Different Types of functions in C/C++ ?

            Function types

            There are two types of functions which are as follow:

1.      User-defined Functions

2.      Built-in Functions

User-defined function

User-defined function is a function that is defined by the user. A program may have many user-defined functions or may not have user-defined functions.

Example:

int odd(int);

 int even(int);

Built-in functions

Built-in function is a function which already exists in any programming language.

It is also called as library function.

Example:

cin>>, cout>>

How to call function in C/C++ ?

Function Call

Function call is a process of calling a function. It disturbs the normal flow of execution of a                program.

When a function is called the control moved to that function and after executing the instructions of the called function came back to main() function and execute the remaining instructions of the main().

Here is a complete example to understand the function declaration, function definition and function call.

#include<conio.h>

            #include<iostream.h>

            void display();

            coid main(){

            clrscr();

            display();

getch();

}

void display()

{

cout<< ”Hello World” ;

}

What is control structure and how many types are ?

Control structure:

Control structure defines the flow of execution of a program.

There are following control structures:

1.      Sequential

2.      Iteration

3.      Conditional

4.      Functions

           Sequential

The sequential control structure is a type which defines that the flow of execution will in a sequence.

Here is an example to understand it

#include<iostream.h>

#include<conio.h>

void main()

{

  clrscr();

  cout << “Hello world” ;

  getch();

}

The above program is the example of sequential control structure. It means that firstly clrscr(); function will be executed and then cout<< “Hello world” ; statement will be executed and then getch(); function will be executed. It is the normal flow of the execution of a program.

           Iteration

Iteration means repetition. Iteration means repeating a block of statement instead of writing the same statement many times.

Here is an example to understand:

#include<iostream.h>

#include<conio.h>

void main()

{

            clrscr();

            int c=0;

            while(c<=5)

                        cout << “I love Pakistan” << endl ;

            getch();

}

            Output:

                        I love Pakistan

I love Pakistan

I love Pakistan

I love Pakistan

I love Pakistan

The above example is the example of iteration control structure. It will execute until value of c doesn’t reached to 5. Means it repeats cout << “I Love Pakistan” << endl ; five times.

The above output can be generated by the following program.

#include<iostream.h>

#include<conio.h>

void main()

{

  clrscr();

  cout << “I love Pakistan” << endl ;

  cout << “I love Pakistan” << endl ;

  cout << “I love Pakistan” << endl ;

  cout << “I love Pakistan” << endl ;

  cout << “I love Pakistan” << endl ;

  getch();

}

            There are the main types of loops:

1.      while loop

2.      do-while loop

3.      for loop

Later we will discuss about the types of loop in details.

            Conditional

Conditional control structure defines the flow of execution of a program in a condition.

Here is an example to understand the conditional control structure.

#include<iostream.h>

#include<conio.h>

void main()

{

  clrscr();

  int marks;

  cout<< “Enter marks: ” ;

  cin>> marks;

  if (marks > 40)

       cout<< “ Congratulation! You have passed ” ;

  getch();

}

In the above example if you input marks to 40 the output will be “Congratulation! You have passed” otherwise there will be nothing in the output of the program.

           Function:

A Function is a set of instructions which is used to perform a specific task. Every C++ program has at least one function which is main(). You can divide your program info different function depending on you.

Example:

A simple example of the function is the “clrscr();” function which is used to clear the output window.

What are operators in C++ and types of operators ?

Operators:

Operators are symbols which are used to perform arithmetic, conditional and logical operations or manipulations.

There are the following operators in C++:

1.      Arithmetic operators

2.      Comparison operators

3.      Logical operators

4.      Other operators

1.     Arithmetic operators:

Arithmetic operators are used to performing arithmetic operations such as addition, subtraction, multiplication and division.

Operator Name	Description	Operation
+	Used to add operands.	2 + 3 = 5
-	Used to subtract operands.	4 - 2 = 2
*	Used to find product of operands.	7 * 3 = 21
/	Used to perform division.	12 / 4 = 3
%	Provide the reminder of the division.	12 / 4 = 0

2.     Comparison operators:

Comparison operators compare two values or operands to check whether it is greater, less or equal.

Operator name	Description	Operation
<	Used to find the smaller value	IF( A < B ) then  TRUE
>	Used to find the greater value	IF( A > B) then TRUE
<=	Used to find less than or equal value	IF(A <= B) then TRUE
>=	Used to find greater than or equal value	IF( A >= B ) then TRUE
!=	Used to find not equal value	IF (A != B) then TRUE
==	Used to find equal value	IF ( A == B) then TRUE

3.     Logical Operators:

Logical operators are used to apply logical functions which are:

1. AND ( && )
2. OR ( || )
3.  NOT ( ! )

AND:

AND Operator works with at least two operands:

X	Y	X AND Y
0	0	0
1	0	0
0	1	0
1	1	1

It evaluates the result of two conditions if the both conditions are true otherwise false.

Here is an example to understand it:

If ((A > B) && (A > C))

            cout << A << ” is greater ”;

In the above example if the value of A is greater than B and greater than C the result will be A.

OR:

OR operator is also a logical operator which evaluates the result if one of them conditions is true

X	Y	X OR Y
0	0	0
1	0	1
0	1	1
1	1	1

Here is an example to understand it:

If ((A > B ) || ( A < C))

            cout << A << ” is greater ”;

In the above example the result will be value of “A” if A is greater than B or C.

NOT

NOT operator is the negation of the result it shows the result true if condition is false and wise versa.

X	!(X)
0	1
1	0
0	1
1	0

Here is an example to understand it:

If ( !( A > B ) )

            cout << B << ” is greater ”;

In the above example if the value of A is greater than B the NOT operator will change the result and shows that B is greater than A.

4.     Other Operators:

These are the some other operators which are also used:

·         Assignment operator

·         Compound assignment operator

·         Increment/decrement

·         Ternary operator “?”

Assignment operator:

      Assignment operator is used to assign a value to a variable.

      Int A=10;

Compound assignment operator:

Compound assignment operators are used to assign value as well as operation with value.

A+=10 à  A = A + 10;

      Increment/decrement

Increment operator increases the value of a variable by 1 and decrement decreases the value of the operator by 1

A=10;

B = ++A;	Here the value of B is 11 because firstly it is incremented by 1 and then assigned to B.
C = --A;	Here the value of C is 9 because firstly it is decremented by 1 and then assigned to C.
X = A--;	Here the value of X is 10 because firstly the value of A is assigned to X and then    decremented by 1.
Y= A++;	Here the value of Y is 10 because firstly the value of A is assigned to Y and then incremented by 1.

       Ternary operator

The ternary operator is used to evaluating a condition. It returns one value of result depends on the condition.

Condition ? “result1” : “result2” ;

If the condition is true the output will result1 otherwise result2.

Example:

A = ( 7 > 2 ) “True” : “False” ;

The value of A is true because the condition is true and output is “True”.