Logical Operators In C

Types of Logical Operators

There exist primarily three categories of logical operators, which are outlined below:

Here, we will discuss these logical operators one by one.

Logical AND (&&)

In C programming, the logical AND operator checks if both conditions are true. If either condition is false (0), the result is false (0). When both conditions are true (non-zero), the result is true (1). Within if statements, multiple conditions can be evaluated before executing a specific block of code. This operator is useful for combining requirements.

Truth Table Logical AND Operator

The following table displays the functionality of the Logical AND Operator in C.

Syntax

It has the following syntax:

if (condition1 && condition2) 

{

    // Executes if both conditions are true

}

Logical AND (&&) operator Example in C

Let's consider a scenario to demonstrate the Logical AND operator in the C programming language.

Example

#include <stdio.h>



int main() {  //main function

    int age = 25;

    int hasLicense = 1;



    if (age >= 18 && hasLicense) {

        printf("You are allowed to drive.\n");

    } else {

        printf("You are not allowed to drive.\n");

    }



    return 0;

}

Output:

You are allowed to drive.

Explanation:

In this instance, we assess an individual's eligibility to operate a vehicle by employing the logical AND operator. The condition stipulating that the person must be over 18 and possess a valid license acts as evidence that the person is both 18 years old or above and currently holds a license. If both criteria are fulfilled, permission is granted; otherwise, it is denied. This exemplifies the requirement for all conditions to be met for the && operator to operate effectively.

Logical OR(||) Operator

In C programming, the logical OR operator dictates the evaluation of conditions. When at least one condition is met, it results in a true outcome. It will yield false only if none of the conditions are met. This operator is beneficial for executing code when any of the specified conditions are met. It is frequently employed to offer a range of options for decision-making.

Truth Table for Logical OR Operator in C

The table presented below illustrates how the Logical OR Operator functions in the C programming language.

Syntax

It has the following syntax:

if (condition1 || condition2) 

{

    // Executes if at least one condition is true

}

Logical OR (||) Operator Example in C

Let's consider an example to demonstrate the Logical OR (||) Operator in the C programming language.

Example

#include <stdio.h>



int main() {  //main function

    int hasCoupon = 0;

    int isPremiumUser = 1;



    if (hasCoupon || isPremiumUser) {

        printf("You get a discount.\n");

    } else {

        printf("No discount available.\n");

    }



    return 0;

}

Output:

You get a discount.

Explanation:

In this instance, the logical OR operator is employed to verify the suitability of a discount. The eligibility for a discount is determined based on the coupon availability or premium status. The user validates the activation status of either the voucher or premium. The discount is authorized if any of these conditions are met as only one of them must be true.

Logical NOT (!) Operator

In C programming, the NOT operator is used to reverse the logical state of an operand. When applied, a true condition transforms into false, and vice versa. Its primary purpose is to negate conditions within while, if, and loop statements. This operator proves beneficial when we aim to execute code only when a particular condition is not met.

Truth Table for logical NOT(!) Operator in C

The table below illustrates the functionality of the Logical NOT (!) Operator in the C programming language.

Syntax

It has the following syntax:

if (!condition) 

{

    // Executes if the condition is false

}

Logical NOT (!) Operator Example in C

Let's consider a scenario to demonstrate the Logical NOT (!) Operator in the C programming language.

Example

#include <stdio.h>



int main() {  //main function

    int isLoggedIn = 0;



    if (!isLoggedIn) {

        printf("Please log in to continue.\n");

    } else {

        printf("Welcome back!\n");

    }



    return 0;

}

Output:

Please log in to continue.

Explanation:

In this instance, the software employs the logical NOT operator to ascertain the user's login status. Inverting the original value (which is 0), the condition !isLoggedIn prompts the user to log in if they are not already authenticated. Below is a demonstration of leveraging the (!) operator to reverse a condition's logic.

Example code for all above aspects combined together.

