CSC 113 Lecture1

CSC-113

Computer Programming

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Text Book

Computer Science

A Structured Approach : Using C++

Lecture Outline

• _{Structure of C++ Program C++}

• _Variables

• _{Escape Sequences}

• _{I/O Statements}

• _Operators

• _{Precedence of Operators}

Writing, Editing,

Compiling and Linking

2. Compiler translates in to machine language.

Writing, Editing,

Structure of a C++

Program

Pre-compiler directive

Pre-compiler directive

Opening brace

Hello World Program

Without namespace Without namespace

Namespace std contains all the classes, objects and

functions of the standard C++ library.

Namespace std contains all the classes, objects and

functions of the standard C++ library.

#include <iostream> int main () {

std::cout << "Hello world!\n"; return 0;

Preprocessor Directives

#include <iostream>

“I want to use a predefined library

called iostream”

Always start with a ‘#’

Directives

using namespace std;

•_{“I want to use objects in a name group}

‘std’ ”

•_{Tells the compiler where to look for names}

in the library

•_{Can deal with the situation where two or}

Main Function

int main()

•_{The main body of the program.}

•_{Compiler first tries to locate}

“main()” to find where to begin the program

Comments

Start of comment

End of comment Start of comment

End of comment

• _{Internal program document}

Variables in C++

• _{Named memory locations that have a type}

• _{Named: identifier}

• _{Type: needs declaration}

• _{What you can do with variables}

Variables and

Identifiers

Memory

Address of memory:

Hard to remember

Variables and Identifiers

Memory

studentID

studentGrade1

studentGrade2

Variables and Identifiers

Memory

studentID

studentGrade

studentName

Naming

Identifiers

• _{Allowed characters: A-Z, a-z, 0-9, _ (underscore)}

• _{Not allowed to start with a digit. E.g., 3class (x),}

class3(o)

• _{The identifier cannot duplicate a reserved word.}

e.g., if, case, while…

• _{Good names}  descriptive but short

Integer and Floating Point

Types

2 or 4 Bytes

4 Bytes 2 Bytes

8 Bytes

Maximum/Minimum of

Integer Value Type

Type Sign Byte Minimum value Maximum value

short int/short signed 2 -32,768 32,767

unsigned 0 65,535

int (PC) signed 2 -32,768 32,767

unsigned 0 65,535

int (Mainframe) signed 4 -2,147,483,648 2,147,483,647

unsigned 0 4,294,967,295

long int/long signed 4 -2,147,483,648 2,147,483,647

Variable Initialization

• _{Variable declaration ≠ variable initialization}

• _{Should be initialized by a programmer before it is}

used e.g.,

int count;

Constants

• _{Data values that cannot be changed during program}

execution

• _E.g.,

• _3.141592 • _‘d’

Escape Sequence

• _{Escape sequences are used to represent certain special characters}

within string literals and character literals.

Escape

sequence Description

\' single quote

\" double quote

\? question mark

\\ backslash

\a audible bell

\b backspace

\f form feed - new page

\n line feed - new line

\r carriage return

\t horizontal tab

Standard streams

More about

cout

• width(int) function sets the width for printing a value

• _{Only works until the next insertion command comes}

int x = 42;

cout.width(5);

More about

cout

• fill(char) function sets the fill character.

• _{The character remains as the fill character until set}

again.

int x = 42;

cout.width(5); cout.fill(‘*’);

More about

cout

• _{precision (int) sets the number of significant digits}

of float type numbers

float y = 23.1415; cout.precision(1);

cout << y << '\n'; // Outputs 2e+01 cout.precision(2);

More about

cout

• Output Manipulators (not a function)

endl - outputs a new line character, flushes output

dec - sets int output to decimal

hex - sets int output to hexadecimal

oct - sets int output to octal

#include <iomanip.h>

int x = 42;