Swift is not the actual value of the pointer

Initializing an empty string

var emptystring = ""

var anotheremptystr = String ()

If emptystring.isempty{

}

var variablestring = "Horse"

Variablestring + = "and carriage"

Countelements calculating the number of characters in a string

Let countstr = "Hahahh"

println (countstr count is \ (countelements (COUNTSTR)))

The length of the NSString is based on the number of UTF-16 encodings and not on Unicode

The string in swift does not necessarily occupy the same memory space.

string comparison

Let SOMESTR1 = "abc"

Let SOMESTR2 = "abc"

if someStr1 = = somestr2{

}

The string in Swift is not the actual value of the pointer

Prefix equal

Let animals = ["Meat: Tiger", "Carnivorous: Lion", "Grass: Sheep", "Grass: Cattle", "Grass: Horse")

var acount = 0

For animal in animals{

If animal.hasprefic ("meat") {

++acount

}

}

println ("Here are \ (acount) head carnivores")

Converting string case

Let normal = "could to help me"

Let Shoty = normal.uppercasestring//Uppercase

Let whispered = normal.lowercasestring//lowercase

The string encoding output is printed using the C language

. UTF8. utf16

Unicode scalar

. unicodescalars

Put a space on the output

For scalar in Dogstring.unicodescalars

{

Print ("\ (scalar)")

}

Swift Basics-2