clear

Compiler Design — Practical Experiments

Instructions to build and run PE3, PE4, PE5, PE6, and Ass2.
All projects use Flex (lexer), Bison (parser), and g++ (C++11).

---

Prerequisites

Make sure the following tools are installed and available in your PATH:

Tool	Purpose	Install (Windows – MSYS2/MinGW)
g++	C++ compiler	pacman -S mingw-w64-x86_64-gcc
flex	Lexical analyser	pacman -S flex
bison	Parser generator	pacman -S bison
make	Build automation	pacman -S make

Tip: If you're using plain CMD/PowerShell, install these via MSYS2 and add the mingw64/bin folder to your system PATH.

Verify installation:

g++ --version
flex --version
bison --version
make --version

---

Quick Reference

Folder	Experiment	Description	Executable	Test File	Error Test File
PE3/	Symbol Table Construction	Parses C-like code and builds a scoped symbol table	symbol_table.exe	test.c	test_error.c
PE4/	Expression Evaluation with Type Checking	Evaluates arithmetic expressions with type‑mismatch and undeclared‑variable detection	evaluator.exe	test_eval.c	test_error.c
PE5/	AST Generation (Postorder Traversal)	Builds an Abstract Syntax Tree and prints its postorder (reverse‑Polish) traversal	ast_generator.exe	test_ast.c	test_error.c
PE6/	Intermediate Code Generation (Quadruples)	Generates three‑address code in quadruple format (op, arg1, arg2, result)	tac_generator.exe	test_icg.c	test_error.c
Ass2/	Control Flow ICG (if‑else, do‑while)	Combines AST + ICG for control‑flow statements	control_flow.exe	test_control.c	test_error.c

---

How to Build & Run

The steps are identical for every experiment — only the folder name changes.

General Steps

# 1. Navigate to the experiment folder
cd <FOLDER>

# 2. Build the project
make clean
make

# 3. Run with the provided test file
./<executable> <test_file>

---

PE3 — Symbol Table Construction

cd PE3
make clean
make
./symbol_table.exe test.c

What it does: Parses test.c (typedefs, structs, functions, variables with pointer/storage‑class annotations) and prints a formatted symbol table showing name, kind, type, storage class, size, scope, location, and initial value.

Expected output (sample):

==============================================
 SYMBOL TABLE
==============================================
Name           Kind           Type           Storage     Size    Scope   Line:Col    InitVal
----------------------------------------------
MyInt          typedef        int            none        4       0       1:13        null
Point          struct-tag     struct         none        0       0       3:8         null
x              variable       int            auto        4       1       4:9         0
...

⚠️ Error Testing

./symbol_table.exe test_error.c

Errors in test_error.c:

Line	Error	What the Parser Reports
5	int a = 5 — missing semicolon	Syntax Error at line X, col Y: syntax error
10	struct Broken { — missing closing } and ;	Syntax Error — parser never finds the closing brace
13	calculate(...) — missing return type before function name	Syntax Error — parser expects a type specifier (int, float, etc.) before an identifier

---

PE4 — Expression Evaluation with Type Checking

cd PE4
make clean
make
./evaluator.exe test_eval.c

What it does: Declares int and float variables, evaluates expressions like d = a + b * c, and checks for:

• Undeclared variable usage
• Type mismatches in assignments and arithmetic

Expected output (sample):

[Semantic Error] Variable 'e' not declared before use at line 9
[Type Mismatch Error] Cannot assign value of different type to variable 'a' at line 11
[Type Mismatch] Adding different types at line 12

=== Symbol Table ===
...

⚠️ Error Testing

./evaluator.exe test_error.c

Errors in test_error.c:

Line	Error	What the Parser Reports
12	z = 5; — variable z was never declared	[Semantic Error] Variable 'z' not declared before use
15	a = 3.14; — assigning a float literal to an int variable	[Type Mismatch Error] Cannot assign value of different type to variable 'a'
18	b = a + x; — adding int (a) and float (x)	[Type Mismatch] Adding different types
21	a = b / 0; — division by zero	[Math Error] Division by zero!

---

PE5 — AST Generation (Postorder / Reverse Polish)

cd PE5
make clean
make
./ast_generator.exe test_ast.c

What it does: Parses arithmetic expressions and assignments, builds an AST for each statement, and prints its postorder traversal (reverse Polish notation).

Expected output (sample):

==============================================
 AST POSTORDER (REVERSE POLISH) GENERATOR
==============================================

Postorder Traversal: 5 3 +

Postorder Traversal: 5 3 2 * +

Postorder Traversal: 5 3 + 2 *

Postorder Traversal: d a b c * + =

⚠️ Error Testing

./ast_generator.exe test_error.c

Errors in test_error.c:

Line	Error	What the Parser Reports
8	b = 5 + * 3; — two operators in a row, missing operand between + and *	Syntax Error at line 8: syntax error
11	c = (5 + 3; — opening ( with no matching )	Syntax Error at line 11: syntax error
14	d = a + b — missing semicolon at end of statement	Syntax Error — parser expects ; but hits end‑of‑file

Note: The first valid statement a = 5 + 3; will still produce correct output before the parser encounters the errors.

