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Variables types in C++ programming

A variable is a storage area that is used to store data. The variable contains data that can be changed at any time during program execution.

Variable This is the name of a memory location. Variable is an identifier is used to represent a particular type of information in a part of a program. We can see a Variable as a container is used to store a value. Variable This is the name of a memory location.

INDEX –

  1. Variables in c++ programming
  2. rules of declaring variables in c++ programming
  3. Variable Declaration
  4. Definition
  5. Variable initialization
  6. Types of variable
  7. Global variable
  8. Local variable
  9. Conclusion
  10. Frequently asked questions

Variables in c++ programming

rules of declaring variables in c++ programming

Variable is case sensitive. for eg int a and int,  A these are different variables.

A Variable starts with any alphabet (a-z, A-Z) or underscore (_).

Variables can be named alphanumeric. For eg. a1 = 5, var1, var2 For eg. a1 = 5, var1, var2

Variable does not allow space.

The Variable name is not any C ++ keywords.

After declaring a variable, it is given a value. This value is given by the equal sign (=).

Like – x = 5; Or a = 10;

Each data type has a variable

Syntax –

  • Without assigning value:- <data type> <variable name>;
  • With assigning value:- <data type> <variable name> = <variable value>;
data typeExampleDescription
int a = 2;The int data type is used to declare numeric values.
charch = ‘H’; and str[]=”hello”;We use the char data type to declare the character.
floatf = 2.3;Float data type is used to declare variables like floating-point, but they are single-precision.
doubled = 2.30;Double data type is used to declare variables like floating-point, but they are double-precision.
boolb = true; or b = (!false)There are two values ​​for bool. True and False
wchar_t str[] = L”Hello”;This is a wide character data type.
variable in c++

Datatype  Example  Description

int –   int a = 2;     The int data type is use to declare numeric values.

Char- char ch = ‘H’; and char str [ ] = “hello”; Use the char data type to declare the character.

Float – float f = 3.3; Float data type is used to declare variables like floating-point, they are single precision.

Double – double a = 3.20; Double data type is used to declare variables like floating-point, they are double precision.

Bool– holds boolean value true or false

Variable Declaration –

Variable declares, this variable allocates memory according to the data type.

After being a variable declared, it takes Garbage Value inside itself.

Garbage Value – Garbage Value Variable is given by Compiler.

ever using a variable it has to declare.

Syntax for Single Declaration

data_type single_variable_name;

Example – int a;

#include<iostream>
using namespace std;
int main(){
int a;
cout<<“Value of a : “<<a;
return 0;
}

Output –

single variable

Syntax for Multiple Variable Declaration

data_type multiple_variable_name;

Example – int a, b, c;

#include<iostream>
using namespace std;
int main(){
int a, b, c;
cout<<“Value of a : “<<a<<endl; cout<<“Value of b : “<<b<<endl; cout<<“Value of c : “<<c<<endl;
return 0;
}

Output –

Multiple Variable Declaration

Definition –

A variable definition is a part where the variable is assigned a memory location and a value. Most of the time, variable declaration and definition are done together.

Initialization –

Variable initializes, this variable allocates memory according to the data type it is. For eg. int for 2bytes (16-bit) | 4bytes (32-bit) | 8bytes (64-bit), char

In variable initialization, a variable takes only one value.

The Syntax for Single Initialization

data_type single_variable_name = value;

Example – int a = 8;

#include<iostream>
using namespace std;
int main(){
int a = 8;
cout<<“Value of a : “<<a;
return 0;
}

Output –

Single  Initialization

Syntax for Multiple Variable Initialization

data_type single_variable_name = value, single_variable_name = value;

Example – int a=5, b=6;

#include<iostream>
using namespace std;
int main(){
int a = 5, b = 6;
cout<<“Value of a : “<<a<<endl; cout<<“Value of b : “<<b;
return 0;
}

Output –

Syntax for Multiple Variable Initialization

Variable Redeclaration –

Variable cannot be redeclare.

Example –

#include<iostream>
using namespace std;
int main(){
int a, b;
int b;
cout << “Value of a : ” <<a;
return 0;
}

Output –

Variable Redeclaration

Types of variable

1. Global variable


2. Local variable

Types of variable

1. Global variable –

Global variables are those variables. we can access the entire program variables that are defined at the beginning of the program.

A global variable is a variable that declares outside of functions. The global variable can be used in all functions.

The visibility of Global Variables occurs throughout the program.

The default value of Global Variables is ‘0’

Example –

#include<iostream.h>
#include<conio.h>
 
// number is a Global variable
   int number=50;
void seo()
{
     cout<<“Your Number is : “<<number;
}
void main()
{
  clrscr();
     seo();
    getch();
}

Output –

2. Local variable –

The default value of Local Variables is ‘garbage value‘.       

The local variables are variables that are declared inside a function. These local variables can only be used within the function or block in which these are declared.

The use of such variables remains limited to block only.

for example, you have created a variable in a function, then you cannot use a variable outside function.

Example –

#include<iostream.h>
#include<conio.h>
void seo()
{
     // number is a local variable
     int number=20;
}
void main()
{
    // Error: because access to local variable
    cout<<number;
    getch();
}

Output –

In the code, int variable is declare seo(). Whose name is number.

this variable is Access in the main () function. the error will happen in the program num is a local variable. It can only use in seo ()

   Difference between Global variable and Local variable in c++

Global variableLocal variable
Global Variable is called variable which is defined at the top of the program declared outside the function.Local Variable is the variable is declared inside the function.
Global Variable can be accessed anywhere Local Variable can be accessed only inside the function in which that variable is declared.
Global variable has initial value int = 0, float = 0.000000, char- “Blank Space (Non-Printable Char)”initial value of Local variable is garbage.
The scope of  Global Variable means that its availability persists throughout the program,the scope of Local Variable means that availability remains until the function or block is executed.
The data segment of a Global variable is stored in the area which is the public area.the data of Local Variable is stored in the stack.

read also – control statements

Some special types of variable

There are some special keywords, to impart unique characteristics to the variables in the program.

Final –

Sometimes you don’t want to allow derived class to override the base class’ virtual function. C++ 11 allows a built-in facility to prevent overriding of a virtual function using the final specifier.

    final int i=1;

Static –

These variables hold their value between function calls. Static is a keyword in C++ used to give special characteristics to an element. Static elements are allocated storage only once in a program lifetime in a static storage area. And they have a scope till the program lifetime.

    static int y=2;

source –wikipedia

Conclusion –

Variable types, Variable Declaration, Variable Definition, Variable Initialization all of them Syntax, example, output I gave you above.

Friends, reading this post completely, you must have understood Variables in c++ programming. you must have liked it, I try to describe to you in simple language, maybe you must have understood it in this post. I have covered Topics you do not need to read any other post this post helped you share your friends.

Frequently Asked Questions

1. What is a variable?

A variable is a storage area is used to store data.

2. Types of variables in c++?

The variables in C ++ are tow types.
Local Variables, Global Variables

3. Does Variable allow to space?

Variable does not allow space.

4. Does each data type has a variable?

Yes, Each data type has a variable.

5. What is Garbage Value?

Garbage Value Variable is given by Compiler.

6. What is the default value of the local variables?

The default value of Local Variables is ‘garbage value’.

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