Flash cards
Review the key moves
What is the main idea behind Go Arrays?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ = [ lengthPut the learning moves in the order that makes the concept easiest to apply.
Arrays are used to store multiple values of the same type in a single variable, instead of declaring separate variables for each value.
Declare an Array
In Go, there are two ways to declare an array:
Syntax
var
array_name = [ length
]
datatype {
values
} // here length is defined
or
var
array_name = [...]
datatype {
values
}
// here length is inferredSyntax
array_name
:= [ length
]
datatype {
values
} // here length
is defined
or
array_name
:= [...]
datatype {
values
}
// here length is inferredNote
The length specifies the number of elements to store in the array. In Go, arrays have a fixed length. The length of the array is either defined by a number or is inferred (means that the compiler decides the length of the array, based on the number of values ).
Access Elements of an Array
You can access a specific array element by referring to the index number.
In Go, array indexes start at 0. That means that [0] is the first element, [1] is the second element, etc.
Example
package main
import ("fmt")
func main() {
prices := [3]int{10,20,30}
fmt.Println(prices[0])
fmt.Println(prices[2])
}Change Elements of an Array
You can also change the value of a specific array element by referring to the index number.
Example
package main
import ("fmt")
func main() {
prices := [3]int{10,20,30}
prices[2] = 50
fmt.Println(prices)
}Array Initialization
If an array or one of its elements has not been initialized in the code, it is assigned the default value of its type.
Tip
The default value for int is 0, and the default value for string is "".
Example
package main
import ("fmt")
func main() {
arr1 := [5]int{} //not initialized
arr2 := [5]int{1,2} //partially initialized
arr3 := [5]int{1,2,3,4,5} //fully initialized
fmt.Println(arr1)
fmt.Println(arr2)
fmt.Println(arr3)
}Initialize Only Specific Elements
It is possible to initialize only specific elements in an array.
Example
package main
import ("fmt")
func main() {
arr1 := [5]int{1:10,2:40}
fmt.Println(arr1)
}The array above has 5 elements.
- 1:10 means: assign 10 to array index 1 (second element).
- 2:40 means: assign 40 to array index 2 (third element).
Find the Length of an Array
The len() function is used to find the length of an array:
Example
package main
import ("fmt")
func main() {
arr1 := [4]string{"Volvo", "BMW", "Ford", "Mazda"}
arr2 := [...]int{1,2,3,4,5,6}
fmt.Println(len(arr1))
fmt.Println(len(arr2))
}