basics of c and c++ by eteaching

C++

IT 3rd Sem

C & C++

Ken Thompson designed B Language [BCPL(Basic Combined

Programming language)]

C was developed in 1970s in Bell Laboratories by Dennis

Ritchie (B language modified)

C was written for UNIX operating system.

History of C Language

History of C++

Language designed by Bjarne Stroutstrup in early 1980s

Named….. C with classes

In 1983, name changes to C++

IT 3rd Sem

C & C++

C++ is superset of C

case-sensitive

Similarities

Differences

classes and objects

C is procedural language whereas C++ is object-oriented

programming language.

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C++Character Set

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Letters A-Z, a-z

Digits 0-9

Special Symbols Space + − * / ^ \ ( ) [ ] { } = !=

< > . ‘ “ , % ! & _ # <= >=

White SpacesBlank Space, Horizontal Tab (→ )

Carriage Return ( ) Newline

Source File

Object File

Tokens

Identifiers

Keywords

Important Terms

IT 3rd Sem

C++

Data Types

IT 3rd Sem

C++

int

2 bytes

range -32768 to +32767 (signed)

range 0 to +65535 (unsigned)

Type Size Range

int 2 -32767 to +32767

unsigned int 2 0 to 65535

signed int 2 -32767 to +32767

short int 2 -32767 to +32767

unsigned short int 2 0 to 65535

signed short int 2 -32767 to +32767

long int 4 -2147483648 to +2147483647

signed long int 4 -2147483648 to +2147483647

unsigned long int 4 0 to +42949667295

IT 3rd Sem

C++

float & double

Type Size Range

float 4 3.4 E-38 to 3.4 E+38

double 8 1.7 E-308 to 1.7 E+308

long double 10 3.4 E-4932 to 1.1 E+4932

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C++

char

Type Size Range

char 1 -128 to +127

unsigned char 1 0 to +255

signed char 1 -128 to +127

void

size 0 bytes

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C++

Variable

Rules

Variable Declaration

data-type var1,var2;

For eg:

int a,b,c;

float x;

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C++

Variable initialization

data-type var1;

var1=value;

For eg:

int a;

a=2;

Method 1:

Method 2:

data-type var1=value;

For eg:

int a=2;

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C++

C++Derived Data Types:

Array

Structure

Union

Enumerations

Pointers

Class

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C++Enumerations:

set of values represented by identifiers

Format:

enum name{var1,var2,var3,----------, varn};

name n1,n2;

n1=var1;

n2=var3;

cout<<n1;

cout<<n2;

output will be 0 and 2

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C++Operators:

Type Operators Meaning

Arithmetic

+ Addition

− Subtraction

* Multiplication

/ Division

% Modulus (Remainder)

Relational

< Less than

> Greater than

<= Less than or equal to

>= Greater than or equal to

== Equal to

!= Not equal to

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C++Operators:


Logical

&& Logical AND

|| Logical OR

! Logical NOT

Bitwise

& Bitwise AND

I Bitwise OR

^ Bitwise Exclusive-OR (XOR)

>> Bitwise Shift Right

<< Bitwise Shift Left

~ Bitwise Complement

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C++Operators:


Assignment

= Assignment

+= a+=b means a=a+b

−= a−=b means a=a−b

*= a*=b means a=a*b

/= a/=b means a=a/b

%= a%=b means a=a%b

>>= a>>=n means a=a>>n

<<= a<<=n means a=a<<n

&= a&=b means a=a&b

|= a|=b means a=a|b

!= a!=b means a=a!b

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C++Operators:


Special

* Pointer

& Address

. Membership

:: Scope Resolution

size of()

?: Ternary Operator

++ Increment (pre and post)

−− Decrement (pre and post)

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C++Operator Precedence:

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Operator(s) Operation(s) Order of evaluation (precedence)

() Parentheses Evaluated first. If the parentheses are nested, the expression

in the innermost pair is evaluated first. If there are several

pairs of parentheses “on the same level” (i.e., not nested),

they are evaluated left to right.

!, +, - Logical NOT, signs Evaluated second. If there are several, they re

evaluated right to left.

*, /, or % Multiplication Division

Modulus

Evaluated third. If there are several, they re

evaluated left to right.

