Preprocessor Directive in C++ Programming

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Preprocessor directives are lines included in the code of programs preceded by a hash sign ( # ). The preprocessors are the directives, which give instructions to the compiler to preprocess the information before actual compilation starts. Preprocessing directives are lines in your program that start with # . The # is followed by an identifier that is the directive name. The Whitespace is also allowed before and after the #.

• The first two lines define constants using the #define preprocessor directive. The constant PI is set to 3.14, and rectangle() is defined using the length and breadth parameters.
• The createString() macro uses the # operator to convert the argument to a string literal.
• The concat() macro uses the ## operator to concatenate two arguments and form a single token.
• The program then prints the area of a circle using the constant PI, the area of a rectangle using the rectangle() macro, and the new string generated by the createString() macro.
• The program also prints the value of concat(a,b) which is formed by concatenating the two characters 'a' and 'b'. Additionally, it prints out some special predefined macros such as __LINE__, __FILE__, __DATE__, __TIME__, and __cplusplus__.

Source Code

#include <iostream>
#define PI 3.14
#define rectangle(length, breadth) (length * breadth)
#define createString(s) #s
#define concat(a, b) a ## b
using namespace std;
//Preprocessor Directive in C++ Programming
int main()
{
    cout<<"Area of a circle : "<<PI*5*5<<endl;
    int length = 20, breadth = 5, area;
    area=rectangle(length,breadth);
    cout << "Area of a rectangle is: " << area<<endl;
    cout<<"New String : "<<createString(Tutor Joes)<<endl;
    int ab=100;
    cout<<"The Value of AB : "<<concat(a,b)<<endl;
    cout<<"__LINE__ :" << __LINE__ << endl;
    cout<<"__FILE__ :" << __FILE__ << endl;
    cout<<"__DATE__ :" << __DATE__ << endl;
    cout<<"__TIME__ :" << __TIME__ << endl;
    cout<<"__cplusplus:"<<__cplusplus<<endl;
 
    return 0;
 
}
 

Output

Area of a circle : 78.5
Area of a rectangle is: 100
New String : Tutor Joes
The Value of AB : 100
__LINE__ :17
__FILE__ :C:\Users\Tutor Joes\Desktop\Sandhiya\sample.cpp
__DATE__ :Mar 18 2022
__TIME__ :16:21:54
__cplusplus:201402

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Program List

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• C++ Introduction
• Hello World In C++
• Why we using namespace std in C++
• Getting Inputs in C++
• std::string class in C++
• if Statement in C++
• if else Statement in C++
• else if Statement in C++
• Nested if Statement in C++
• Switch Statement in C++
• Group Switch Statement in C++
• Salary Calculation using IF Statement in C++
• Insurance Eligibility Status using C++
• Library Fine Calculation using C++
• While Loop in C++
• do While Loop in C++
• For Loop in C++
• For Each Loop in C++
• Sum of N Numbers in C++
• Factors of a Given Number using C++
• Armstrong Number using C++
• Prime Number using C++
• Arrays in C++
• Search an Element in an array in C++
• Sum of Elements in an array in C++
• Greatest Elements in an array in C++
• Sort Elements in an array in C++
• Function In C++
• Function Overloading In C++
• Default Argument Function In C++
• Template In C++
• Enum In C++
• Class in C++
• What is Public Access Specifier in C++
• What is Private Access Specifier in C++
• Scope Resolution :: Operator in C++
• Default Constructor in C++
• Parametrized Constructor in C++
• Copy Constructor in C++
• Constructor Overloading in C++
• Destructor Overloading in C++
• Single Inheritance in C++
• Multiple Inheritance in C++
• Multilevel Inheritance in C++
• Hybrid Inheritance in C++
• Hierarchical Inheritance in C++
• Diamond Problem in C++
• Diamond Problem using Constructor in C++
• Bank Management System using Class & inheritance in C++
• What is Protected Access Specifier in C++
• Function Overriding in C++
• Operator Overloading in C++
• Unary Operator Overloading in C++
• Base Class Pointer derived Class Object in C++
• Virtual Function in C++
• Sample Virtual Function in C++
• Pure Virtual Function & Abstract Class in C++
• What is Abstraction in C++
• Getter & Setter , this Keyword in C++
• Static variables and Static Function in C++
• Friend Function in C++
• Friend Class in C++
• Change Private Values Using Friend Class in C++
• Single Value Member Initializer List in C++
• Multiple Value Member Initializer List in C++
• Add value to Base Class Constructor Using Member Initializer List in C++
• Initialized Const variable using Member Initializer List in C++
• Constructor’s parameter name is same as data member using Member Initializer List in C++
• Narrowing conversion Problem in Member Initializer in C++
• inline Function in C++
• Lambda Expressions/Functions in C++
• Preprocessor Directive in C++
• Character Classification Functions in C++
• rand() in C++
• Exception Handling in C++
• Write a File using C++ fstream
• Read a File using C++ fstream
• STL-Array in C++
• STL-Vector in C++
• STL-deque in C++
• STL-List in C++
• STL-Stack in C++

