Operators and Expressions

Operators and Expressions

• Expressions are some mathematical logical units which are mainly used to perform some arithmetic calculations. Generally the expressions are used along with the operators.

•  For example: a + b is a sample expression in which the plus operator is used to perform addition of two numbers. And this addition if you want to store in the variable c then in C++ language we will write it as c = a + b.

•  Note that the assignment of the value is from right to left. Irrespective of the data types of a and b the data type of c variable will be considered for storing the final result.

What is Hierarchy of Operations?

Priority : Operators

1    :          *,/,%

2     :          ‒,+

3     :            =

• In the hierarchy of operations, based on the priority of the operators the operations are performed. And scanning of the expression will be from left to right.

For example:

20‒2+3*5/3

Step 1: Scanning from left to right we come across ‒,+ and * operators the highest priority is to * so perform 3*5 first.

Step 2: In the expression 20‒2+15/3 now the division will take place.

Step 3: In the expression 20 ‒ 2 + 5 the subtraction will be performed, since + and have the same priority the operator coming first from left side will be considered.

 Step 4: In the expression 18 +5, the evaluation will result to 23.

•  To learn the expressions it is very much necessary to get introduced with the operators.

Conditional Operator:

The conditional operator is "?". The syntax of using conditional operator is

condition?expression 1:expression2

For example:

a>b?true:false

This means if a is greater than b, if yes then the value will be true otherwise it will be false.

C++ Program

#include<iostream>

using namespace std;

void main()

{

       int a,b,c;

       a=3;

       b=7;

       cout<<"\nThe value of a= "<<a;

       cout<<"\nThe value of b= "<<b;

       cout<<"\nThe addition of a+b= "<<a+b;

       cout<<"\nThe subtraction of b‒a= "<<b‒a;

       cout<<"\nThe multiplication of a*b= "<<a*b;

       cout<<"\nUse of conditional operator...";

       c = (a>b)? a: b;

       cout << c;

}

Output

The value of a= 3

The value of b= 7

The addition of a+b= 10

The subtraction of b‒a= 4

 The multiplication of a*b= 21

 Use of conditional operator...7

1.Scope Resolution Operator

• The ::operator is used to define the scope of the variable or function. One can declare the function inside the class and can write its definition outside the class. But while doing so the programmer has to specify the belonging class name, scope operator, and name of the function. Let us understand it with the help of program.

• Let us discuss a C++ program which is making use of scope resolution operator

C++ Program

#include<iostream>

using namespace std;

int a=5;

int main()

{

       int a=15;

       {

       int a=20;

       cout<<"INNER BLOCK\n";

       cout<<"Value of a= "<<a<<endl;

       cout<<"The scope of a= "<<::a<<endl;

       {

              int a=25;

              cout<<"INNER‒INNER BLOCK\n";

              cout<<"Value of a= "<<a<<endl;

              cout<<"The scope of a= "<<::a<<endl;

       }

       }

       cout<<"OUTER BLOCK\n";

       cout<<"Value of a = "<<a<<endl;

       cout<<"The scope of a= "<<::a<<endl;

        return 0;

}

Output

INNER BLOCK

Value of a= 20

The scope of a= 5

INNER‒INNER BLOCK

Value of a= 25

The scope of a= 5

OUTER BLOCK

Value of a = 15

The scope of a= 5

Program Explanation

In above program we have redeclared a variable a whose value is modified on entering each new block. Note that a block can be defined using { and }. The scope resolution operator is used to denote the scope of the variable. The scope of the variable is always a global scope. Hence each time we get output as 5 for ::a but the value of variable a gets changed each time in the block and that corresponding value can be displayed as an output.

Review Question

1. Explain various operators that are available in C++ with neat illustrations for each of it.