03-Overview of C++ (Part 2)

7/24/2019 03-Overview of C++ (Part 2)

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Data Structure Using C++

Overview of C++ (part 2)


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CT077-3-2-DSTR Data Structures 2

Learning Objective

At the end of the lecture, you would know:

the simple data types in C++

how to declare and manipulate data into arrays

the difference between passing parameters to

functions by value or by reference

how to pass arrays to functions


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C++ Data Type

A data type is called simple if variables of that type can

store only one value at a time

Simple types are also called: Primitive or Built-in Types

Data Type

Simple

Integral

char shortint long

bool

Floating

float doublelong double

Structured

Array

StructUnion

Class


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C++ Data Type

bool type is not supported by all C++ compilers

Can add unsigned modifier before char, short, int, and

long, so that variables of that type are positive always

(maximum storable number gets doubled)

Simple Data Types

Integral

unsigned char unsigned short

unsigned int unsigned long

bool

Floating

float double

longdouble


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C++ Data Type

A structured data type is one in which each data item is acollection of other data items

Very similar to classes, but should be thought of as not

having methods (just data grouping)

Data Type

Simple

Integral

char shortint long

bool

Floating

float doublelong double

Structured

Array

StructUnion

Class


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Arrays

Array: a collection of a fixed number of

components wherein all of the components have

the same data type

In a one-dimensional array, the components arearranged in a list form

Syntax for declaring a one-dimensional array:


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Arrays

Example:

intnum[5];



Accessing Array Components

General syntax:

where indexExp, called an index, is anyexpression whose value is a nonnegative integer

Index value specifies the position of the

component in the array (called random access) The array index always starts at 0




Example:

list [3] = 10;

list [6] = 35;

list [5] = list [3] + list [6];

In memory, array elements

are reserved adjacent to

each other in order toguarantee fast random

access to any element



Array Initialization

Arrays can be initialized during declaration

In this case, it is not necessary to specify the

size of the array

Size determined by the number of initialvalues in the braces

Example:

doublesales[] = {12.25, 32.50, 16.90, 23, 45.68};



Array Initialization

The statement:

intlist[10] = {0};

declares list to be an array of 10 components

and initializes all of them to zero The statement:

int list[10] = {8, 5, 12};

declares list to be an array of 10 components,initializes list[0] to 8, list[1] to 5, list[2] to 12 and

all other components are initialized to 0



Some Restrictions on Array

Processing

Consider the following statements:

C++ does not allow aggregate operations on anarray:

Solution:



Some Restrictions on Array

Processing

The following is illegal too:

Solution:

The following statements are legal, but do not

give the desired results This doesntprint all elements of the array.It prints the memory address of the firstelement (also called base address)

This doesnt compare all elements of

both arrays, but compares the memory

base addresses of the two arrays



Two-Dimensional Arrays

Two-dimensional array: collection of a fixed

number of components (of the same type)

arranged in two dimensions

Sometimes called matrices or tables Declaration syntax:

where intexp1 and intexp2 specify the number of

rows and the number of columns, respectively in

the array



Two-Dimensional Arrays

Example:

doublesales [10][5];




Syntax:

where indexexp1 and indexexp2 are expressionsyielding nonnegative integer values, and specify

the row and column position

2D arrays are also specially arranged in memory

as adjacent rows, so that fast random access to

any element (any row, any column) is guaranteed




Example:

sales [5][3] = 25.75;


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Two-Dimensional Array

Initialization

Two-dimensional arrays can be initialized when

they are declared:

Elements of each row are enclosed within

braces and separated by commasAll rows are enclosed within braces

For number arrays, if all components of a row

arent specified, unspecified ones are set to 0


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Passing Parameters to Functions

Value parameter: the formal parameter receives

a copy of the content of corresponding actual

parameter

Reference parameter: the formal parameter

receives the location (memory address) of the

corresponding actual parameter

Syntax: put & mark before parameter name


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Example Program

void grow(int&age) {

age = age + 1;

cout


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Example Program - 2

void main() {

int value= 20;

inc (value);

cout


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Example Program - 3


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Example Program - 3


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Summary - Passing Parameters

Value parameter: During program execution, manipulating value parameter

changes its data copy (stored in its own memory space)

The actual parameter stays intact

Reference parameter:

Received address leads to memory space of the

corresponding actual parameter Changing reference parameter affects the actual

parameter


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Reference Parameters

Reference parameters are useful in three

situations:

You want to change the actual parameter

No easy way to return more than one valuefrom a function, so you pass more reference

parameters

When passing the address would save

memory space and time (no copying)


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Arrays as Parameters to Functions

Arrays are passed by reference, always

The symbol & is not used when declaring an

array as a formal parameter

The size of the array is usually omitted If provided, it is ignored by the compiler

Unlike Java, array size must be passed-in to the

function by some means (parameter, etc.)


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Implement examples given in the lecture

Write a: voidswap (int , int) function which

swaps the values of its two given parameters

Homework


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What we will cover next

Overview of C++

Pointers

Passing parameters to functions using pointers

Dynamic Memory Allocation

Very Important Topics

- not to be missed out -

03-Overview of C++ (Part 2)

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