Simple Interpreter

This program is a simple interpreter for a subset of the C programming language, specifically designed to handle basic operations such as integer and string variable declarations, assignments, arithmetic operations, string concatenations, and input/output operations. The program processes the input line by line and maintains a symbol table to keep track of declared variables.

Features

• Integer and String Declarations: Supports the declaration of integer and string variables.
• Assignment Operations: Handles assignments for both integer and string variables.
• Arithmetic Operations: Supports basic arithmetic operations (+, -, *, /) on integer variables.
• String Concatenation: Allows concatenation of string variables.
• Input and Output: Supports scanf for user input and print for output.

Input Syntax

The interpreter recognizes the following commands:

1. Integer Declaration and Assignment

• Syntax: int <variable_name> = <expression> or int <variable_name>
• Example:

  int a = 5
  int b = a + 3
  int c

2. String Declaration and Assignment

• Syntax: string <variable_name> = "<value>" or string <variable_name>
• Example:

  string s = "hello"
  string t = s + " world"
  string u

3. Arithmetic Operations

• Syntax: <variable_name> = <expression>
• Example:

  int x = a + b * 2

4. String Concatenation

• Syntax: <variable_name> = <string_expression>
• Example:

  string greeting = "hello" + " world"

5. Print Statement

• Syntax: print <variable_name>
• Example:

  print a
  print greeting

6. Scanf Statement

• Syntax: scanf <variable_name>
• Example:

  scanf a
  scanf s

7. Exit Command

• Syntax: exit
• Description: Terminates the interpreter.

Error Handling

The interpreter provides basic error handling, including:

• Undefined Variables: Reports an error if a variable is used before it is declared.
• Uninitialized Variables: Reports an error if a variable is used before it is initialized.
• Type Mismatch: Reports an error if operations are attempted between incompatible types (e.g., adding a string and an integer).
• Division by Zero: Reports an error if an attempt is made to divide by zero.

Running the Program

1. Compile the program using a C compiler:

   gcc sample.c -o interpreter

2. Run the interpreter:

   ./interpreter

3. Start typing commands as per the syntax described above. The interpreter will continue to process commands until you type exit.

Example Usage

>>> int a = 10
>>> int b = 20
>>> int c = a + b
>>> print c
30
>>> string s = "Hello"
>>> string t = s + " World"
>>> print t
Hello World
>>> scanf c
Enter value for c: 50
>>> print c
50
>>> exit

Limitations

• The interpreter currently supports only basic integer arithmetic and string concatenation.
• No support for floating-point numbers or complex data types.
• No support for control structures (e.g., loops, conditionals).