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++ Auto keyword in C++ C++ 11 vs C++ 14 vs C++ 17 C++ STL (Standard Template Library) Differences Between C Structures and C++ Structures Divide by Zero Exception in C++ Dynamic Constructor in C++ Dynamic Memory Allocation in C++ Find the Size of Array in C/C++ without using sizeof() function Floating Point Operations and Associativity in C, C++ and Java Hello World Program in C++ How to create a table in C++ How to Setup Environment for C++ Programming on Mac Implementation of a Falling Matrix in C++ Message Passing in C++ Pointer to Object in C++ Templates in C++ vs Generics in Java Ways to Copy a Vector in C++ What does Buffer Flush mean in C++ sort() function in C++ Structure Sorting (By Multiple Rules) in C++ Similarities between C++ and Java std::distance in C++ Array program in C++ C++ Tricks for Competitive Programming Desired Capabilities in Selenium Web Driver in C++ Socket Programming in C++ Template Specialization in C++ Classes and Objects in C++ Convex hull Algorithm in C++ DES in C++ C++ vardiac() function Difference between Two Sets in C++ Difference between Exit and Return Structured Binding in C++ Differences between Local and Global Variable Bitwise Operator vs Logical Operator Difference between OOP and POP in C++ Fork in C++ Functors in C++ How to call a void function in C++ How to create a directory or folder in C/C++ How to create a library in C++ How to create a stack in C++ How to create the Processes with Fork in C++ How to Handle Divide by Zero Exception in C++ Lambda Expression in C++ Pattern programs in C++ Roadmap to C++ Programming Substring in C++ Virtual base class in C++ Bits stdc++.h in C++ Top 14 Best Free C++ IDE (Editor & Compiler) for Windows in 2022 Bitmasking in C++ Auto Keyword in C++ Features of OOPS in C++ Hospital Management Project in C++ How to Declare Unordered Sets in C++ How to Sort an Array in C++ Include Guards in C++ Iostream in C++ Method overriding in C++ How to run program in turbo c++ How to Use Getline in C++ Leap Year Program in C++ Naming Convention in C++ New Operator in C++ Nullptr in C++ Object Slicing in C++ Principles of Object-Oriented Programming in C++ Processing strings using std string stream in C++ Pure Virtual Function in C++ With Example Program Random Number Generator in C++ Singleton Design Pattern in C++ Size_t Data Type in C++ Skyline Problem in C++ System() function in C++ Web Development in C++ Data Hiding in C++ Difference between exit() and _Exit() in C++ Hashing in C++ Object in C++ Sum of all Elements between k1’th and k2’th Smallest Elements Virtual class in C++ Vector Size in C++ Top best IDEs for C/C++ Developers in 2022 Tensorflow in C++ Sliding Window Technique in C++ Reverse String Word-Wise in C++ Returning a Function Pointer from a Function in C/C++ RTTI in C++ Pthreads or POSIX Threads in C++ Reserved Keywords in C++ Passing a Vector to a function in C++ 10 Best C and C++ Books for Beginners & Advanced Programmers Add two numbers represented by two arrays in C++ Array of Object in C++ C++ Program For FCFS Containership in C++ Counting Frequencies of Array Elements in C++ Decltype type Specifier in C++ Dynamic _Cast in C++ Difference between int main() and int main(void) in C/C++ Depth First Search Program to Traverse a Graph in C++ Features and Use Of Pointers in C/C++ Fread Function in C++ Programming Fscanf Function in The C++ Functions in C++ With Types and Examples Gmtime Function in C/C++ How is Multiset Implemented in C++ How to Build a Program in C++ How to Declare a 2d Array Dynamically in C++ inheritance Program in C++ int Max and int Min in C/C++ is It Fine to Write Void Main Or Main in C/C++ How to create a button in C++ abs() function in C++ Compile Time Polymorphism in C++ Division in C++ Factorial of a Number in C++ using while Loop Multiset in C++ 4 Pillars of OOPs Approach in C++ Backtracking Time Complexity in C++ C++ Global Variable C++ Pipe Tutorial Observer Design Pattern in C++ Private Inheritance in C++ Pthread in C++ Parameters SDL library in C++ with Examples Pointers in C++ Abstract Factory Design Pattern in C++ Ascending order in C++ How the value is passed in C++ Call by Pointer in C++ Constexpr in C++ Deadlock in C++ Design Patterns in C++ Factory Method for Designing Pattern in C++ How to calculate size of string in C++ Name Mangling and extern in C++ Preventing Object Copy in C++ Program that produces different results in C and C++ Quick Sort in C++ Single Handling in C++ Type difference of Character literals in C VS C++ Use of Inheritance in C++ User-defined literals in C++ Vector methods in C++ Void * in C and C++ Zombie and Orphan Process in C++ Isprint() in C++ List and Vector in C++ List iterators in C++ Merging Two Vectors in C++ Sleep function in C++ Stoi function in C++ String erase() in C++ String Trim in C++ When should we write own Assignment operator in C++ C++ tcp client server example C++ tcp server example Early Binding and Late Binding in C++ Factory Design Pattern in C++ Fisher-Yates shuffle algorithm in C++ For Auto in C++ Group anagrams in C++ How to convert binary string to int in C++ How to convert string to float in C++ How to remove space from string in C++ How to use pair in C++ How to use the string find() in C++ Dynamic Casting in C++ 2D Vector Initialization in C++ C++ GUI Visual Studio C++ IPC C++ Macro Function Example C++ Permutation Overloading Stream Insertion in C++ Overloading array Index operator in C++ Operators that cannot be overloaded in C++ Operator overloading in C++ isprint() function in c++ Is_trivial function in C++ Is assignment operator Inherited in C++ div() function in C++ Default Assignment Operator and References in C++ Copy Constructor vs Assignment Operator in C++ Conversion Operator in C++ Array sum in C++ STL C++ Define Macro C++ Design C++ Factory Pattern TCP Client Server Example in C++ Convert String to Uppercase in C++ exit() and _Exit() in C and C++ Initializer list in C++ Iterator invalidation in C++ Lower bound in C++ Modulus of Two float numbers or double number Pass by value in C++ Set insert function in C++ Std partition_point in C++ Unary Operator Overloading in C++ Using Default Arguments with Virtual Functions Virtual Functions and Runtime Polymorphism What is endl in C++ What is Unary Operator Overloading in C++ Which operators cannot be overloaded in C++ C++ Program to Divide the String Into N equal Parts Gray Code to Binary Code in C++ How to get the value of pi in C++ Multimap value_comp() function in C++ Vector of Vectors in C++ Naïve Bayes Algorithm in C++ Minimum Cost Path Problem in C++ 10 C++ Programming Tricks You Should Know btowc() function in C++ forward_list::cend() in C++ Unordered_multimap max_load_factor() function in C++ Cpp_int in c++ Dynamic Objects in C++ FLOCK() FUNCTION IN C++ Generate Random Double Numbers in C++ How to Assign Infinity to a Number in C++ Jump statements in C++ Multipath inheritance in C++ Out of Range Exception in C++ Size of Class in C++ Size of string in C++ std::binary_negate in c++ Thread_local in C++ Tokenizing a String in C++ Ancestors of a Node in Binary Search Tree C++ program for Double to String Conversion C++ Program to Demonstrate Use of Formatting Flags on Float Output Clamp in C++ K-Dimensional Tree in C++ Mutable Lambda in C++ Power Set in C++ Program to Find Sum of Geometric Progression Std::Back_inserter in C++ Strpbrk() function in C++ Size of int in C++ TYPES OF MANIPULATORS IN C++ Double colon in C++ How to sort vector in C++ How to use Setprecision in C++ How to write a Vector in C++ Insertion in Splay Tree in C++ Merge Sort Algorithm in C++ Printing a Character using ASCII value in C++ Regex in C++ Size of Data Types in C++ Abstract Factory Design Pattern in C++

