UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

University of West Attica · Department of Computer Engineering and Informatics

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Computer Programming

Control Structures

Vasileios Evangelos Athanasiou
Student ID: 19390005

GitHub · LinkedIn

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Supervision

Supervisor: Nikolaos Vassilas, Professor

UNIWA Profile

Co-supervisor: Georgios Meletiou, Laboratory Teaching Staff

UNIWA Profile

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Athens, November 2021

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README

Control Structures

The primary focus of this laboratory work is the theoretical understanding and practical application of control structures in C, specifically:

• if
• if-else
• switch

These structures are essential for directing program flow based on logical conditions and user input.

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Table of Contents

Section	Folder / File	Description
1	assign/	Assignment material
1.1	assign/project3.png	Assignment description / problem statement (English)
1.2	assign/εργασία3.png	Assignment description / problem statement (Greek)
2	docs/	Theoretical documentation
2.1	docs/Control-Structures.pdf	Control structures in C (English)
2.2	docs/Δομές-Ελέγχου.pdf	Control structures in C (Greek)
3	src/	Source code implementations
3.1	src/if.c	Basic conditional statement (if)
3.2	src/if1.c	Extended conditional logic
3.3	src/switch.c	Multi-branch selection (switch)
3.4	src/MaxInteger.c	Maximum value selection using conditionals
3.5	src/2ndGradeEquation.c	Solving a second-degree equation using control logic
4	README.md	Project documentation
5	INSTALL.md	Usage instructions

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1. Theory Fundamentals

The documentation explores the logic and syntax of conditional execution in C.

1.1 if and if-else Statements

• Detailed explanation of how expressions (arithmetic, relational, or logical) are evaluated as:
  • True (non-zero)
  • False (zero)
• Demonstrates how evaluation results determine the execution path of a program.

1.2 Nested Conditions

• Examples of placing if statements inside other if-else structures.
• Used to handle more complex decision-making scenarios, such as:
  • Determining whether a number is negative, positive, or zero.

1.3 switch Statement

• Analysis of integer-based decision-making using:
  • case
  • default
• Emphasizes the critical role of the break statement in preventing unwanted fall-through behavior.

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2. Source Code & Documentation

The project includes fully documented source code for the following programs:

• if.c & if1.c

  • Programs designed to find the maximum of three integers.
  • Implemented using:
    • Nested if-else blocks
    • The ternary operator (?:)

• switch.c

  • Demonstrates how the switch statement operates on integer variables.
  • Shows how execution flows through cases unless explicitly stopped using break.

• 2ndGradeEquation.c

  • A comprehensive program that solves quadratic equations of the form:

$$ ax^2 + bx + c = 0 $$

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3. Detailed Feature: Quadratic Equation Solver

The program 2ndGradeEquation.c performs the following technical functions:

3.1 Input Handling

• Reads three double coefficients (a, b, c) from standard input.

3.2 Mathematical Analysis

• Calculates the discriminant:

$$ D = b^2 - 4ac $$

• Determines whether the equation is:
  • Quadratic (a ≠ 0)
  • Linear / Degenerate (a = 0)

3.3 Root Calculation

• D > 0

  • Calculates two distinct real roots.

• D = 0

  • Calculates one real (double) root.

• D < 0

  • Identifies the equation as impossible in the set of real numbers.

3.4 Output

• Formats and prints:
  • Input coefficients
  • Calculated roots
• Uses high numerical precision for clarity and correctness.