Flow Control

• Hello World
• Input From User in C++
• Arithmetic Operators in C++
• Assignment Operators in C++
• Comparison Operators in C++
• Logical Operators in C++
• Math Functions in C++

IF Statement Examples

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• If Statement in C++
• If-Else Statement in C++
• If-Else-If Statement in C++

Switch Case

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• Basic Switch Case Example
• Calculator using Switch Case
• Present Elevator Position in C++
• Hotel Management in C++
• Display Month in C++
• Find Vowels in C++
• Find Weekend in C++
• Find Weekdays in C++

Goto Statement

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• Factorial using Goto in C++
• Printing Even Numbers using Goto
• Printing Given Word using Goto
• Printing Numbers using Goto
• Printing Odd Numbers using Goto
• Sum of Numbers using Goto
• Print Tables using Goto
• Print Reverse Tables using Goto

Break and Continue

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• Printing Numbers in C++
• Printing Continues Numbers in C++

While Loop

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• Armstrong Number using While Loop
• Decimal to Binary in C++
• Printing Even & Odd Numbers
• Printing Positive & Negative Numbers
• Prime between two Numbers
• Find Prime or Composite
• Printing Numbers in C++
• Tables using While Loop
• Reverse Tables using While Loop

Do While Loop

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• Printing Array using Do While Loop
• Printing given Word
• Printing Numbers using Do While Loop

For Loop

---

• Sum of Numbers using For Loop
• Sum of Two Square using For Loop
• Alphabet Diamond Pattern
• Armstrong number using For Loop
• Cubic Numbers using For Loop
• Divisible by 7 using For Loop
• Fibonacci series using For Loop
• Formula Examples using For Loop
• Reverse Number Pattern
• Number Patterns using For Loop
• Odd & Even Numbers using For Loop
• Printing Star Diamond Pattern in C++
• Printing Flag Pattern in C++
• Printing Pyramid Pattern in C++
• Printing Boat Pattern in C++
• Diamond Pattern Outline in C++
• Square Pattern Outline in C++
• Triangle Pattern Outline in C++
• Printing Tables using For Loop
• Reverse table using For Loop
• Sum of Even & Odd using For Loop
• Squaring Numbers using For Loop
• Reverse Printing Number using in C++
• Prime or Composite using For Loop
• Common Patten Examples in C++

Friend Function in C++

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• Basic Friend Function Example
• Addition using Friend Function
• Character Integer using Friend Function
• Find Distance using Friend Function
• Length of Box using Friend Function
• Private & Protected Example in C++

String Examples

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• Basic Example of String in C++
• Addition using String
• String Append in C++
• String Capacity Function in C++
• String Character Change in C++
• String Concatenation in C++
• String Input Getline in C++
• String Length in C++
• String Palindrome in C++
• Remove Duplicate String in C++
• String Resize in C++
• String Reverse without using Function
• Sentence Case Example using String
• Swapping String in C++

