Array initialization in Go - Step-by-Step Execution

Concept Flow - Array initialization

Declare array variable

↓

Specify array size

↓

Assign values to elements

↓

Array ready to use

This flow shows how an array is declared with a fixed size and then each element is assigned a value before use.

Execution Sample

Go

package main

import "fmt"

func main() {
    var arr [3]int
    arr[0] = 10
    arr[1] = 20
    arr[2] = 30
    fmt.Println(arr)
}

This code declares an integer array of size 3, assigns values to each element, and prints the array.

Execution Table

Step	Action	Array State	Output
1	Declare array 'arr' of size 3 with default values	[0 0 0]
2	Assign arr[0] = 10	[10 0 0]
3	Assign arr[1] = 20	[10 20 0]
4	Assign arr[2] = 30	[10 20 30]
5	Print arr	[10 20 30]	[10 20 30]

💡 All elements assigned, array printed, program ends.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
arr	[0 0 0]	[10 0 0]	[10 20 0]	[10 20 30]	[10 20 30]

Key Moments - 3 Insights

Why does the array start with zeros before assignment?

In Go, arrays are initialized with zero values for their type automatically, as shown in step 1 of the execution_table.

Can we assign values beyond the declared size of the array?

No, the array size is fixed at declaration. Trying to assign beyond index 2 (for size 3) will cause a compile-time error.

What happens if we print the array before assigning any values?

The array will print with all zero values, as seen in step 1 where arr is [0 0 0].

Visual Quiz - 3 Questions

Look at the execution_table, what is the array state after step 3?

A [10 20 0]

B [10 0 0]

C [0 0 0]

D [10 20 30]

💡 Hint

Check the 'Array State' column in row with Step 3 in execution_table.

At which step is the array printed?

A Step 2

B Step 4

C Step 5

D Step 1

💡 Hint

Look for the 'Print arr' action in execution_table.

If we remove the assignment at step 4, what would be the final array state?

A [10 20 30]

B [10 20 0]

C [0 0 0]

D [10 0 0]

💡 Hint

Refer to variable_tracker and see the effect of skipping step 4 assignment.

Concept Snapshot

Array initialization in Go:
- Declare with fixed size: var arr [3]int
- Elements start with zero values
- Assign values by index: arr[0] = 10
- Size cannot change after declaration
- Use fmt.Println(arr) to print entire array

Full Transcript

This example shows how to create an array in Go. First, we declare an array named arr with size 3. Go automatically fills it with zeros. Then, we assign values 10, 20, and 30 to each element by their index. Finally, we print the array, which outputs [10 20 30]. Arrays have fixed size, so you cannot add more elements than declared.