Nim Arrays With Examples

Arrays contain a group of elements of the same data type, declared with a single variable name.

The array contains a fixed size of length.

Important points about Nim Arrays

Arrays contain a collection of elements of the same data type
Fixed-size
Array index always starts with 0 and ends with length -1
Index can also contain not only numbers but other ordinal types such as chars, strings

Let’s see different examples.

How to declare Arrays in Nim

Array declaration syntax

var variable: array[size, datatype]

Size is the number of elements in size. Datatype is a NIM predefined type. the array is a keyword variable is a valid identifier

Examples of declaring an array of different

An array of integers is declared with a fixed size and elements in the array are initialized with zero.

var numbers: array[10, int]
echo numbers

Output:

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

An array of floats are declared with a fixed size and elements in the array are initialized with default float zero.

var numbers: array[10, float]
echo numbers

Output:

[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

An array of Strings is declared with size and elements in an array assigned with space.

var numbers: array[10, string]
echo numbers

Output:

["", "", "", "", "", "", "", "", "", ""]

An array of bool is declared with size and elements in an array assigned with a false value.

var numbers: array[10, bool]
echo numbers

Output:

[false, false, false, false, false, false, false, false, false, false]

Another way to declare an array with a dots operator

var ab: array[0..3, int]
echo ab

Output:

[0, 0, 0, 0]

Array elements are accessed using an indexing mechanism.

The first element in the array starts with zero and the last element is length -1.

var numbers: array[5, int]
echo numbers[0] ## 0
echo numbers[4] ## 0
echo numbers[5] ##  Error: index 5 not in 0 .. 4

Another way to get Start and End indexes using low and high procs

echo numbers.low ##0
echo numbers.high ##4

len proc returns the number of elements in an array.

var numbers: array[15, int]
echo numbers.len

Elements are added to an array using an index with square bracket syntax.

array[index]=value

For example, to add an array at the index position, use array[0]=1

Here is an example

var numbers: array[15, int]
echo numbers
numbers[0]=1
numbers[1]=2
numbers[2]=3
echo numbers

Multi-dimensional arrays are arrays of sub-arrays.

Example multi-dimensional are two-dimensional arrays i.e matrix.

var matrix: array[2, array[2, int]]
echo matrix

matrix[0][0] = 10
matrix[0][1] = 11
matrix[1][0] = 12
matrix[1][1] = 13
echo matrix

Output:

[[0, 0], [0, 0]]
[[10, 11], [12, 13]]

Arrays elements iterated using for in loop syntax.

The below example iterates an array using value.

var ab: array[0..2, int]

for value in ab:
  echo value

Output:

0
0
0

For loop contains an object that contains the index and value for each iteration.

var numbers: array[0..2, int]
for index, value in numbers:
  echo index,"=", value

Output:

0=0
1=0
2=0