swift学习笔记1

import Cocoa

var someInts:[Int] = [10, 20, 30]

for index in someInts {
    print( "index 的值为 \(index)")
}

for index in 2...10 {
    print("\(index) 乘于 5 为：\(index * 5)")
}

// 使用字符串字面量
var stringA = "Hello, World!"
print( stringA )

// String 实例化
var stringB = String("Hello, World!")
print( stringB )

// 使用字符串字面量创建空字符串
var stringA1 = ""

if stringA1.isEmpty {
    print( "stringA1 是空的" )
} else {
    print( "stringA1 不是空的" )
}

// 实例化 String 类来创建空字符串
let stringB1 = String()

if stringB1.isEmpty {
    print( "stringB1 是空的" )
} else {
    print( "stringB1 不是空的" )
}

let char1: Character = "A"
let char2: Character = "B"

print("char1 的值为 \(char1)")
print("char2 的值为 \(char2)")

for ch in "Runoob" {
    print(ch)
}
var varA:String = "Hello "
let varB:Character = "G"

varA.append( varB )

print("varC  =  \(varA)")

var someInts1 = [Int](repeating: 10, count: 3)

var someVar = someInts1[0]

print( "第一个元素的值 \(someVar)" )
print( "第二个元素的值 \(someInts1[1])" )
print( "第三个元素的值 \(someInts1[2])" )

var someStrs = [String]()

someStrs.append("Apple")
someStrs.append("Amazon")
someStrs.append("Runoob")
someStrs += ["Google"]

for item in someStrs {
    print(item)
}

var intsA = [Int](repeating: 2, count:2)
var intsB = [Int](repeating: 1, count:3)

var intsC = intsA + intsB

for item in intsC {
    print(item)
}

print("intsA.isEmpty = \(intsA.isEmpty)")
print("intsB.isEmpty = \(intsB.isEmpty)")
print("intsC.isEmpty = \(intsC.isEmpty)")