C++ Global Variable

In C++, a global variable is a variable that is defined outside of any function or class and can be accessed by any function or class in the program. Global variables are typically defined at the top of a source file before any functions or classes are defined. They are often used to store data that needs to be shared across multiple functions or classes. However, the use of global variables can lead to code that is difficult to maintain and debug, as it can be unclear where a particular variable is being modified. Additionally, global variables can also lead to naming conflicts if two or more variables have the same name.

C++ Global Variable

Use of Global Variable

The use of global variables can lead to a number of problems, However, one of the main issues with global variables is that they can make code difficult to maintain and debug. Because global variables can be accessed and modified from anywhere in the program, it can be unclear where a particular variable is being modified, and this can make it difficult to track down bugs. Additionally, global variables can also lead to naming conflicts if two or more variables have the same name.

Another issue with global variables is that they can introduce tight coupling between different parts of the program. When a global variable is used in multiple functions or classes, changes to the value of that variable can have unintended consequences in other parts of the program. This can make it difficult to make changes to the program without breaking other parts of the code.

In general, it is considered best practice to minimize the use of global variables and to use them only when necessary. Instead of using global variables, it is often better to pass data as function arguments or to use class variables and methods to encapsulate data and behavior. Additionally, it can also be useful to use the "const" keyword to define read-only global variables, to prevent the value of the variable from being accidentally modified.

In conclusion, while global variables can be useful in certain situations, they should be used with caution. The use of global variables can lead to code that is difficult to maintain and debug and can introduce tight coupling between different parts of the program. It is generally considered best practice to minimize the use of global variables, and to use them only when necessary. Instead of using global variables, it is often better to pass data as function arguments or to use class variables and methods to encapsulate data and behavior.

Example of C++ global variable

Here is an example of a global variable in C++:

#include <iostream>


// Global variable
int g_counter = 0; // Initial value is 0


void incrementCounter()
{
    g_counter++;
}


int main()
{
    std::cout << "Counter: " << g_counter << std::endl; // Outputs "Counter: 0"
    incrementCounter();
    std::cout << "Counter: " << g_counter << std::endl; // Outputs "Counter: 1"
    return 0;
}

Output:

Counter: 0
Counter: 1

In this example, the variable "g_counter" is a global variable that is defined at the top of the file, before any functions or classes. The variable is assigned an initial value of 0. The function "incrementCounter" increments the value of the global variable by 1. The main function then prints the value of the global variable to the console. As the global variable is accessible to all functions, the main function can access and modify the value of the global variable.

Also, it is important to note that the use of global variables may lead to naming conflicts, and tight coupling between different parts of the program and can make code difficult to maintain and debug.

Scope of C++ Global Variable

The scope of a global variable in C++ is the entire program. This means that a global variable can be accessed and modified from any function or class in the program, regardless of where it is defined. Global variables are typically defined at the top of a source file before any functions or classes are defined, but they can also be defined in a header file and included in multiple source files.

It is worth noting that global variables are also global to all compilation units (i.e files) if they are defined in the header files, so it is important to be mindful of the scope in which global variables are defined. If a global variable is defined in a header file and included in multiple source files, it will be accessible from all of those source files, creating a global variable that can be accessed and modified from multiple compilation units.

It is also worth noting that global variables can also be accessed and modified by other source files that are linked to the program. This means that if a global variable is defined in one source file and then another source file is linked to the program that also defines a global variable with the same name, the two variables will refer to the same memory location.