IT104 Discrete Structures
COMPILATION OF TOPICS
Name: Aina Maree E. Siason
Instructor: Ms. Lisa Rebusa
Table of Contents
Topic Page
1. Arrays 4
2. Statistical Array 8
3. Pointers 10
4. Functions 14
5. Relationship Between Pointers and Arrays 18
6. Passing Pointers to Functions 20
7. Pointers to Functions 21
8. Array of Functions 23
9. Enumeration 25
10. Character Handling Library Functions 27
Introduction
This project aims to create a simplified description of the
topics discussed in our IT104 Discrete Structures class. Using C
programming, data structures and algorithms are particularly
tackled wherein logic and theory are needed in order to create
programs. Topics such as Array, Pointers, and Functions will be
discussed. Arithmetical and logical operators such +, +=, ++,
&, ~ are frequently used to solve various equations.
C programming, which is an imperative programming language, is
one of the most widely used programming languages of all time, and
C compilers are available for the majority of computer
architectures and operating systems. In C, all executable codes are
contained within subroutines, which are called functions.
Functional parameters are always passed by value. Pass-by-reference
is simulated in C explicitly by passing pointer values. The latter
will be discussed thoroughly as we progress further.
For each topic, the theory and the application of theory will be
presented. Under the application of theory the following will be
shown: 1) problem, 2) program code, and 3) sample output.
Arrays
Array in C programming is a data structure that can store a
fixed size sequential collection of elements of the same type. An
array is used to store a collection of data. Thus, it is a
collective name given to a group of similar quantities. These
similar quantities could be the number of students enrolled in a
university, the grades of 100 students enrolled in a class, or the
ages of employees in a company.
All arrays consist of contiguous memory locations. The lowest
address corresponds to the first element and the highest address to
the last element.
First Element Last Element
age[0]
age[1]
age[2]
age[3]
Arrays and pointers have a special relationship because arrays
use pointers to reference memory locations.
Declaration of an Array
Arrays must be declared first before they can be used in a
program. The standard array declaration is as follows:
type arrayname[arraysize];
Type specifies the variable type of the element that is going to
be stored in the array. The following are the basic variable types
in C Language:
Type
Description
char
Typically a single octet (one byte). This is an integer
type.
int
The most natural size of integer for the machine.
float
A single-precision floating value.
double
A double-precision floating value.
void
Represents the absence of type.
Some examples of array declaration are the following:
char name[30];
int min[10];
float width[20];
double height[15];
Arrays and pointers have a special relationship because arrays
use pointers to reference memory locations.
Arrays start at position 0 in C Language. The elements of the
array occupy adjacent locations in memory. C Language treats the
name of the array as if it were a pointer to the first element,
which is important in understanding how to do arithmetic with
arrays.
Single-dimensional Array
The single-dimensional array in C is the simplest form of array
that contains only one row for storing data. It has a single set of
square brackets ([]).
type arrayName[arraySize];
Multi-dimensional Array
The C language supports multi-dimensional arrays. The simplest
data structure for organizing tabular data is a two-dimensional
array. C compilers treat a two-dimensional array as an array of
arrays. To declare a two-dimensional integer array size x,y you
would write something as follows:
type arrayName[x][y];
Where type can be any valid C data type and arrayName will be a
valid C identifier. A two-dimensional array can be think as a table
which will have x number of rows and y number of columns. A
2-dimensional array a, which contains three rows and four columns
can be shown as below:
Thus, every element in array a is identified by an element name
of the form a[i][j], where a is the name of the array, and i and j
are the subscripts that uniquely identify each element in a.
Example Problem
Problem
Forty Students were asked to rate the quality of the food in the
student cafeteria on a scale of 1 to 10 (1 means awful and 10 means
excellent). Place the 40 responses in an integer array and
summarize the results of the poll.
Code
#include
#define RESPONSE_SIZE 40
#define FREQUENCY_SIZE 11
int main()
{
int answer, rating, frequency[ FREQUENCY_SIZE ] = { 0 };
int responses[ RESPONSE_SIZE ] =
{ 1, 2, 6, 4, 8, 5, 9, 7, 8, 10,
1, 6, 3, 8, 6, 10, 3, 8, 2, 7,
6, 5, 7, 6, 8, 6, 7, 5, 6, 6,
5, 6, 7, 5, 6, 4, 8, 6, 8, 10 };
for ( answer = 0; answer