+ or - Addition

Subtraction

Evaluated fourth. If there are several, they are


>, <, >=, <= Relational Operators Evaluated fifth. If there are several, they are


==, != Equality Operators Evaluated sixth. If there are several, they are


&& Logical AND Evaluated seventh. If there are several, they are


| | Logical OR Evaluated eighth. If there are several, they are


C++Expression:

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C++Type Conversion:

Implicit or Automatic

Explicit or type casting

Syntax:

(cast-type) expression;

cast-type (expression);

For eg:

int a,b;

float c;

c = (float) a/b;

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C++Phases of C++

programs:

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C++ PROGRAM DEVELOPMENT GOES THROUGH SIX STEPS:Step1: Edit (using text editor to type, correct and save the program

file).

Step2: preprocessor, automatically before compile, executes to

include other text files in the file to be compiled.

Step3: Compile , the compiler translates the C++ code into machine

language (also called object-code).

Step4: Link , it is linking any used functions that are defined elsewhere

such as standard library functions, or private library for a group of

programmers, linker, links the object code with the code for the missing

functions to provide full code

Step5: Load, a program before executing , must be loaded into the

main memory, loader does this task , loading code from disk.

Step6: Execute, the computer under the control of its CPU executes

the program. Instruction by instruction.

C++IT 3rd Sem

ILLUSTRATION OF C++

PROGRAM PHASES

Phases of C++ Programs:

1. Edit

2. Preprocess

3. Compile

4. Link

5. Load

6. Execute

Loader

main

Memory

Program is created in

the editor and stored

on disk.

Preprocessor program

processes the code.

Loader puts program

in memory.

CPU takes each

instruction and

executes it, possibly

storing new data

values as the program

executes.

CompilerCompiler creates

object code and

stores

it on disk.Linker links the object

code with the libraries,

creates a.out and

stores it on disk

Editor

Preprocessor

Linker

CPU

main

Memory

.

.

.

.

.

.

.

.

.

.

.

.

Disk

Disk

Disk

Disk

Disk

C++Structure of C++ program

IT 3rd Sem

Every C++ program must have a function named main. The programmer

can choose to decompose the program into several parts (user-defined

functions). Think of main as the master and the other functions are the

servants.

The execution always starts with main.

1. Comments

2. Load <iostream.h>

3. main

3.1 Print "Welcome to C++\n"

3.2 exit (return 0)

1 // Fig. 1.2: fig01_02.cpp

2 // A first program in C++

3 #include <iostream.h>

4

5 int main()

6 {

7 cout << "Welcome to C++!\n";

8

9 return 0; // indicate that program ended successfully

10 }

Welcome to C++!

preprocessor directive

Message to the C++ preprocessor.

Lines beginning with # are preprocessor directives.

#include <iostream.h> tells the preprocessor to include

the contents of the file <iostream.h>, which includes

input/output operations (such as printing to the screen).

Comments

Written between /* and */ or following a //.

Improve program readability and do not cause the computer to

perform any action.

C++ programs contain one or more functions, one of which must be main

Parenthesis are used to indicate a function

int means that main "returns" an integer value.

Prints the string of characters contained between the quotation

marks. The entire line, including cout, the << operator, the string

"Welcome to C++!\n" and the semicolon (;), is called a

statement.

All statements must end with a semicolon.

return is a way to exit a function from a

function.

return 0, in this case, means that the

program terminated normally.

A left brace { begins the body of every function

and a right brace } ends it.

C++A Simple Program: Printing a Line of Text

IT 3rd Sem

cout

Standard output stream object

“Connected” to the screen

<<

Stream insertion operator

Value to the right of the operator (right operand) inserted into output stream (which is connected to the screen)

cout << “Welcome to C++!\n”;

\

Escape character

Indicates that a “special” character is to be output

C++A Simple Program: Printing a Line of Text

IT 3rd Sem

Escape Sequence Description

\n Newline. Position the screen cursor to the

beginning of the next line.

\t Horizontal tab. Move the screen cursor to the next

tab stop.

\r Carriage return. Position the screen cursor to the

beginning of the current line; do not advance to the

next line.

\a Alert. Sound the system bell.

\\ Backslash. Used to print a backslash character.

