We have discussed Introduction to Operators in C where we got an overall idea of what types of Operators, C and C++ support, and its basic implementations. Following that, we studied Arithmetic Operators where we got a detailed understanding of the types and use of Arithmetic operators in C and C++. In this article, let’s try to understand the types and uses of Relational and Logical Operators.
Relational Operators
Relational operators are used for the comparison of two values to understand the type of relationship a pair of number shares. For example, less than, greater than, equal to, etc. Let’s see them one by one
- Equal to operator: Represented as ‘==’, the equal to operator checks whether the two given operands are equal or not. If so, it returns true. Otherwise, it returns false. For example, 5==5 will return true.
- Not equal to operator: Represented as ‘!=’, the not equal to operator checks whether the two given operands are equal or not. If not, it returns true. Otherwise, it returns false. It is the exact boolean complement of the ‘==’ operator. For example, 5!=5 will return false.
- Greater than operator: Represented as ‘>’, the greater than operator checks whether the first operand is greater than the second operand or not. If so, it returns true. Otherwise, it returns false. For example, 6>5 will return true.
- Less than operator: Represented as ‘<‘, the less than operator checks whether the first operand is lesser than the second operand. If so, it returns true. Otherwise, it returns false. For example, 6<5 will return false.
- Greater than or equal to operator: Represented as ‘>=’, the greater than or equal to operator checks whether the first operand is greater than or equal to the second operand. If so, it returns true else it returns false. For example, 5>=5 will return true.
- Less than or equal to operator: Represented as ‘<=’, the less than or equal to operator checks whether the first operand is less than or equal to the second operand. If so, it returns true else false. For example, 5<=5 will also return true.
Examples:
C
// C program to demonstrate working of relational operators#include <stdio.h>int main(){ int a = 10, b = 4; // greater than example if (a > b) printf("a is greater than b\n"); else printf("a is less than or equal to b\n"); // greater than equal to if (a >= b) printf("a is greater than or equal to b\n"); else printf("a is lesser than b\n"); // less than example if (a < b) printf("a is less than b\n"); else printf("a is greater than or equal to b\n"); // lesser than equal to if (a <= b) printf("a is lesser than or equal to b\n"); else printf("a is greater than b\n"); // equal to if (a == b) printf("a is equal to b\n"); else printf("a and b are not equal\n"); // not equal to if (a != b) printf("a is not equal to b\n"); else printf("a is equal b\n"); return 0;} |
C++
// C++ program to demonstrate working of logical operators#include <iostream>using namespace std;int main(){ int a = 10, b = 4; // greater than example if (a > b) cout << "a is greater than b\n"; else cout << "a is less than or equal to b\n"; // greater than equal to if (a >= b) cout << "a is greater than or equal to b\n"; else cout << "a is lesser than b\n"; // less than example if (a < b) cout << "a is less than b\n"; else cout << "a is greater than or equal to b\n"; // lesser than equal to if (a <= b) cout << "a is lesser than or equal to b\n"; else cout << "a is greater than b\n"; // equal to if (a == b) cout << "a is equal to b\n"; else cout << "a and b are not equal\n"; // not equal to if (a != b) cout << "a is not equal to b\n"; else cout << "a is equal b\n"; return 0;} |
Output:
a is greater than b a is greater than or equal to b a is greater than or equal to b a is greater than b a and b are not equal a is not equal to b
Time Complexity: O(1)
Auxiliary Space: O(1)
Logical Operators:
They are used to combine two or more conditions/constraints or to complement the evaluation of the original condition under consideration. They are described below:
- Logical AND operator: The ‘&&’ operator returns true when both the conditions under consideration are satisfied. Otherwise, it returns false. For example, a && b returns true when both a and b are true (i.e. non-zero).
- Logical OR operator: The ‘||’ operator returns true even if one (or both) of the conditions under consideration is satisfied. Otherwise, it returns false. For example, a || b returns true if one of a or b, or both are true (i.e. non-zero). Of course, it returns true when both a and b are true.
