Question

Explain the scope of variables with examples.

Answer 1

Scope refers to the accessibility of a variable.
There are four types of scopes in C++

1. Local Scope
2. Function Scope
3. File Scope
4. Class Scope

1. Local Scope:

• A local variable is defined within a block. A block of code begins and ends with curly braces {}.
• The scope of a local variable is the block in which it is defined.
• A local variable cannot be accessed from outside the block of its declaration.
• A local variable is created upon entry into its block and destroyed upon exit;

Example:
int main( )
{
int a,b; //Local variable
}

2. Function Scope:

• The scope of a variable within a function is extended to the function block and all sub-blocks therein.
• The lifetime of a function scope variable is the lifetime of the function block.

Example:
int. sum(int x, int y); //x and y has function scope.

3. File Scope:

• A variable declared above all blocks and functions (including main()) has the scope of a file.
• The lifetime of a file scope variable is the lifetime of a program.
• The file scope variable is also called a global variable.

Example:
#include
using namespace std;
int x,y; //x and y are global variable
void main()
{
……..
}

4. Class Scope:

• Data members declared in a class have the class scope.
• Data members declared in a class can be accessed by all member functions of the class.

Example:
Class example
{
int x,y; //x and y can be accessed by print() and void():
void print();
Void total();
};

Class Scope:

A class is a new way of creating and implementing a user-defined data type. Classes provide a method for packing together data of different types.
Data members are the data variables that represent the features or properties of a class.

class student } private: int mark1, mark2, total; };

The class student contains mark1, mark2, and total are data variables. Its scope is within the class of students only.