C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++ Returning Multiple Values from a Function using Tuple and Pair in C++ wcscpy(), wcslen(), wcscmp() Functions in C++

Differences between #define & const in C/C++

 Differences between #define & const in C/C++

A preprocessor directive is #define. The preprocessor replaces things defined by #define prior to starting compilation.

In this chapter, we'll learn about the member, variable, and macro definition of const data. Const and #define are both used in source code for handling constants, but they have few differences.

#define is a preprocessor, while const is keyword

#define is used to identify these values with a tag, this set string is known in C++ as a macro description, while const is a keyword used it to consistent the identification value.

#define does not control scope, while const is controlled scope

Macro can be used to include the relevant header file anywhere in the program or in other files; therefore macros are not constrained by scope, but the constant can be specified within the feature and can therefore only be accessible within the feature/domain where constant is listed, so we can conclude that const member is also managed by sector.

The use of const is often good for practice. Since we can monitor their distance when using const. When placed inside each user defines feature, its effects will be limited to the component, and if placed outside of these user defines operations, then all files are universal.

C++ example, demonstrating use of #define and const

#include <iostream>
using namespace std;
//macro definition
#define P 80
//global integer constantt
const int K = 25;
int main()
{
          //local ineteger constant`
          const  int T = 55;
          cout<<"Value of K:  "<<K<<endl;
          cout<<"Value of P:  "<<P<<endl;
          cout<<"Value of T:  "<<T<<endl; 
          return 0;
}

Output:

 Differences between #define & const in C/C++

K is a global symbolic constant in the above program but is pre-processed before compilation and P and also global constant, whereas T is local for the main function.

Macros (#define) can be redefined, but const cannot.

Macro (defined) can be reinvented anywhere in the system (by undefining and then defining), but constant cannot be redefined or reinvented even if we cannot reallocate the value in constant.

C++ Example, to redefine a defined Macro

#include <iostream>
using namespace std;
//macro definition
#define S 60
int main()
{
          cout<<"Value of S: "<<S<<endl;
          #undef S
          #define S 600
          cout<<"Value of S: "<<S<<endl;
          return 0;
}

Output:

 Differences between #define & const in C/C++

You can see here that we modified the value of S, and it successfully executed the program as well as changes the value.

C++ Example, to redefine (re-assign) a content - (ERROR)

#include <iostream>
using namespace std;
//constant int
const int T=30;
int main()
{
          cout<<"Value of T: "<<T<<endl;
          T=200;        //error, we can not assign value to const
          cout<<"Value of T: "<<T<<endl;
          return 0;
}

Output:

 Differences between #define & const in C/C++

You can see here that we did not affect the periodic value, rather here we've tried to change T 's value, and there's a compilation error.



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