- Logical NOT operator: The ‘!’ operator returns true the condition in consideration is not satisfied. Otherwise, it returns false. For example, !a returns true if a is false, i.e. when a=0.
Examples:
C
// C program to demonstrate working of logical operators#include <stdio.h>int main(){ int a = 10, b = 4, c = 10, d = 20; // logical operators // logical AND example if (a > b && c == d) printf("a is greater than b AND c is equal to d\n"); else printf("AND condition not satisfied\n"); // logical OR example if (a > b || c == d) printf("a is greater than b OR c is equal to d\n"); else printf("Neither a is greater than b nor c is equal " " to d\n"); // logical NOT example if (!a) printf("a is zero\n"); else printf("a is not zero"); return 0;} |
C++
// C++ program to demonstrate working of// logical operators#include <iostream>using namespace std;int main(){ int a = 10, b = 4, c = 10, d = 20; // logical operators // logical AND example if (a > b && c == d) cout << "a is greater than b AND c is equal to d\n"; else cout << "AND condition not satisfied\n"; // logical OR example if (a > b || c == d) cout << "a is greater than b OR c is equal to d\n"; else cout << "Neither a is greater than b nor c is equal " " to d\n"; // logical NOT example if (!a) cout << "a is zero\n"; else cout << "a is not zero"; return 0;} |
Output:
AND condition not satisfied a is greater than b OR c is equal to d a is not zero
Time Complexity: O(1)
Auxiliary Space: O(1)
Short-Circuiting in Logical Operators:
- In the case of logical AND, the second operand is not evaluated if the first operand is false. For example, program 1 below doesn’t print “GeeksQuiz” as the first operand of logical AND itself is false.
C
#include <stdbool.h>#include <stdio.h>int main(){ int a = 10, b = 4; bool res = ((a == b) && printf("GeeksQuiz")); return 0;} |
C++
#include <iostream>using namespace std;int main(){ int a = 10, b = 4; bool res = ((a == b) && cout << "GeeksQuiz"); return 0;} |
Output:
No Output
- But the below program prints “GeeksQuiz” as the first operand of logical AND is true.
C
#include <stdbool.h>#include <stdio.h>int main(){ int a = 10, b = 4; bool res = ((a != b) && printf("GeeksQuiz")); return 0;} |
C++
#include <iostream>using namespace std;int main(){ int a = 10, b = 4; bool res = ((a != b) && cout << "GeeksQuiz"); return 0;} |
Output
GeeksQuiz
Time Complexity: O(1)
Auxiliary Space: O(1)
- In the case of logical OR, the second operand is not evaluated if the first operand is true. For example, program 1 below doesn’t print “GeeksQuiz” as the first operand of logical OR itself is true.
C
#include <stdbool.h>#include <stdio.h>int main(){ int a = 10, b = 4; bool res = ((a != b) || printf("GeeksQuiz")); return 0;} |
C++
#include <iostream>using namespace std;int main(){ int a = 10, b = 4; bool res = ((a != b) || cout << "GeeksQuiz"); return 0;} |
Output:
No Output
Time Complexity: O(1)
Auxiliary Space:O(1)
- But the below program prints “GeeksQuiz” as the first operand of logical OR is false.
C
#include <stdbool.h>#include <stdio.h>int main(){ int a = 10, b = 4; bool res = ((a == b) || printf("GeeksQuiz")); return 0;} |
C++
#include <iostream>using namespace std;int main(){ int a = 10, b = 4; bool res = ((a == b) || cout << "GeeksQuiz"); return 0;} |
Output
GeeksQuiz
Time Complexity: O(1)
Auxiliary Space: O(1)
Quiz on Operators in C
This article is contributed by Ayush Jaggi. Please write comments if you find anything incorrect, or if you want to share more information about the topic discussed above
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