Array Examples

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• Display Marks using Array
• Find Largest Number using Array
• Find Second Largest Number using Array
• Find Second Smallest Number using Array
• Find Smallest Number using Array
• Print Values using Array
• Print Array Values using While Loop
• Sum of Array Average using Array
• Transpose Matrix using Array
• Two Dimensional Array Addition
• Array Addition using Class Function
• Two Dimensional Array Subtraction
• Three Dimensional Array Example

Structure Examples

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• Area of Rectangle using Structure
• Book Information using Structure
• Person Information using Structure
• Student Information using Structure

Structure & Pointer Examples

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• Basic Example of Structure & Pointer
• Show Book Details in C++
• Find Length in C++

Structure & Functions Examples

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• Area of Rectangle in C++
• Show Book Information in C++
• Show Person Information in C++

Enumeration Examples

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• Direction Example in C++
• Week Days Example in C++

Template Examples

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• Addition using Template
• Data Types Example using Template

Functions

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• Hello World using Function
• Call by Value & Reference in C++
• Function Overloading in C++
• Function Parameter Examples in C++
• Function Recursion Example in C++
• Arithmetic Operators using Function in C++
• Sum of two Numbers in C++
• Difference between two Numbers in C++
• Division of two Numbers in C++
• Product of two Numbers in C++
• Check Prime Number using Function
• Tables using Function in C++
• Update Function in C++
• Display Marksheet using Function in C++
• Function with Argument Examples in C++

Inheritance Examples

Hierarchical Inheritance

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• Basic Example of Hierarchical
• Area of Rectangle Example

Hybrid Inheritance

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• Multiplication using Hybrid Inheritance

Multilevel Inheritance

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• Basic Example of Multilevel Inheritance
• Eat Sleep Code Example

Multiple Inheritance

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• Basic Example of Multiple Inheritance
• Addition using Multiple Inheritance

Single Level Inheritance

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• Basic Example of Single Level Inheritance
• Eating Coding Program
• Print Salary Bonus Example in C++
• Multiplication using Single Level Inheritance

Class and Objects

• Find Box Volume using Objects
• Class and Object Example in C++
• Object Creation Example in C++
• Basic Example of Multiple Objects

Constructor Example

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• Area of Rectangle using Constructor
• Constructor Overloading Example
• Constructor Invoking Example
• Constructor Deep Copy Example
• Copy Constructor Basic Example
• Copy Constructor Shallow Copy
• Parameterized Constructor Example

Destructor Example

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• Destructor Example in C++

Operator Overloading Example

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• Assignment Operator Overloading Example
• Binary Operator Example
• Increment & Decrement Example
• Input & Output Example
• Relational Operator Distance Example
• Operator Overloading Example
• Distance Measuring using Unary Operator

Operator and Function Example

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• Display Values using Friend Function

List of Programs

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• Classes Example in C++
• Pointer to Classes in C++
• Data Hiding in C++
• Constructor Example in C++
• Copy Constructor in C++
• Scope Example in C++
• Inline Function in C++
• Struct vs Class in C++
• Operator Overloading in C++
• Friend Function in C++
• Insertion Overload in C++
• Inheritance Example in C++
• Single Inheritance in C++
• Access Specifier in C++
• Function Overriding in C++
• Runtime Polymorphism in C++
• Abstract Class in C++
• Friend Class in C++
• Static Member in C++
• Static Member Function in C++
• Nested or InnerClass in C++
• Dynamic Heap in C++
• Try Catch in C++
• Try Catch Function in C++
• More About Catch in C++
• Template in C++
• Template Class in C++

Pointer Examples

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• Basic Example of Pointer in C++
• This Pointer Example in C++
• Null Pointer Example in C++

Memory Management Examples

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• Dynamic Memory Allocation Example
• Creation & Deletion Array Example

Pointers and Arrays

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• Basic Example of Pointer & Array
• Print Character using Pointer & Array
• Print Floating Values Example in C++
• Print Array Values Example in C++

Virtual Function Examples

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• Basic Example of Virtual Function
• Load Features Example in C++

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