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Introduction to GoLang
course content

Course Content

Introduction to GoLang

Introduction to GoLang

1. Getting Started
What is Go Programming Language?Hello WorldComments in GoBasics of VariablesModifying Variable ValuesConstantsBasics of Operators & ExpressionsChallenge: Hello WorldChallenge: Comments in GoChallenge: Basics of VariablesChallenge: Constants
2. Data Types
IntegersFloating-Point NumbersBooleansRunesStringsBasic Type CastingString FormattingChallenge: String Formatting Practice
3. Control Structures
Comparison OperatorsConditional StatementsConditional ChainingLogical OperatorsSwitch StatementFor LoopBreak StatementChallenge: Practicing For Loop
4. Functions
Declaring and Defining FunctionsLocal and Global ScopesPassing Data into the FunctionsReturn Values from FunctionsMultiple Return ValuesPassing Functions as ArgumentsChallenge: Reviewing Concepts of Functions
5. Arrays and Slices
Declaring ArraysAccessing and Modifying Array ElementsSlicesLength vs CapacityMulti-Dimensional ArraysIterating Over ArraysPassing Variable Number of Arguments into FunctionsPassing Arrays into FunctionsChallenge: Finding the Largest Element in a Grid
6. Intro to Structs & Maps
Creating StructsCreating Instances of StructsData in StructsWhat are Maps?Map Declaration and InitializationAccessing Map ValuesDeleting Keys From MapsChallenge: Creating a Structure

bookLength vs Capacity

We can determine the length of an array or a slice using the len function:

go

index

copy

              
12345

            
randomNumbers := [] int { 1, 4, 5, 7, 9, 10, 12 }
fmt.Println(len(randomNumbers)) // Output: 7

numbersSlice := randomNumbers[2:7]
fmt.Println(len(numbersSlice)) // Output: 5

We can determine the capacity of an array or a slice using the cap function:

The length and capacity of an array are always the same. However, for a slice, the capacity might differ from the length. For instance, in the case where a slice is created from an array, the capacity is greater than the length:

go

index

copy

              
1234

            
randomNumbers := [7] int { 1, 4, 5, 7, 9, 10, 12 }
numbersSlice := randomNumbers[1:3]
fmt.Println(len(numbersSlice)) // Output: 2
fmt.Println(cap(numbersSlice)) // Output: 6

The capacity of a slice is the number of elements from the startingIndex of the slice to the end of the original array from which it was created. In the example above, it is 6.

Remember that modifying a slice also modifies the original array. Therefore, in the given example, appending an element (or value) to a slice essentially updates the element next to the slice's ending index in the original array. In other words, it increases the size of the slice and updates the elements of the original array based on the appended elements/values. This will become clearer with an example:

go

index

copy

              
12345

            
randomNumbers := [7] int { 1, 4, 5, 7, 9, 10, 12 }
numbersSlice := randomNumbers[1:3]
fmt.Println(randomNumbers) // Output: [1 4 5 7 9 10 12]
numbersSlice = append(numbersSlice, 20, 30, 40)
fmt.Println(randomNumbers) // Output: [1 4 5 20 30 40 12]

The capacity is useful for determining how many elements we can append to the slice. If we exceed the capacity of the slice, the append function creates and returns a new slice that is not connected to a portion of the original array. Therefore, it becomes detached from the original array.

You can see the following example: the original array remains unchanged even though we appended more elements to its slice:

go

index

copy

              
12345678

            
numbers := [] int { 1, 2, 3, 4 }
numSlice := numbers[1:3]
fmt.Println(numbers) // Outputs: [1 2 3 4]
fmt.Println(numSlice) // Outputs: [2 3]
fmt.Println(cap(numSlice)) // Outputs: 3
numSlice = append(numSlice, 9, 10)
fmt.Println(numSlice) // Outputs: [2 3 9 10]
fmt.Println(numbers) // Outputs: [1 2 3 4]

This happened because the slice had a capacity of 3, which we exceeded. As a result, the append function returned a new slice that no longer references the original array.

What is the correct syntax for appending an element `z` to a slice called `alphabets`?

What is the correct syntax for appending an element z to a slice called alphabets?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 5. Chapter 4
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