[SWIFT] Let's understand the for-in statement!

This time, I learned about for-in statements, so I will output them.

• The following content is for the output of the learning content, so there may be errors. Please note

What is a for-in statement?

*** The for-in statement iterates as many times as there are elements, passing each element to the executable statement in sequence. *** ***

The basic writing method is as follows

qiita.rbvar

for element name in sequence{ 
Statements that are repeatedly executed element by element
 }

• Sequence: It means continuous (things), continuous (things), order, order, arrangement, arrangement (do), sequential, arrangement, ordering, etc.

Let's look at a simple example next.

qiita.rbvar

1.let array = [1,2,3]
2.for element in array {

print(element)
}
Execution result
1
2
3

In the above example, the values in the array array are accessed one by one through the constant element.

When enumerating elements of Dictionary <key, Value> type with for-in, the element type is a tuple of type (key, value). For example, a value of type [String: Int] When passed to a for-in statement, the element will be of type (String: Int).

Let's look at a simple example.

qiita.rbvar

let dictionary = ["a": 1,"b": 2]

for (key,value) in dictionary {

print("key:\(key),Value\(value)")
}
Execution result
key: a Value: 1
key: b Value: 2

break statement

The break statement breaks the execution statement and ends the entire repeating statement. For example, it is used when you need to repeat it any more.

Let's look at a simple example.

qiita.rbvar

var containsThree = false
let array = [1,2,3,4,5]

for element in array {
if element == 3 {
  containsThree = true
  break
//Finish when 3 is found
}
print("element:\(containsTwo)")
}
print("containsTwo: \(containsTwo)")

Execution result
element: 3
containsTwo: true

In the above example, it is a program that checks if the array contains 3. Since it is not necessary to repeat the following when 3 is found, the break statement is used to end the repeating statement.

continue statement

The continue statement suspends the execution statement and then continues the subsequent iterations. For example, it is used to skip processing only in specific cases.

qiita.rbvar

var adds = [Int]()
let array = [1,2,3,]

for element in array {
    if element % 2 == 1 {
    adds.append(element)
    continue
}
print("even: \(element)")

}

print("odds:\(adds)")

Execution result
even: 2
adds: [1,3]

In the above example, unlike the break statement, the subsequent iterations are continued, and you can see that all the elements are processed.