---

PE6 — Intermediate Code Generation (Quadruples)

cd PE6
make clean
make
./tac_generator.exe test_icg.c

What it does: Generates three‑address code in quadruple format for each statement.

Expected output (sample):

================================
 INTERMEDIATE CODE (QUADRUPLES)
 Format: (op, arg1, arg2, result)
================================
(*, b, c, t0)
(+, a, t0, t1)
(=, t1, _, d)
--------------------------------
(+, x, y, t0)
(-, x, y, t1)
(*, t0, t1, t2)
(/, t2, 2, t3)
(=, t3, _, result)
--------------------------------

⚠️ Error Testing

./tac_generator.exe test_error.c

Errors in test_error.c:

Line	Error	What the Parser Reports
8	x = ; — empty right‑hand side, no expression after =	Syntax Error at line 8: syntax error
11	y = a + + b; — double operator, missing operand between + and +	Syntax Error at line 11: syntax error
14	z = (a + b * c; — unmatched opening parenthesis	Syntax Error at line 14: syntax error

Note: The first valid statement d = a + b * c; will generate correct quadruples before errors are hit.

---

Ass2 — Control Flow ICG (if‑else & do‑while)

cd Ass2
make clean
make
./control_flow.exe test_control.c

What it does: Parses if-else and do-while control‑flow constructs, builds an AST, prints a postorder traversal, and then generates intermediate code with labels and gotos.

Expected output (sample):

==============================================
 1. AST POSTORDER TRAVERSAL
==============================================
a b < x 1 = x 2 = IF count count 1 + = count 10 != DO_WHILE SEQ

==============================================
 2. INTERMEDIATE CODE (QUADRUPLES)
==============================================
(if, a < b, _, L0)
(goto, _, _, L1)
(label, _, _, L0)
(=, 1, _, x)
(goto, _, _, L2)
(label, _, _, L1)
(=, 2, _, x)
(label, _, _, L2)
(label, _, _, L3)
(+, count, 1, t0)
(=, t0, _, count)
(if, count != 10, _, L3)
==============================================

⚠️ Error Testing

./control_flow.exe test_error.c

Errors in test_error.c:

Line	Error	What the Parser Reports
5–7	if (...) { ... } — missing the required else branch	Syntax Error — the grammar mandates if (...) { ... } else { ... }
13	} while (count != 10) — missing semicolon ; after do-while	Syntax Error — parser expects ; after the closing )
16	if a < b { — missing parentheses () around the condition	Syntax Error — parser expects ( after if keyword

---

Project Structure

CD/
├── PE3/                         # Symbol Table Construction
│   ├── lexer.l                  # Flex lexer rules
│   ├── parser.y                 # Bison grammar + main()
│   ├── symtab.hpp               # SymbolTable class
│   ├── test.c                   # Sample C input (valid)
│   ├── test_error.c             # Error test input (syntax errors)
│   └── Makefile
│
├── PE4/                         # Expression Evaluator + Type Checking
│   ├── lexer.l
│   ├── parser.y
│   ├── symtab.hpp
│   ├── test_eval.c              # Sample input (valid + semantic errors)
│   ├── test_error.c             # Error test input (semantic errors)
│   └── Makefile
│
├── PE5/                         # AST (Postorder Traversal)
│   ├── lexer.l
│   ├── parser.y
│   ├── ast.hpp                  # ASTNode struct + traversal
│   ├── test_ast.c               # Sample input (valid)
│   ├── test_error.c             # Error test input (syntax errors)
│   └── Makefile
│
├── PE6/                         # Intermediate Code (Quadruples)
│   ├── lexer.l
│   ├── parser.y
│   ├── test_icg.c               # Sample input (valid)
│   ├── test_error.c             # Error test input (syntax errors)
│   └── Makefile
│
└── Ass2/                        # Control Flow (if-else, do-while) + ICG
    ├── lexer.l
    ├── parser.y
    ├── ast.hpp                  # Extended ASTNode with TAC generation
    ├── test_control.c           # Sample input (valid)
    ├── test_error.c             # Error test input (syntax errors)
    └── Makefile

---

Troubleshooting

Problem	Fix
'make' is not recognized	Install make via MSYS2 or use mingw32-make instead
'flex' is not recognized	Add MSYS2's usr/bin to your PATH
'bison' is not recognized	Same as above — ensure MSYS2 bin dirs are in PATH
undefined reference to 'yylex'	Run make clean first, then make (stale generated files)
Permission denied on .exe	You may need to unblock the file or run from an admin terminal
cannot open input file	Make sure you're in the correct folder and the test file exists

---

Custom Test Inputs

You can create your own test files and pass them as arguments:

# Example: custom test for PE6
echo "x = a + b * c - d / e;" > my_test.c
./tac_generator.exe my_test.c

Or run interactively (type expressions, then press Ctrl+Z on Windows or Ctrl+D on Linux to finish):

./tac_generator.exe
d = a + b * c;
^Z

---

Last updated: April 2026