In order to evaluate a comparison between two expressions, a relational operator can be used. The result of a relational operation is a Boolean value that can only be true or false.
In C++, there are six relational operators. They include:
==!=><>=<=They are called relational because they evaluate how two expressions on either side of the operator relate to each other.
For example, the relation produces the integer value 0, meaning false.
The descriptions, as well as examples of the six relational operators, are represented in the table below. Assume variable A holds 1 and variable B holds 2, then:
Operator | Description | Example |
== | Helps check if the values of two operand are equal or not, if they are equal then condition becomes true | A == B is not true because A is not equal to B |
!= | Helps check if the values of two operands are equal or not, if the values are not equal then condition becomes true | A != B is true because A and B are not equal |
> | Helps check if the value of left operand is greater than the value of right operand, if A is greater than B, then condition becomes true | A > B is not true because A is not greater than B |
< | Helps check if the value of left operand is less than the value of right operand, if A is less than B, then the condition becomes true | A < B is true because A is less than B |
>= | Helps check if the value of left operand is greater than or equal to the value of right operand, if the value of A is either greater or equal to the value of B, then the condition becomes true | A >= B is not true because A is neither greater nor equal to B |
<= | Helps check if the value of left operand is less than or equal to the value of right operand, if A is either less or equal to B, then the condition becomes true | A <= B is true because A is at least greater than B |
Now, let’s see a very simple example using the relational operator greater than >.
#include <iostream>using namespace std;int main() {int x,y;cout<<"Enter two integers:";cin>>x>>y;if(x>y)cout<<x<<endl;else cout<<y<<endl;return 0;}
Enter two integers: 10, 20
20
In the program above, the condition given is (x>y). If x is greater than y, the condition is true and evaluates to 1; otherwise, the condition is false and evaluates to 0. So, x is printed precisely when it is greater than y.
Below, the example includes all relational operators in the example below.
In the code below, and .
#include <iostream>using namespace std;int main(){int a=2;int b=1;if(a==b){cout << "Line 1: a is equal to b"<<endl;}else{cout << "Line 1: a is not equal to b"<<endl;}if(a<b){cout << "Line 2: a is less than b"<<endl;}else{cout << "Line 2: a is not less than b"<<endl;}if(a>b){cout << "Line 3: a is greater than b"<<endl;}else{cout << "Line 3: a is not greater than b"<<endl;}/* lets change the values of a and b */a=5;b=20;if(a<=b){cout << "Line 4: a is either less than or equal to b"<<endl;}if(b>=a){cout << "Line 5: a is not greater than or equal to b"<<endl;}return 0;}