Symbol of Scope Resolution Operator in C++ is : :
when using Scope Resolution Operator in C++?
- To Define function outside of the class
- To Define the value of the static variable
- Access Global variable
1) To Define function outside of the class
When You create a Class and write a function definition, and you want to declare a function outside of the class so you must use a scope resolution operator.
Syntax
Return_type Class_name : : function_name (parameter )
{
// code of function
}Example
#include<iostream>
using namespace std;
class test{
public:
int a=20, b=25, c;
void sum(void);
};
void test :: sum(){
c = a + b;
cout<<"sum of a + b = "<<c;
}
int main(){
test t1;
t1.sum();
return 0;
}Output
sum of a + b = 45
2) To Define the value of a static variable
When You define a Static variable in the class, It has a value is zero. if You want to define some value to a static variable, you can not give a value without using the scope resolution operator.
Also Read This :- Write a Program to Sum of Two Numbers in c++
Syntax
Variable_Type Class_name : : variable_name = value
Example
#include<iostream>
using namespace std;
class test{
public:
static int a;
};
int test :: a = 10;
int main(){
test t1;
cout<<"current value of a = "<<t1.a;
return 0;
}output
current value of a = 10
3) Access the Global variable
If your program has the same name as the global variable and a local variable, so global variable you can not use them directly. and you want to use a global variable, then you must require the use of scope resolution operators.
Syntax
: : variable_name.
Example
#include<iostream>
using namespace std;
int x = 10;
int main(){
int x = 30;
cout<<"Global value of a = "<<::x<<endl;
cout<<"local value of a = "<<x;
return 0;
}output
Global value of a = 10 local value of a = 30
