Scala Basics 03: Arrays

Scala array

Fixed-length arrays

Declares the basic format of an array:

Val arr = new Array[t] (N)

Cases:

Val nums = new Array[int] (10)

Val STRs = new Array[string] (10)

When an array declaration is not given a value, it is initialized and can be assigned to the member of the group after initialization.

Array member initialization, such as type int, is initialized to NULL for the 0,string type.

Assigning a value directly to an array

Basic format:

Val arr = Array (x1,x2,.... xn);

Cases:

val s = Array ("Hello", "World")

Accessing array elements

Use () instead of [] to access the element.

Assigning a value to an array element

S (1) = "Scala"

Variable-length arrays

Using variable-length arrays requires the introduction of packages:

Import Scala.collection.mutable.ArrayBuffer

Declares an empty array cache, at which point B is an all-empty array with an array length of 0.

Val B = Arraybuffer[int] ()

Adds an element "1" to the tail of the array.

B+=1

Adds a series of elements "2,3" at the end of the array.

b+= (2,3)

Adds an array of elements (5,8,13,21) to the tail of the B array.

B++=array (5,8,13,21)

Removing the last 3 elements

B.trimend (3)

Inserts an element before the element with the mark bit 2.

B.insert (2,-2)

Inserts a series of elements before the element that marks bit 2.

B.insert (2,-3,-5)

Removes an element with a mark bit of 3.

B.remove (3)

Removes 2 elements by removing the element with the mark bit 1 and beyond.

B.remove (ON)

Converts the variable-length array to a fixed-length array.

Val C = B.toarray

Convert a fixed-length array to a variable-length array

Val d = C.tobuffer

Iterating through an array

Iterate by array ordinal.

for (i <-0 until a.length) {

println (i+ ":" +a (i))

}

Iterate directly over the members of the array (this is a better practice)

For (i <-array) {

println (i)

}

Get members by iterating over the array's subscript

for (i <-0 to (c.length-1) {

println (C (i))

}

Traverse each of the two elements in one line

for (i <-0 to (c.length,2)) {

println (C (i))

}

Reverse traversal

For (i-<-(0 to C.length). Reverse) {

println (C (i))

}

By enumerating the array members with a For statement, you can implement a variety of array controls, such as adding 1 to the array members and generating a new array:

Val new=for (i <-C) yield i+1

This array generation corresponds to the original array type (fixed length/variable length)

Multidimensional arrays

Val matrix = array.ofdim[double] (3,4)//three rows, four rows

Val triangle = new Array[array[int]] (10)

for (i <-0 until Triangle.length)

Fixed-length arrays and variable-length arrays

The use of fixed-length arrays is more encouraged for Scala.

Scala Basics 03: Arrays