Arrays are one of the most fundamental collection types in C#. They allow you to store multiple related values in a single, ordered collection. Whether you're managing days of the week, student grades, or product prices, arrays make data organization and manipulation more efficient.
In this article, we’ll cover:
- What arrays are.
- How to create and initialize them.
- Accessing, modifying, and enumerating array elements.
- A practical example: Building a Weekly Task Manager.
1. What Is an Array?
An array is:
A fixed-size collection: Once created, the size cannot change.
Ordered: Each item in an array has a specific position (index).
Zero-indexed: The first element is at index0, the second at1, and so on.
2. Creating and Initializing Arrays
Example: Storing Days of the Week
string[] daysOfWeek = { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" };
Here:
string[]specifies that the array stores strings.
{ ... }contains the array’s initial values.
Accessing Items
Console.WriteLine(daysOfWeek[0]); // Output: Monday
Modifying Items
daysOfWeek[2] = "Weds"; // Updates Wednesday to Weds
3. Enumerating an Array
You can iterate through an array using a foreach loop:
Example
foreach (string day in daysOfWeek)
{
Console.WriteLine(day);
}
This prints:
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
4. A Practical Example: Weekly Task Manager
Let’s build a Weekly Task Manager. The program will:
- Store tasks for each day of the week.
- Allow the user to view or update tasks.
- Display all tasks for the week.
Step 1: Create the Array
We’ll use a string array to store tasks for each day.
string[] tasks = new string[7]; // 7 days in a week
Step 2: Initialize with Default Tasks
Let’s initialize the array with some default tasks:
tasks[0] = "Gym in the morning";
tasks[1] = "Team meeting";
tasks[2] = "Work on project report";
tasks[3] = "Grocery shopping";
tasks[4] = "Dinner with friends";
tasks[5] = "Family outing";
tasks[6] = "Relax and read a book";
Step 3: Build the Menu
The program will display a menu for the user to:
- View tasks.
- Update tasks.
- Display all tasks.
Step 4: Implement the Program
Here’s the full code:
using System;
class WeeklyTaskManager
{
static void Main()
{
// Initialize tasks
string[] tasks = {
"Gym in the morning",
"Team meeting",
"Work on project report",
"Grocery shopping",
"Dinner with friends",
"Family outing",
"Relax and read a book"
};
while (true)
{
Console.WriteLine("\n=== Weekly Task Manager ===");
Console.WriteLine("1. View Task");
Console.WriteLine("2. Update Task");
Console.WriteLine("3. Display All Tasks");
Console.WriteLine("4. Exit");
Console.Write("Choose an option: ");
int option = int.Parse(Console.ReadLine());
if (option == 4) break;
switch (option)
{
case 1:
ViewTask(tasks);
break;
case 2:
UpdateTask(tasks);
break;
case 3:
DisplayAllTasks(tasks);
break;
default:
Console.WriteLine("Invalid option. Please try again.");
break;
}
}
}
static void ViewTask(string[] tasks)
{
Console.Write("Enter the day number (1 for Monday, 7 for Sunday): ");
int day = int.Parse(Console.ReadLine()) - 1;
if (day >= 0 && day < tasks.Length)
{
Console.WriteLine($"Task for {GetDayName(day)}: {tasks[day]}");
}
else
{
Console.WriteLine("Invalid day number.");
}
}
static void UpdateTask(string[] tasks)
{
Console.Write("Enter the day number (1 for Monday, 7 for Sunday): ");
int day = int.Parse(Console.ReadLine()) - 1;
if (day >= 0 && day < tasks.Length)
{
Console.Write($"Enter the new task for {GetDayName(day)}: ");
tasks[day] = Console.ReadLine();
Console.WriteLine("Task updated successfully.");
}
else
{
Console.WriteLine("Invalid day number.");
}
}
static void DisplayAllTasks(string[] tasks)
{
Console.WriteLine("\n=== Weekly Tasks ===");
for (int i = 0; i < tasks.Length; i++)
{
Console.WriteLine($"{GetDayName(i)}: {tasks[i]}");
}
}
static string GetDayName(int index)
{
string[] daysOfWeek = { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" };
return daysOfWeek[index];
}
}
How It Works
View Task:
- User inputs a day number.
- Program retrieves and displays the task for that day.
Update Task:
- User inputs a day number and a new task.
- Program updates the corresponding array element.
Display All Tasks:
- The program iterates through the array and prints each task with its day.
Sample Output
Menu:
=== Weekly Task Manager ===
1. View Task
2. Update Task
3. Display All Tasks
4. Exit
Choose an option:
View Task:
Input: 1
Output: Task for Monday: Gym in the morning
Update Task:
Input: 2, then 7, then Plan next week
Output: Task updated successfully.
Display All Tasks:
=== Weekly Tasks ===
Monday: Gym in the morning
Tuesday: Team meeting
Wednesday: Work on project report
Thursday: Grocery shopping
Friday: Dinner with friends
Saturday: Family outing
Sunday: Plan next week
Key Takeaways
- Arrays are a great choice for managing fixed-size, ordered data.
- Use
foreachfor enumeration and square brackets ([]) for accessing and modifying elements. - Arrays can power real-world applications like task managers, schedules, and more.
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