String Calculator Kata - C++ Version

A complete implementation of the famous String Calculator Kata in C++, developed following Test-Driven Development (TDD) principles.

Table of Contents

• Overview
• Quick Start
• Implemented Features
• Project Structure
• How to Use
• Execution Instructions
• Kata Specification
• Test Coverage
• Troubleshooting
• FAQ
• Additional Files
• Credits

Overview

This project implements all steps of the String Calculator Kata, a classic programming exercise that emphasizes test-driven development, incremental refactoring, and clean code writing.

Quick Start

# Clone the repository
git clone https://github.com/morph-eos/cpp-string-calculator-kata.git
cd cpp-string-calculator-kata

# Compile and run
g++ -std=c++11 -o calculator C-String-Calculator-Kata.cpp
./calculator

# Select option 1 and try: 1,2,3,4,5

Implemented Features

✅ Step 1: Basic calculator for 0, 1 or 2 numbers
✅ Step 2: Handle unknown amount of numbers
✅ Step 3: Support for newlines as separators
✅ Step 4: Custom delimiters
✅ Step 5: Negative numbers handling with exceptions
✅ Step 6: Ignore numbers greater than 1000

Project Structure

cpp-string-calculator-kata/
├── add.h                           # Main implementation of add() function
├── C-String-Calculator-Kata.cpp    # Main application with user interface
├── input.txt                       # Input file for manual testing
├── Test-C-String-Calculator-Kata/  # Complete test suite
│   ├── Test-C-String-Calculator-Kata.cpp
│   └── pch.h
├── *.vcxproj                       # Visual Studio project files
└── README.md                       # This documentation

How to Use

Mode 1: Manual Input

1. Run the program
2. Select option 1
3. Enter the number string to calculate

Mode 2: File Input

1. Modify the input.txt file with your string
2. Run the program
3. Select option 2

Valid Input Examples

""          // Result: 0
"1"         // Result: 1
"1,2"       // Result: 3
"1,2,3,4,5" // Result: 15
"1\n2,3"    // Result: 6 (newline + comma)
"//;\n1;2"  // Result: 3 (custom delimiter)
"2,1001"    // Result: 2 (1001 ignored)

Note: When testing custom delimiters manually, the format //;\n1;2 should be entered as a single line. For multiline inputs, use the file input mode.

Execution Instructions

Prerequisites

• C++ compiler compatible with C++11 or higher
• C++ IDE (Visual Studio, Visual Studio Code, Code::Blocks, etc.)
• Microsoft Unit Testing Framework (for running tests)

Compilation and Execution

With Visual Studio

1. Open the C-String-Calculator-Kata.sln file
2. Build the project (Build → Build Solution)
3. Run the application (Debug → Start Without Debugging)

With GCC/Clang

# Compilation (GCC)
g++ -std=c++11 -o calculator C-String-Calculator-Kata.cpp

# Compilation (Clang on macOS)
clang++ -std=c++11 -o calculator C-String-Calculator-Kata.cpp

# Execution
./calculator

Running Tests

With Visual Studio:

1. Open the test project in Visual Studio
2. Go to Test → Run All Tests
3. Verify that all tests pass

Manual Testing (without Visual Studio):

1. Compile and run the main application
2. Test various input scenarios from the examples section
3. Verify outputs match expected results

Example Test Scenarios:

# Test basic functionality
echo -e "1\n1,2,3" | ./calculator

# Test negative numbers (should show error)
echo -e "1\n1,-2,3" | ./calculator

# Test large numbers (should ignore >1000)
echo -e "1\n2,1001,3" | ./calculator

Kata Specification

Step 1: The simplest thing

Create a simple String calculator with a method int add(String numbers).

• The string argument can contain 0, 1 or 2 numbers and will return their sum
• For an empty string it will return 0
• Examples: "", "1", "1,2"

Step 2: Handle an unknown amount of numbers

Allow the add() method to handle an unknown amount of numbers.

Step 3: Handle new lines between numbers

Allow the add() method to handle new lines between numbers (instead of commas).

• This input is valid: "1\n2,3" (result: 6)
• This input is NOT valid: "1,\n"

Step 4: Support different delimiters

Support different delimiters: to change a delimiter, the beginning of the string will contain a separate line that looks like this:

"//[delimiter]\n[numbers...]"

For example "//;\n1;2" should return 3 where the default delimiter is ';'.

The first line is optional. All existing scenarios should still be supported.

Step 5: Negative numbers

Calling add() with a negative number will throw an exception "negatives not allowed" - and the negative that was passed.

For example add("1,4,-1") should throw an exception with the message "negatives not allowed: -1".

If there are multiple negatives, show all of them in the exception message.

Step 6: Ignore big numbers

Numbers bigger than 1000 should be ignored, so adding 2 + 1001 = 2

Test Coverage

The project includes a comprehensive test suite that covers:

• ✅ Empty string
• ✅ Single number
• ✅ Two numbers
• ✅ Unlimited number of numbers
• ✅ Newlines as separators
• ✅ Custom delimiters
• ✅ Negative numbers handling
• ✅ Ignore numbers > 1000

Troubleshooting

Common Compilation Issues

Missing headers: If you get compilation errors about missing headers, ensure you have:

• <string> for string operations
• <sstream> for string stream parsing
• <stdexcept> for exception handling
• <iostream> and <fstream> for I/O operations

C++11 Standard: Make sure to use the -std=c++11 flag when compiling.

Runtime Issues

File not found: If you get "Error opening the input.txt file", make sure the file exists in the same directory as the executable.

Invalid conversion: If you get conversion errors, check that your input contains only valid numbers and delimiters.

FAQ

Q: What happens if I enter non-numeric characters?

A: The program will throw a std::invalid_argument exception during conversion.

Q: Can I use multiple delimiters in the same string?

A: No, the format supports only one custom delimiter per string. However, you can combine the custom delimiter with newlines.

Q: Why are numbers > 1000 ignored?

A: It's part of the kata specification to demonstrate handling of specific business rules.

Q: How can I add new tests?

A: Modify the Test-C-String-Calculator-Kata.cpp file and add new TEST_METHOD methods.

Q: Does the program support decimal numbers?

A: No, it currently supports only integers.

Additional Files

• EXAMPLES.md - Detailed practical examples
• CONTRIBUTING.md - Guide for contributing to the project

Credits

Original kata created by Roy Osherove.