String-Based C++ Calculator

This is a C++ program that implements string-based arithmetic operations in C++ without converting strings to built-in numeric types

Features

• File Input: Reads pairs of numbers from a user-specified file.
• String-Only Arithmetic: Implements string-only addition, handling positive/negative numbers and decimal alignment.
• Custom Validation: Validates each number string with strict formatting rules ((+|-)A(.B)) without using try-catch or standard conversion functions.
• Error Handling: Detects and reports bad file and invalid number formats.

How to Run

1. Open your terminal and navigate to the lab10 directory.

2. Run the make command:

   make

3. This will use the g++ compiler (with -std=c++11 and -Wall) to build the executable file named calculator.

Once built, you can run the program from your terminal.

4. Execute the program:

   ./calculator

5. The program will then prompt you to enter the name of the file containing the test cases (e.g., input.txt).

Example Usage

$ make
g++ -std=c++11 -Wall -g -o calculator main.cpp

$ ./calculator
Enter a filename: input.txt
Line 1: 123 + 456 = 579
Line 2: 123.456 + +1.0 = 124.456
Line 3: +123 + -123 = 0
Line 4: -50.5 + -100.25 = -150.75
Line 5: Error - Invalid number.
  '-5.' is invalid.
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