Calculator

A console application that functions as a calculator. It handles very large numbers (results up to about 10⁷ digits). The main goal of the project was to practice manual memory management.

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1. Running the Program

• The program is a plain console app—an executable named kalk.exe. You can launch it by double-clicking the file.
• Alternatively, run it from the command line by typing:

  kalk.exe
  

• You can also start it from any IDE that supports console executables.
• In the same folder as the executable, there should be an input file named in.txt.

Optional argument:

• If you run

  kalk.exe 1
  

  then each operation’s result will be written into its own file (out1.txt, out2.txt, …).
• Otherwise, all answers go into a single file named out.txt.

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2. Handling Invalid Input

The program checks each input token to see if it’s a valid number in the specified base. If it’s not, the output for that operation is

NaN

It also guards against division by zero:

DIVISION_BY_ZERO

Leading zeros (except for the number “0” itself) are treated as an error:

TRAILING_ZEROES

When performing subtraction, if you try to subtract a larger number from a smaller one, it outputs:

SUBTRACTING_BIGGER_NUMBER_FROM_SMALLER

In every error case, the program does not abort; it prints the error message and moves on to the next operation in the input file.

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3a. Input Format

All input is read from in.txt. Two modes are supported:

1. Arithmetic operation

   <operator> <base>
   <number1>
   <number2>
   
   <more operations…>
   

   • <operator> ∈ { +, *, /, %, ^, − } (supports exponentiation “^” and subtraction “−”)
   • <base> is an integer in [2 – 19]

2. Base conversion

   <input_base> <output_base>
   <number>
   
   <more conversions…>
   

   • Both bases are integers in [2 – 19].

Note: While the program generally handles LF line endings, it prefers Windows-style CRLF.

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3b. Output Format

By default, results go to out.txt. If you pass the argument 1 to the executable, each operation is written to its own file (out1.txt, out2.txt, etc.).

The format mirrors the input block:

1. Arithmetic operation

   <operator> <base>
   <number1>
   <number2>
   <result>
   
   <more results…>
   

2. Base conversion

   <input_base> <output_base>
   <number>
   <result>
   
   <more results…>
   

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4. Compilation

Compile the program with GCC using optimization level 3:

gcc -O3 -o kalk kalk.c

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5. Program Structure

1. Declare initial variables (including several FILE*) and open the necessary files.
2. In a loop (until an empty line is encountered):
   • Read the line describing either an arithmetic operation with its base or two bases for conversion.
   • Determine whether to perform an arithmetic operation or a base conversion.
   • Read the required number(s).
   • Execute the requested operation.
3. Clean up all allocated memory and close files before exiting.