플로우컨트롤. (반복문) for Loop & Where

let closedRange = 0...10  //lowerBound 0, upperBound 10
let halfClosedRange = 0..<10 //lowerBound 0, upperBound 9

var sum = 0
for i in closedRange {
    print("---> \(i)")
    sum += i
}

print("----> total sum: \(sum)")

/*
---> 0
---> 1
---> 2
---> 3
---> 4
---> 5
---> 6
---> 7
---> 8
---> 9
---> 10
----> total sum: 55
*/

let closedRange = 0...10  //lowerBound 0, upperBound 10
let halfClosedRange = 0..<10 //lowerBound 0, upperBound 9

var sum = 0
for i in halfClosedRange {
    print("---> \(i)")
    sum += i
}

print("----> total sum: \(sum)")

/*
---> 0
---> 1
---> 2
---> 3
---> 4
---> 5
---> 6
---> 7
---> 8
---> 9
----> total sum: 45
*/




// -------> Range + for 문 (1)




let closedRange = 0...10 //lowerBound 0, upperBound 10
let name = "Bang"
for _ in closedRange {
    print("i")
}

// -------> Array + for 문 (2)

var shopingList = ["carrot", "potato"]
for i in shopingList {
    print(shopingList[0])
}

 

 

import UIKit

let closedRange = 0...10  //lowerBound 0, upperBound 10

// CGFloat은 하나의 데이터 타입인데 CG 코어그래픽스 개발하다가 종종 볼수 있음

var sinValue: CGFloat = 0
for i in closedRange {
    sinValue = sin(CGFloat.pi/4 * CGFloat(i))
}


// Jason 여러번 프린트하기

let name = "Jason"
for i in closedRange {    // Immutable value 'i' was never used; consider replacing with '_' or removing it
    print("---> name: \(name)")
    
}

/*
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
---> name: Jason
*/

쓰지않는 변수가 있다면 경고가 뜬다. "_"로 변경해서 해결할 수 있다고 한다.

Immutable value 'i' was never used; consider replacing with '_' or removing it

 

 

 

 

for loop 심화

import UIKit

let closedRange = 0...10  //lowerBound 0, upperBound 10



for i in closedRange {
    if i % 2 == 0 {             // %는 앞을 2로 나눴을 때 나머지
        print("---> 짝수: \(i)")
    }
}

/*
---> 짝수: 0
---> 짝수: 2
---> 짝수: 4
---> 짝수: 6
---> 짝수: 8
---> 짝수: 10
*/


// 조금더 깔끔한 버전
for i in closedRange where i % 2 == 0 { //closedRange에서 하나씩 뽑아오는데 오른쪽 을 만족하는 것을 가져온다
    print("---> 짝수: \(i)")
}


// 

import UIKit

let closedRange = 0...10  //lowerBound 0, upperBound 10



for i in closedRange where i % 2 == 0 { //closedRange에서 하나씩 뽑아오는데 오른쪽 을 만족하는 것을 가져온다
    print("---> 짝수: \(i)")
}

for i in closedRange {
    if i == 3{
        continue   // i가 3이면 아래를 뛰어넘어라
    }
    print("---> \(i)")
}


/*
---> 0
---> 1
---> 2
---> 4
---> 5
---> 6
---> 7
---> 8
---> 9
---> 10
*/


// for 루프 중첩사용하기

import UIKit

let halfclosedRange = 1..<10  //lowerBound 1, upperBound 10


//중첩은 너무 많아지면 수행성능도 안좋아지고 가독성도 안좋아서 협업시 싫어할 수 있다.

for i in halfclosedRange {
    for j in halfclosedRange{
        print("gugu -> \(i) * \(j) = \(i * j)")
    }
}



/*
gugu -> 1 * 1 = 1
gugu -> 1 * 2 = 2
gugu -> 1 * 3 = 3
gugu -> 1 * 4 = 4
gugu -> 1 * 5 = 5
gugu -> 1 * 6 = 6
gugu -> 1 * 7 = 7
gugu -> 1 * 8 = 8
gugu -> 1 * 9 = 9
gugu -> 2 * 1 = 2
gugu -> 2 * 2 = 4
gugu -> 2 * 3 = 6
gugu -> 2 * 4 = 8
gugu -> 2 * 5 = 10
gugu -> 2 * 6 = 12
gugu -> 2 * 7 = 14
gugu -> 2 * 8 = 16
gugu -> 2 * 9 = 18
gugu -> 3 * 1 = 3
gugu -> 3 * 2 = 6
gugu -> 3 * 3 = 9
gugu -> 3 * 4 = 12
gugu -> 3 * 5 = 15
gugu -> 3 * 6 = 18
gugu -> 3 * 7 = 21
gugu -> 3 * 8 = 24
gugu -> 3 * 9 = 27
gugu -> 4 * 1 = 4
gugu -> 4 * 2 = 8
gugu -> 4 * 3 = 12
gugu -> 4 * 4 = 16
gugu -> 4 * 5 = 20
gugu -> 4 * 6 = 24
gugu -> 4 * 7 = 28
gugu -> 4 * 8 = 32
gugu -> 4 * 9 = 36
gugu -> 5 * 1 = 5
gugu -> 5 * 2 = 10
gugu -> 5 * 3 = 15
gugu -> 5 * 4 = 20
gugu -> 5 * 5 = 25
gugu -> 5 * 6 = 30
gugu -> 5 * 7 = 35
gugu -> 5 * 8 = 40
gugu -> 5 * 9 = 45
gugu -> 6 * 1 = 6
gugu -> 6 * 2 = 12
gugu -> 6 * 3 = 18
gugu -> 6 * 4 = 24
gugu -> 6 * 5 = 30
gugu -> 6 * 6 = 36
gugu -> 6 * 7 = 42
gugu -> 6 * 8 = 48
gugu -> 6 * 9 = 54
gugu -> 7 * 1 = 7
gugu -> 7 * 2 = 14
gugu -> 7 * 3 = 21
gugu -> 7 * 4 = 28
gugu -> 7 * 5 = 35
gugu -> 7 * 6 = 42
gugu -> 7 * 7 = 49
gugu -> 7 * 8 = 56
gugu -> 7 * 9 = 63
gugu -> 8 * 1 = 8
gugu -> 8 * 2 = 16
gugu -> 8 * 3 = 24
gugu -> 8 * 4 = 32
gugu -> 8 * 5 = 40
gugu -> 8 * 6 = 48
gugu -> 8 * 7 = 56
gugu -> 8 * 8 = 64
gugu -> 8 * 9 = 72
gugu -> 9 * 1 = 9
gugu -> 9 * 2 = 18
gugu -> 9 * 3 = 27
gugu -> 9 * 4 = 36
gugu -> 9 * 5 = 45
gugu -> 9 * 6 = 54
gugu -> 9 * 7 = 63
gugu -> 9 * 8 = 72
gugu -> 9 * 9 = 81
*/

 

 

for loop 와 while loop 를 비교해보자

while문은 Boolean 값이 조건이다.

for는 배열이 들어온다??

 

print("--- while")

var i = 0
while i < 10 {
    print(i)
    i += 1
}

print("--- Repeat")
i = 0
repeat {
	print(i)
	i += 1
} while i < 10


print("--- for 문")

let closedRange = 0...10  //lowerBound 1, upperBound 10
for i in closedRange {