Switch and arrays
Switch
1. Switch multi case
> You can add more than one cases using comma
```swift
let numberOfItems = 3
switch numberOfItems{
case 0:
print("Sorry you dont have any items on cart")
case 1,2:
print("You have less than 2 item on cart")
case 3:
Print("You Have 3 items on cart")
default:
Print("You have more than 4 items on cart")
}
```
2. Switch range matching
> if you need to provide range then uses 3 dots
> if you need to add greater than or less than then 2 dots
```swift
let marks = 65
switch marks{
case 81...100:
print("Excellent")
case 60...80:
print("Good")
case 41...60:
Print("Pass")
case 0..<41:
Print("Fail")
default:
Print("Not defined")
}
```
3. switch fallthrough and break statements
> `fallthorugh`: it will go to next case
> `break`: will exit after that case gets executed
```swift
let errors = 20
switch errors{
case 0...20:
print("you have less than 20% errors")
fallthrough
case 15...50:
print("You have 40% of errors ")
case 60...80:
print("You have more than 60% error")
break
default:
Print("error not defined")
}
```
Arrays
1.
```swift
var grades = ["Excellent", "good", "pass", "fail"]
```
> define the array type `var grades:[Sting]`
> If you try to add integers then it will error out `grade=[2,4,"good",6]`
> Arrays should have same data type
2. Last index of the item
```swift
// Last index of the item
print(grades[grades.count - 1])
```
3. Fetch range of items
> use 3 dots to fetch which act as slices
```swift
// Fetch range of items
print(grades[1...3])
print(grades[1...grades.count - 2])
```
4. Array to store differnet types
> to know the type of array use type(of: T)
```swift
// Array to store differnet types
var multigrade: [Any] = [2,4,"good",6]
print(multigrade)
print(type(of:grades), type(of: multigrade))
```
5. Merging two arrays
> use `+` to merge the two arrays
```swift
// Merge two arrays
var finalarray = multigrade + [3, "excellet", 4]
print(finalarray)
```
6. Append in the array
```swift
// append the data
grades.append("Not defined")
```
7. Inset an item
> use insert function with `at` parameter position to where the item need to be inserted
```swift
// insert at particular position
multigrade.insert("Excellent", at: 0)
print(multigrade)
```
8. Delete an item
```swift
// remove an item from array
multigrade.remove(at: 1)
```
9. Insert over range
```swift
// Insert over range
multigrade[1...multigrade.count-1] = ["good", "pass", "fail"]
print(multigrade)
```
10. Mutable and immutable
> use `let` --> to achive immutable\
> use `var` --> to achieve Mutable
```swift
let weekends = ["Saturday", "Sunday"]
weekends.append("Monday") // error: cannot use mutating member on immutable value: 'weekends' is a 'let' constant
weekends[0] = "Monday" // error: cannot assign through subscript: 'weekends' is a 'let' constant
```