\" Double quote. Used to print a double quote

character.

There are multiple ways to print text

Following are more examples

C++IT 3rd Sem


2. main

2.1 Print "Welcome"

2.2 Print "to C++!"

2.3 newline

2.4 exit (return 0)

Program Output

Welcome to C++!

1 // Fig. 1.4: fig01_04.cpp

2 // Printing a line with multiple statements


4

5 int main()

6 {

7 cout << "Welcome ";

8 cout << "to C++!\n";

9


11 }

Unless new line '\n' is specified, the text continues

on the same line.

C++IT 3rd Sem


2. main

2.1 Print "Welcome"

2.2 newline

2.3 Print "to"

2.4 newline

2.5 newline

2.6 Print "C++!"

2.7 newline

2.8 exit (return 0)

Program Output

1 // Fig. 1.5: fig01_05.cpp

2 // Printing multiple lines with a single statement


4

5 int main()

6 {

7 cout << "Welcome\nto\n\nC++!\n";

8


10 }

Welcome

to

C++!

Multiple lines can be printed with one

statement.

C++Another Program: Adding Two Integers

IT 3rd Sem

>> (stream extraction operator)When used with cin, waits for the user to input a value and stores the value in the variable to the right of the operator

The user types a value, then presses the Enter (Return) key to send the data to the computer

Example:int myVariable;

cin >> myVariable;

Waits for user input, then stores input in myVariable

= (assignment operator)Assigns value to a variable

Binary operator (has two operands)

Example:sum = variable1 + variable2;

1. Load <iostream>

2. main

2.1 Initialize variables integer1, integer2,

and sum

2.2 Print "Enter first integer"

2.2.1 Get input

2.3 Print "Enter second integer"

2.3.1 Get input

2.4 Add variables and put result into sum

2.5 Print "Sum is"

2.5.1 Output sum

2.6 exit (return 0)

Program Output

1 // Fig. 1.6: fig01_06.cpp

2 // Addition program


4

5 int main()

6 {

7 int integer1, integer2, sum; // declaration

8

9 cout << "Enter first integer\n"; // prompt

10 cin >> integer1; // read an integer

11 cout << "Enter second integer\n"; // prompt

12 cin >> integer2; // read an integer

13 sum = integer1 + integer2; // assignment of sum

14 cout << "Sum is " << sum << endl; // print sum

15


17 }

Enter first integer

45

Enter second integer

72

Sum is 117Variables can be output using

cout << variableName.

endl flushes the buffer and prints a

newline.

Notice how cin is used to get user input.

C++

C++Built-in (Library) Function

IT 3rd Sem

Function Exponentiation

pow (x, y) x is raised to power y; (xy )

sqrt (x) Square-root of x

sin (x) Sine of x

cos (x) Cosine of x

tan (x) Tangent of x

exp (x) Exponentiation of x, ( ex)

fabs (x) Absolute Value of x, | x |

log (x) Logarithm of x (base e)

log10 (x) Logarithm of x (base 10)

floor (x) Rounding-down x

ceil (x) Rounding-up x

______etc. {there are more}_______________________

Eg.1. floor (9.2) = 9.0

Eg.2. floor (-9.8) = -10.0

Remark:you need to include <math.h> to be able to use these functions. In newer versions it is #include<cmath>

C++Common programming Errors

IT 3rd Sem

Divide by zero.

Not including iostream for input/output operations.

Forgetting the (;) at end of each statement.

If a space found between the pair-of-symbols forthe relational operators. (i.e., > = instead of >= ).

Confusing the equality == with the assignment =.

Reversing the order of the relational operators

(i.e., => instead of >=).

C++Formatted Output

IT 3rd Sem

setw can be used to specify the width of the field that the next value of output will be printed in. To use it, you must include <iomanip.h> header file.

eg1:-

int num=12;

cout<< setw(4) << num; //num will be printed in a field width of 4 character.

eg2:-

int n1=12;

int n2=197;

cout<<setw(5)<< n1 << setw(6) << n2;

eg3:- (if the value is more than the specified setw value the compiler ignores the

setw effect and print it with the minimum number of positions required.)

int num=1977;

cout<<setw(3)<<num;

basics of c and c++ by eteaching

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