Section 3 of 12

Arrays, Slices & Maps

Learn collection types for storing and organizing data

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Section 3 of 12

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Tutorials

Arrays

Arrays are fixed-size collections of elements of the same type.

Code Examples

Array Basicsgo
package main

import "fmt"

func main() {
    // Array with fixed size
    var arr [5]int
    arr[0] = 1
    arr[1] = 2
    
    // Array initialization
    names := [3]string{"Alice", "Bob", "Charlie"}
    
    // Get array length
    fmt.Println(len(names))
    
    // Iterate
    for i, name := range names {
        fmt.Printf("%d: %s\n", i, name)
    }
}

Slices

Slices are dynamic, flexible views into arrays. They're more commonly used than arrays in Go.

Code Examples

Slice Operationsgo
package main

import "fmt"

func main() {
    // Create slice
    var slice []int
    slice = append(slice, 1, 2, 3)
    
    // Slice literal
    numbers := []int{10, 20, 30, 40, 50}
    
    // Slicing
    sub := numbers[1:4]  // [20, 30, 40]
    fmt.Println(sub)
    
    // Make with capacity
    s := make([]string, 0, 5)
    s = append(s, "Go", "is", "awesome")
    fmt.Println(s, len(s), cap(s))
    
    // Copy
    dest := make([]int, len(numbers))
    copy(dest, numbers)
}

Maps

Maps are unordered collections of key-value pairs, similar to dictionaries or hash maps.

Code Examples

Map Basicsgo
package main

import "fmt"

func main() {
    // Map literal
    ages := map[string]int{
        "Alice": 25,
        "Bob":   30,
        "Charlie": 35,
    }
    
    // Access
    fmt.Println(ages["Alice"])
    
    // Add/Update
    ages["David"] = 40
    
    // Delete
    delete(ages, "Bob")
    
    // Check if key exists
    age, exists := ages["Alice"]
    if exists {
        fmt.Println("Age:", age)
    }
    
    // Iterate
    for name, age := range ages {
        fmt.Printf("%s: %d\n", name, age)
    }
}

Exercises

Student Grade Tracker

Use a map to store student names and grades, then calculate the average

INTERMEDIATE

Starter Code:

package main

import "fmt"

func main() {
    grades := map[string]int{
        "Alice": 95,
        "Bob": 87,
        "Charlie": 92,
    }
    
    // TODO: Calculate average grade
    // TODO: Print average and all grades
}

Hands-on Project

Contact Management System

Build a simple contact management system using maps and slices

INTERMEDIATE

Learning Objectives

  • >Use maps and slices together
  • >Add/remove items
  • >Search and filter data

Project Tips

  • > Start by understanding the requirements
  • > Break the project into smaller tasks
  • > Test your code frequently as you build
  • > Add error handling throughout your code
  • > Consider edge cases and validate inputs
  • > Document your code with comments
Control Flow & FunctionsHOMEStructs & Interfaces