Bài giảng Introduction to computer programming - Chapter 7: Arrays
Ho Chi Minh City University of Technology
Faculty of Computer Science and Engineering
Chapter 7: Arrays
Introduction to Computer Programming
(C language)
TS. Võ Thị Ngọc Châu
2017 – 2018, Semester 2
Course Content
C.1. Introduction to Computers and
Programming
C.2. C Program Structure and its
Components
C.3. Variables and Basic Data Types
C.4. Selection Statements
C.5. Repetition Statements
C.6. Functions
C.7. Arrays
C.8. Pointers
C.9. File Processing
2
References
[1] “C: How to Program”, 7th Ed. – Paul
Deitel and Harvey Deitel, Prentice Hall, 2012.
[2] “The C Programming Language”, 2nd Ed.
– Brian W. Kernighan and Dennis M. Ritchie,
Prentice Hall, 1988
and others, especially those on the Internet
3
Content
Introduction
One-dimension arrays
Memory model of a C array
Access to the elements of a C array
Arrays of characters for strings
Multidimensional arrays
Passing arrays to functions
Summary
4
Introduction – Data Types in C
(Recall from Chapter 3)
Built-in data types (primitive/fundamental)
char (signed char), unsigned char
short int, unsigned short, int, unsigned int, long int,
unsigned long int, long long int, unsigned long long
float, double, long double
void
enum (enumerated data associated with integers)
Derived data types
arrays [] of objects of a given type
pointers * to objects of a given type
structures struct containing objects of other types
union containing any one of several objects of
5
various types
Introduction
void main() {
Given a
double positiveNumber[10] = {2, 1, 3, 10, 8, 3, 4, 5, 9, 12};
set of n
positive
numbers,
find the
smallest
one.
Variable declaration
for an array of
doubles.
int n = 10;
double minNumber = positiveNumber[0];
int iteration = 1;
We haven‟t discussed
it, have we???
while (iteration < n) {
if (minNumber <= positiveNumber[iteration])
iteration = iteration + 1;
else {
minNumber = positiveNumber[iteration];
iteration = iteration + 1;
}
(Chapter 1 –
}
Real code in C)
}
6
Introduction
In your exercise for practice, B.6, chapter
3, you are asked to recommend the nearest
place from 4 given places to student B
based on his/her current location.
How did you implement those?
What happens if there are 20 places for recommendation?
7
Introduction
In our real world, our problem is related to
not only a single object of interest but also
a set of objects of interest.
Example 1: grade a list of submissions of each
of you for every chapter
Example 2: recommend the most relevant place
to visit from a list of places in a city
Example 3: sort a list of suppliers based on their
transaction‟s values
Example 4: find a suitable topic among a list of
topics for your assignment
8
…
Introduction
Array
A means to represent collections in our real world
A data structure consisting of related data items of
the same type
A group of contiguous memory locations that all
have the same type
An array remains the same size throughout its existence.
Suppliers
lstSupplier in memory
id
A C T I V E S F O R
1 2 3 8 3 4 7 2 9 6
value
struct supplier lstSupplier[10];
9
Real world vs. computer‟s world
Introduction
Array
A means to represent collections in our real world
A data structure consisting of related data items of
the same type
A group of contiguous memory locations that all
have the same type
An array remains the same size throughout its existence.
The 1st supplier
The 6th supplier
The 10th supplier
Suppliers
lstSupplier in mry
id
A C T I V E S F O R
1 2 3 8 3 4 7 2 9 6
value
struct supplier lstSupplier[10];
10
Real world vs. computer‟s world
One-dimension arrays
A one-dimension array is the simplest type of
array in C.
type_name variable_name[constant_expressionopt] =opt {expression_list}opt;
variable_name: a valid identifier for a collection
type_name: a valid data type
Basic data type name, derived data type name, or new
name of some existing data type
constant_expressionopt: optional, if specified, an
integer expression used for a size of the array
showing the number of objects of interest in the collection
expression_list: optional, a list of expressions
separated by comma for initialized values
11
One-dimension arrays
A one-dimension array is the simplest type of
array in C.
type_name variable_name[constant_expressionopt] =opt {expression_list}opt;
Example 1: an array of 15 integer numbers to represent the number
of products bought by 15 customers
numProduct in memory
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
int numProduct[15];
12
One-dimension arrays
A one-dimension array is the simplest type of
array in C.
type_name variable_name[constant_expressionopt] =opt {expression_list}opt;
Example 2: an array of 10 doubles to represent 10 positive numbers
positiveNumber in memory
2
1
3 10 8
3
4
5
9 12
double positiveNumber[10];
13
One-dimension arrays
A one-dimension array is the simplest type of
array in C.
type_name variable_name[constant_expressionopt] =opt {expression_list}opt;
Example 3: an array of 10 elements of struct supplier to represent
10 suppliers
lstSupplier in memory
id
A C T I V E S F O R
1 2 3 8 3 4 7 2 9 6
value
14
struct supplier lstSupplier[10];
Memory model of a C array
When defined, an array can be:
A global variable,
A local variable,
A static local variable,
A dynamic local variable, …
It will be organized with a fixed size in an appropriate
corresponding memory segment (.data, .bss, stack, heap).
Regardless of its memory segment, an array is a group of
contiguous memory locations that all have the same type.
Array name is the address of the first location among these contiguous
memory locations.
positiveNumber in memory
positiveNumber is the address of
2
1
3 10 8
3
4
5
9 12
the first double memory location.
double positiveNumber[10];
15
Memory model of a C array
8 bytes
8 byte8s bytes8 bytes
positiveNumber in memory
2
1
3 10 8
3
4
5
9 12
double positiveNumber[10];
16
Memory model of a C array
Array name is the address of the first location among
these contiguous memory locations.
Therefore, assignment for an entire array is not valid!!!
a = {4, 2, 9, -8, 0}; // INVALID!!!!!!!!!!!!!!
17
Memory model of a C array
intArray in memory
3
0
8
9 -2
int intArray[] = {3, 0, 8, 9, -2};
The compiler determined the size of this
array based on the number of initial values
18
Access to the elements of
a C array
Element access is based on index starting
from 0 (zero) with name[..].
Index for the first element is 0: name[0]
Index for the second element is 1: name[1]
Index for the (i+1)-th element is i: name[i]
Index for the n-th element is n-1: name[n-1]
positiveNumber in memory
2
1
3 10 8
3
4
5
9 12
positiveNumber[0]
double positiveNumber[10];
positiveNumber[5] positiveNumber[9]
19
Access to the elements of
a C array
Element access is based on index with name[..].
intArray in memory
3
0
8
9 -2
int intArray[] = {3, 0, 8, 9, -2};
20
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