Logical AND Operator in C

Logical operators perform logical operations on a given expression by joining two or more expressions or conditions. It can be used in various relational and conditional expressions. This operator is based on Boolean values to logically check the condition, and if the conditions are true, it returns 1. Otherwise, it returns 0 (False). In C programming, logical operators are classified into three types such as the logical AND (&&) operator, the logical OR operator (||), and the logical NOT (!) operator. Here, we learn about the Logical AND operator and its various examples in the C programming language.

Logical AND Operator

The logical AND operator is represented as the '&&' double ampersand symbol. It checks the condition of two or more operands by combining in an expression, and if all the conditions are true, the logical AND operator returns the Boolean value true or 1. Else it returns false or 0.

Note: If the value of both is non-zero, the condition will remain true. Otherwise, the logical AND (&&) operator returns 0 (false).

Syntax

There are two conditions in the above syntax, condition1 and condition2, and in between the double (&&) ampersand symbol. If both the conditions are true, the logical AND operator returns Boolean value 1 or true. Otherwise, it returns false.

Truth table of the Logical AND (&&) operator

A	B	A && B
1	1	1
1	0	0
0	1	0
0	0	0

Example 1: Program to demonstrate the Logical AND Operator in C

#include <stdio.h>
#include <conio.h>

int main ()
{
	// declare variable
	int n = 20;
	
	// use Logical AND (&&) operator to check the condition
	printf (" %d \n", (n == 20 && n >= 8)); // condition is true, therefore it returns 1
	printf (" %d \n", (n >= 1 && n >= 20));
	printf (" %d \n", (n == 10 && n >= 0));
	printf (" %d \n", (n >= 20 && n <= 40));
	
	return 0;
} 

Output

Example 2: Program to find the largest number using the Logical AND operator

#include <stdio.h>
#include <conio.h>
int main ()
{
// declare integer type variable
int x, y, z;
printf (" Enter the first number: ");
scanf ("%d", &x);
printf (" Enter the second number: ");
scanf ("%d", &y);
printf (" Enter the third number: ");
scanf ("%d", &z);

// use logical AND operator to validate the condition
if ( x >= y && x >= z )
{
printf (" %d is the largest number of all. ", x);
}
else if ( y >= x && y >= z)
{
printf (" %d is the largest number of all. ", y);
}
else
{
	printf ( " %d is the largest number of all. ", z);
}
return 0;
}

Output

Enter the first number: 20
Enter the second number: 10
Enter the third number: 50
50 is the largest number of all

Example 3: Program to use the Logical AND (&&) operator to check whether the user is teenager or not.

#include <stdio.h>
#include <conio.h>

int main ()
{
	// declare variable
	int age;
	
	printf (" Enter the age: ");
	scanf (" %d", &age); // get age
	
	// use logical AND operator to check more than one condition
	if ( age >= 13 && age <= 19) 
	{
		printf (" %d is a teenager age. ", age);
	}
	else
	{
		printf (" %d is not a teenager age. ", age);
	}
	
	return 0;
}

Output

Enter the age: 17
17 is a teenager age.

2nd execution:
Enter the age: 10
10 is not a teenager age.

Example 4: Program to validate whether the entered number is in the defined range or not.

#include <stdio.h>

int main ()
{
	int num;
	printf (" Enter a number between 1 to 50: ");
	scanf (" %d", &num); //get the number
	
	// use logical AND operator to check condition
	if ( (num > 0 ) && (num <= 50))
	{
		printf (" The entered number is in the range 0 and 50. ");
	}
	else if ( ( num > 50 ) && ( num <= 100))
	{
		printf (" The entered number is in the range 50 and 100. ");
	}
	else
	{
		printf (" Please enter the number is in the defined range. ");
	}
	return 0;
	
 }

Output

Enter a number between 1 to 50: 19
The entered number is in the range 0 and 50.

2nd Run 
Enter a number between 1 to 50:
51
The entered number is in the range 50 and 100.

3rd execution:
Enter a number between 1 to 50:
0
Please enter the number is in the defined range.

Example 5: Program to validate the username and password entered by the user is correct or not using the predefined username and password.

#include <stdio.h>
#include <string.h>

// use #define macro to define the values for UserName and Password
#define UserName "system"
#define Password "admin@123"

int main ()
{
// declare character type array
char un[50], pass[50];
// take UserName and Password from user
printf ( " Enter the username: " );
scanf (" %s", un);
printf ( " Enter the password: " );
scanf (" %s", pass);

// use if statement and Logical AND operator to validate the condition
if (strcmp (UserName, un) == 0 && strcmp (Password, pass) == 0)
{
printf (" \n The user's credentials are correct. ");
}
else
{
printf ( " \n The user's credentials are incorrect. ");
}
return 0;
}  

Output

Enter the username: system
Enter the password: admin@123

The user's credentials are correct.

2nd execution
Enter the username: system
Enter the password: admin@1234

The user's credentials are incorrect.

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