Overview of c++ language

Lecture’s outline

What is C++?
Identifiers.
Constant
Semicolons & Blocks in C++
Data type
Comments
Operator
Declaration of variables
Giving value to variable
C++ statements

prepared by Taif.A.S.G

What is C++?
• Developed by Bjarne Stroustrup (in 1979 at Bell Labs)
• C++ is regarded as a middle-level language, as it comprises a
combination of both high-level and low-level language features.
• C++ is a statically typed, compiled, general purpose, case-
sensitive, free-form programming language that supports
procedural, object-oriented, and generic programming.
• C++ is a superset of C that enhancement to the C language and
originally named C with Classes but later it was renamed C++.


identifiers
They are used for naming classes
function, module, variables, object in a program.
They follow the following rules:
1) They can have alphabets , digits, and the underscore(_).
2) They must not begin with a digit.
3) Uppercase and lowercase are distinct.
4) They can be of any length.
5) It should not be a keyword.
6) White space is not allowed.


Constant
Constant is one whose value cannot be changed after it has
been initialized-any attempt to assign to field will produce a
compile-error .So, we can declare the constant by using
const field and use all uppercase letter.
Syntax of declare the constant is:
const type name=value

Example:

const int STRENGTH = 100;
const float PI = 3.14;

Semicolons & Blocks in C++:
• In C++, the semicolon is a statement terminator.
That is, each individual statement must be ended
with a semicolon. It indicates the end of one logical
entity.
• For example: following are two different
statements:
x = y;
y = y+1;

prepared by Taif.A.S.G 6

Data type


Comments
C++ can use both the single line comments and multi-line
comments .
single line comments begin with // and end at the end of line.
For longer comments we can create multi-line comments by
starting with /* and ending with */


Operator
* / % + - are the mathematical operators
* / % have a higher precedence than + or – mathematical
operators
++ Increment operator –– Decrement operator
== Equal (careful)
!= Not equal
>= Greater than or equal Relational
<= Less than or equal operators
> Greater than
< Less than
&& logical (sequential) and
Logical
|| logical (sequential) or operators
= assignment

Declaration of variables

The general form of declaration of variables:

Type variable1, variable2,...., variableN;
Example:

int count;
float x,y;
double pi;
char c1,c2,c3;
byte b;

Giving value to variable

The general form of giving value to variables:

variableName= value;
Example:

finalValue=100;
x=y=z=0;
Yes = ‘x’;


Simple programs
 Write C++ Program to find Sum and Average of two
numbers?

Write C++ Program to find area of a circle?


C++ statement
Control
statement
Selection iteration jump
statement statement statement

If if-else switch for while do break continue return


Decision making
• C++ supports the following statements Known
as control or decision making statements.
1. if statement.
2. switch statement.
3. Conditional operator ? : statement.


Decision making with if
statement
The general form of simple if statement is :
if (<conditional expression>)
<statement action>

Example:

if (a > b)
cout<<"a > b";


statement cont..
The general form of simple if else statement is :
<statement action>
else
Example: <statement action>

if (a > b)
cout<<" a > b";
else
cout<<"a<b";


statement cont..
The general form of Multiple if else statement is :
<statement action>
else if (<conditional expression>)
<statement action>
else
Example: <statement action>
if (a > b)
cout<<" a > b";
else if (a< b)
cout<<"b > a";
else
cout<<" a=b";

Decision making with switch
statement
• The if statement allows you to select one of
two sections of code to execute based on a
boolean value (only two possible values). The
switch statement allows you to choose from
many statements.


Decision making with switch
statement cont..
switch (expr) {
case c1:
statements // do these if expr == c1
break;
case c2:
statements // do these if expr == c2
break;
case c3:
case c4: // Cases can simply fall thru.
statements // do these if expr == any of c's
break; . . .
default: // OPTIONAL
statements // do these if expr != any above
}


The ? : Operator:
• can be used to replace if...else statements. It has
the following general form:
Exp1 ? Exp2 : Exp3;
Where Exp1, Exp2, and Exp3 are expressions.
• The value of a ? expression is determined like
this: Exp1 is condition evaluated. If it is true, then
Exp2 is evaluated and becomes the value of the
entire ? expression. If Exp1 is false, then Exp3 is
evaluated and its value becomes the value of the
expression.

Simple programs
 Write C++ Program to find Number is Positive or
Negative?

Write C++ Program to find the Grade of student ?

 Write C++ Program to check the day of week by using
SWITCH-CASE?


Looping
The C++ language provides three constructs for
performing loop operations, there are:
1. The for statement.
2. The while statement.
3. The do statement.


Looping cont..
The general form of for statement:

for (initialization; test condition; increment)
{
Body of loop
}

Example:
for( x=0; x<=10; x++)
{
cout<<x;
} prepared by Taif.A.S.G 23

Looping cont..
The general form of while statement:
initialization;
while(test condition)
{
Body of loop
}

Example:
x=0;
while(x<=10)
{
cout<<x;
x++; } prepared by Taif.A.S.G 24

Looping cont..
The general form of do statement:
initialization;
do
{
Body of loop
}
while(test condition);

Example:
x=0;
do
{
cout<<x;
x++; }
while(x<=10) ; prepared by Taif.A.S.G 25

Int num2 Int num1
0 0
Nested Looping 1
for(num2 = 0; num2 <= 3; num2++) 2
{ 3 end of loop
for(num1 = 0; num1 <= 2; num1++) 1 0
{ 1
cout<<num2 << " " <<num1;
2
}
} 3 end of loop
2 0
1
2
3 end of loop
3 0
1
2
3 end of loop
4 End of loop

Functions
• A complex problem is often easier to solve by
dividing it into several smaller
parts(Modules), each of which can be solved by
itself. This is called structured programming.
• In C++ Modules Known as Functions & Classes
• main() then uses these functions to solve the
original problem.


Functions (cont..)
• C++ allows the use of both internal (user-
defined) and external functions.

• External functions (e.g., abs, ceil, rand,
sqrt, etc.) are usually grouped into specialized
libraries (e.g., iostream, stdlib, math,
etc.)


Function prototype
• The function prototype declares the input and output
parameters of the function.

• The function prototype has the following syntax:
<type> <function name>(<type list>);

• Example: A function that returns the absolute value of
an integer is: int absolute(int);
• If a function definition is placed in front of main(),
there is no need to include its function prototype.


Function Definition
• A function definition has the following syntax:
<type> <function name>(<parameter list>){
<local declarations>
<sequence of statements>
}

• For example: Definition of a function that computes the absolute
value of an integer:

int absolute(int x){
if (x >= 0) return x;
else return -x;
}

• The function definition can be placed anywhere in the program.


Function call

• A function call has the following syntax:
<function name>(<argument list>)

Example: int distance = absolute(-5);


Overview of c++ language

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Overview of c++ language