#include <stdio.h>



int main() {    //main function

    int age = 17;

    int hasID = 1;



    if (age >= 18 && hasID) {

        printf("Entry allowed.\n");

    }



    if (age >= 18 || hasID) {

        printf("May be allowed with conditions.\n");

    }



    if (!(age >= 18)) {

        printf("You are underage.\n");

    }



    return 0;

}

Output:

May be allowed with conditions.

You are underage.

Explanation:

In this instance, eligibility is established by considering both the age and identification of an individual. The && operator will grant access solely to individuals who are 18 years of age or older and possess valid identification. Conversely, the || operator offers a chance if at least one condition is satisfied. Upon confirming that the individual is below 18 years old, the operator labels them as underage. Each logical operator manages the output based on a range of criteria.

Advantages of Logical Operators

Several advantages of Logical Operators in C are as follows:

• ✅ Simplify Complex Situations: By enabling the combination of several conditions into a single statement, logical operators help to simplify and deconstruct code.
• ✅ Enhance control flow: They help programmers make decisions by providing accurate checks in control statements such as if and while.
• ✅ In order to increase efficiency, the && and || operators employ short-circuit evaluation, which avoids analyzing words that have already been used. We call this technique "effective evaluation" (short-circuiting).
• ✅ Support for boolean logic is complicated: In order to create and validate algorithms, boolean logic can be implemented using logical operators.
• ✅ Logical operators are essential for iterative and decision-making procedures because they are so commonly used in loops and conditional statements.

Disadvantages of Logical Operators in C

Several disadvantages of Logical Operators in C are as follows:

• ✅ Issues with Complex Expressions' Readability: Code readability may suffer, and debugging may become more difficult if too many logical operators are used in a single line.
• ✅ Logical errors: A small mistake (such as substituting || for &&) might lead to hard-to-detect logical errors.
• ✅ Misapplication of short-circuiting: Relying on short-circuit behavior for side effects (such function calls) may result in tasks being skipped or unanticipated outcomes.
• ✅ Limited to Boolean situations: It may be confusing to use logical operators in non-Boolean reasoning because they are only relevant in Boolean formulations.

Conclusion

In summary, logical operators within the C programming language are crucial for managing program flow by enabling the assessment of various conditions. These operators form the basis of conditional statements like if, for, and while, empowering programmers to craft efficient and flexible code. Proper utilization of logical operators enhances code performance and clarity through short-circuit evaluation and the streamlining of intricate expressions. Conversely, misuse can result in logic flaws, misunderstandings, and unpredictable outcomes. Hence, a thorough comprehension of logical operators is vital for developing coherent, robust, and sustainable C programs.

Logical Operators FAQ'S

1) What are the main logical operators in C?

C provides mainly three logical operators:

• ✅ && (Logical AND)
• ✅ || (Logical OR)
• ✅ ! (Logical NOT)

They are employed to assess expressions that result in true (non-zero) or false (zero).

In C programming, short-circuit evaluation refers to the behavior where the logical operators (&& and ||) do not evaluate the second operand if the outcome can be determined by evaluating the first operand alone.

In short-circuit evaluation, the compiler omits evaluating the second part of an && or || operation when the outcome is already determined by the first part. Consequently, if A evaluates to false in A && B, the compiler does not assess the value of B. Similarly, if A is true in A || B, the compiler bypasses the evaluation of B.

Yes, in C programming language, logical operators can be applied to non-Boolean values.

Yes, in C, any non-zero value is considered true. The logical operators handle numbers in the same way, irrespective of their Boolean declaration.

The distinction between & and && in the C programming language lies in their functionality when used as operators.

Each integer input undergoes a bitwise AND operation using the unary & operator. The evaluation halts as soon as the result is determined by the double && operator, which operates on complete logical expressions. One common error that can lead to intricate and challenging-to-spot problems is intermixing these two operators.

5) Within a C program, where are logical operators commonly utilized?

Since logical operators enable the connection of multiple checks to control program flow, they are commonly employed in conditional statements within if, while, for, and do-while loops.