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

Arrays, Pointers, Files

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, January 2022

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README

Arrays, Pointers, Files

The primary goal of the application is to process a set of numbers and generate all possible combinations of six numbers that satisfy specific user-defined constraints regarding the count of even numbers and the total sum of the combination.

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Table of Contents

Section	Folder / File	Description
1	assign/	Assignment material
1.1	assign/project6_1.png	Assignment 1 description (English)
1.2	assign/project6_2.png	Assignment 2 description (English)
1.3	assign/εργασία6_1.png	Assignment 1 description (Greek)
1.4	assign/εργασία6_2.png	Assignment 2 description (Greek)
2	docs/	Theoretical documentation
2.1	docs/Arrays-Pointers-Files.pdf	Arrays, pointers, and file handling (English)
2.2	docs/Πίνακες-Δείκτες-Αρχεία.pdf	Arrays, pointers, and file handling (Greek)
3	src/	Source code implementations
3.1	src/Combinations.c	Example using pointers and arrays for combinations
4	README.md	Project documentation
5	INSTALL.md	Usage instructions

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1. Combinations.c

The Combinations.c program includes the following core functionalities:

1.1 Dynamic Data Input

• Reads a set of N numbers (where 6 < N ≤ 49).
• Ensures numbers fall within the valid range [1,49].

1.2 Constraint Setting

• Users can define filtering intervals for combinations:
  • Even Numbers: Interval [X1,X2] for allowed number of even digits.
  • Sum Range: Interval [Y1,Y2] for the allowed total sum.

1.3 Memory Management

• Uses dynamic memory allocation (malloc, calloc) for all major data structures.
• Includes safety checks to verify successful memory binding.

1.4 Data Processing

• Sorts input numbers in ascending order before generating combinations.
• Calculates frequency of occurrence for each number in the filtered list.
• Reports statistics on how many combinations were filtered out by each condition.

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2. Program Structure

The program is modular, consisting of specialized functions:

• Read_N_Numbers(): Handles input for the total count of numbers.
• Read_Matrix(): Populates a dynamically allocated array with the user's numbers.
• Combos(): Core logic engine that generates combinations and applies filters.
• Search_Evens() & Search_Sum(): Validate the defined constraints.
• Frequency(): Tracks how often numbers appear in valid combinations.
• Free_Memory(): Frees all dynamically allocated memory upon completion.

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3. Technical Specifications

• Language: C
• Libraries: stdio.h (I/O operations), stdlib.h (memory management)
• Data Structures: Dynamically allocated one-dimensional arrays (pointers)

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4. Example Usage

If a user inputs 8 numbers:

2, 6, 7, 12, 21, 32, 43, 45

and sets:

• Even number limit: 2 to 4
• Sum limit: 21 to 141

the program will:

1. Generate 28 total combinations.
2. Filter combinations based on the constraints.
3. Print the valid combinations and their frequency of occurrence.