OldPhonePad

A C# program that simulates the behavior of a old-school mobile phone keypad — supporting multi-tap text input, backspace, and send functionality. Input is provided via command-line arguments and converted into readable text.

---

📝Description

OldPhonePad is a C# console application that emulates the functionality of old-school mobile phone keypads. Users interact with the system using input strings consisting of keypad characters (1-9, 0, *, #), similar to how SMS messages were typed on feature phones.

This project includes both the main program and unit tests to validate input handling and output correctness.

How It Works

• Accepts input as a string of keypad characters: 1234567890*#
• Each key maps to a set of characters:
  • 2 → A B C
  • 3 → D E F
  • 4 → G H I
  • 5 → J K L
  • 6 → M N O
  • 7 → P Q R S
  • 8 → T U V
  • 9 → W X Y Z
  • 0 → space ' '
  • 1 → symbols & ' (
• Pressing a key multiple times cycles through the characters
• Use a space between inputs if two characters are on the same key (e.g., 44 444# → HI)
• * represents backspace
• # represents send and signals the end of input

Features

• Supports input via command-line arguments
• Handles multi-tap behavior for text input
• Includes backspace support with *
• Stops processing input at the # key (send)
• Comes with unit tests for various input scenarios
• Accepts only valid characters: 1 2 3 4 5 6 7 8 9 0 * #

---

💻Requirments

• .NET SDK 6.0 or later
• Make (optional, for using Makefile commands)

---

🚀Getting Started

1. Clone the repository:

$ git clone https://github.com/Shivalux/OldPhonePad.git
$ cd OldPhonePad

2. Build the project:

$ make

• This will generate an executable script: OldPhonePad.sh

3. Run the app:

./OldPhonePad.sh [INPUTS ...]

• Use quotes for inputs containing * or spaces (e.g., "227*#", 22 2#)
• If no input is provided, the program will run using example inputs.

🧰Makefile Commands

Command	Description
make / make all	Build the project and all dependencies
make test	Run the unit test
make clean	Clean the output of a previous build
make fclean	Remove all bin/ and obj/ directory
make re	clean and rebuild entire project

🧪Example

Run the App

Command

$ ./OldPhonePad.sh 33# '227*#' "4433555 555666#" "8 88777444666*664#"

What happens

• Recive input: ["33#, "227*#", "4433555 555666#", "8 88777444666*664#"] as arguments
• Convert each to readable text
• Outputs results to the console

Output

OldPhonePad("33#") => output: |E|
OldPhonePad("227*#") => output: |B|
OldPhonePad("4433555 555666#") => output: |HELLO|
OldPhonePad("8 88777444666*664#") => output: |TURING|

Run Tests

$ make test

Output

Restore complete (0.2s)
  OldPhonePad succeeded (0.1s) → OldPhonePad/bin/Debug/net9.0/OldPhonePad.dll
  OldPhonePad.Tests succeeded (0.1s) → OldPhonePad.Tests/bin/Debug/net9.0/OldPhonePad.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.03]   Discovering: OldPhonePad.Tests
[xUnit.net 00:00:00.06]   Discovered:  OldPhonePad.Tests
[xUnit.net 00:00:00.06]   Starting:    OldPhonePad.Tests
[xUnit.net 00:00:00.10]   Finished:    OldPhonePad.Tests
  OldPhonePad.Tests test succeeded (0.5s)

Test summary: total: 37, failed: 0, succeeded: 37, skipped: 0, duration: 0.5s

👥 Authors & Acknowledments

Created by @Shivalux

⚖️License

This project is licensed under the MIT License.
See the LICENSE file for more information.