In this part of the Golang Backend Real-World series, we explore the foundational concepts that power every Go backend application: variables, data types, and constants.
Whether you’re building REST APIs, microservices, or CLI tools, these concepts appear everywhere in real-world Golang code.

1. Variables in Go

Variables store values that can change throughout the lifecycle of a program. Go is statically typed, meaning each variable has a specific type determined at compile time.

1.1 Declaring variables using var

var name string = "Leaf"
var age int = 30

This is the most explicit form of variable declaration in Go.

1.2 Declaring variables without initialization (zero values)

Go assigns a zero value when no initial value is provided:

var message string  // ""
var count int       // 0
var active bool     // false

This prevents undefined or null-type issues.

1.3 Short declaration (:=)

Commonly used inside functions for cleaner code:

title := "Golang Tutorial"
views := 102
enabled := true

Go infers the type automatically.

1.4 Declaring multiple variables

var a, b, c = 1, 2, 3

Or in block format:

var (
    username = "admin"
    attempts = 3
    isAdmin  = false
)

This is useful for grouping related variables.

2. Data Types in Go

Go provides a powerful type system optimized for both performance and readability. Here are the types most relevant to backend systems.

2.1 Numeric types

• int, int8, int16, int32, int64
• uint versions for unsigned integers
• float32, float64 for decimal numbers

Example:

price := 19.99
quantity := 5

2.2 Strings

Go’s strings are UTF-8 encoded:

message := "Hello, Go!"

2.3 Boolean

isValid := true

2.4 Composite Types (important for backend systems)

Slice

roles := []string{"admin", "user"}

Map

config := map[string]string{
    "env": "production",
    "region": "ap-southeast-1",
}

Struct — core building block of backend models

type User struct {
    Name string
    Age  int
}

3. Constants in Go

Constants represent values that never change.

const AppName = "Codevivu.com"
const MaxConnections = 10

3.1 Using iota for enumerations

iota is a counter that increments automatically:

const (
    StatusPending = iota     // 0
    StatusApproved           // 1
    StatusRejected           // 2
)

This is useful for defining business logic states.

4. Summary

In Part 3, you learned:

• Different ways to declare variables in Go
• How zero values work
• Core primitive and composite data types
• How to define constants and enumerations using iota
• Practical examples used in real backend systems