Logical Operators in C
These operators are used to combine relational expressions. The Output: of a logical expression is always 1 or 0.
Various logical operators in C language are as follows:
| Operator | Name of Operator | Purpose |
| && | Logical AND | To combine two relational expressions. If any of the input is 0, Output: would be 0. If all the inputs are 1, Output: would be 1. |
| || | Logical OR | To combine two relational expressions. If any of the input is 1, Output: would be 1. If all the inputs are 0, Output: would be 0. |
| ! | Logical NOT | It is used to reverse the Output: of a relational or logical expression. If input is 1, Output: would be 0 and vice versa. |
1. Logical And(&&)
Logical And operator is represented as double ampersand sign (&&). It is used to combine two relational expressions.
If any input of this operator is 0, Output would be 0.
If all the inputs of this operator are 1, Output would be 1
Truth table for Logical AND operator
| Input1 | Input2 | Output |
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
Example
10 >3 && 10>5 = 1
10 >3 && 10<5 = 0
10 <3 && 10<5 = 0
2. Logical OR(||)
Logical OR operator is represented as double pipe sign (||). It is used to combine two relational expressions.
If any input of this operator is 1, Output would be 1.
If all the inputs of this operator are 0, Output would be 0
Truth table for Logical OR operator
| Input1 | Input2 | Output |
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 1 |
Example
10 >3 || 10>5 = 1
10 >3 || 10<5 = 1
10 <3 || 10<5 = 0
3. Logical NOT(!)
Logical NOT operator is represented as sign of exclamation(!).
It is used to reverse the output of a relational expression or logical expression.
If input of this operator is 1, Output would be 0.
If input of this operator is 0, Output would be 1.
Truth table for Logical NOT operator
| Input | Output |
| 0 | 1 |
| 1 | 0 |
Example
!(10 >3 && 10>5) = 0
!(10<5) = 1
!(10 <3 || 10<5) = 1
| Program to demonstrate logical operators. | Output (Line Wise) |
| #include<stdio.h> #include<conio.h> int main() { int a,b,c; |
|
| printf(“\nEnter value of a=”); scanf(“%d”,&a); | Enter value of a=10 |
| printf(“\nEnter value of b=”); scanf(“%d”,&b); | Enter value of b=3 |
| printf(”\n%d”, (a>0 && b>0); | 1 |
| printf(”\n%d”, (a<0 && b>0); | 0 |
| printf(”\n%d”, (a>0 || b<0); | 1 |
| printf(”\n%d”, (a<0 && b<0); | 0 |
| printf(”\n%d”, !(a>0); | 0 |
| printf(”\n%d”, !(a<0 && b>0); | 1 |
| getch(); return (0); } |