C nested if Statement

Posted in C Tutorial

Updated on Sep 13, 2024

By Mari Selvan

👁️ 26 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

The if statement is fundamental to decision-making in C programming. Sometimes, you may need to test multiple conditions in a program, which can be achieved using nested if statements.

This guide will provide an in-depth look at nested if statements, their syntax, and practical examples of their usage.

🤔 What is a Nested if Statement?

A nested if statement is an if statement placed inside another if statement. This allows you to check multiple conditions and perform different actions based on those conditions.

🔑 Key Features

Multiple Condition Checking: Allows testing of multiple conditions.
Hierarchical Decision Making: Supports complex decision-making processes.
Flexibility: Offers flexibility in defining conditions and actions.

💡 Syntax

The syntax for nested if statements involves placing one if statement inside another. Here’s a general structure:

example.c

Copied

if (condition1) {
  // Executes when condition1 is true
  if (condition2) {
    // Executes when condition2 is true
  }
}

Example: Basic Nested if Statement

example.c

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#include <stdio.h>

int main() {
  int num = 10;

  if (num > 0) {
    printf("Number is positive\n");

    if (num % 2 == 0) {
      printf("Number is even\n");
    }
  }

  return 0;
}

💻 Output

In this example, the program checks if num is positive and then checks if it is even.

Output

Number is positive
Number is even

Practical Examples

Example 1: Checking Multiple Conditions

example.c

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#include <stdio.h>

int main() {
  int age = 20;
  int grade = 85;

  if (age >= 18) {
    if (grade >= 60) {
      printf("Eligible for admission\n");
    } else {
      printf("Not eligible due to low grade\n");
    }
  } else {
    printf("Not eligible due to age\n");
  }

  return 0;
}

This program checks if a person is eligible for admission based on age and grade.

Example 2: Nested if-else Statements

example.c

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#include <stdio.h>

int main() {
  int number = -5;

  if (number >= 0) {
    if (number == 0) {
      printf("Number is zero\n");
    } else {
      printf("Number is positive\n");
    }
  } else {
    printf("Number is negative\n");
  }

  return 0;
}

In this example, the program distinguishes between zero, positive, and negative numbers using nested if-else statements.

Common Pitfalls and Best Practices

Readability:

Nested if statements can become complex and hard to read. To improve readability:
- Indentation: Use proper indentation to highlight nested structures.
- Comments: Add comments to explain the logic of complex conditions.
Logical Complexity:

Avoid excessive nesting to prevent logical complexity. Consider using logical operators (&&, ||) or else if for simpler conditions.
example.c
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```
#include <stdio.h>

int main() {
  int num = 10;

  if (num > 0 && num % 2 == 0) {
    printf("Number is positive and even\n");
  }

  return 0;
}
```
This example simplifies the nested if statement by combining conditions using the logical && operator.

Nested if-else-if Ladder:

In cases with multiple conditions, consider using an if-else-if ladder for better readability and structure.

example.c

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#include <stdio.h>

int main() {
  int marks = 75;

  if (marks >= 90) {
    printf("Grade: A\n");
  } else if (marks >= 80) {
    printf("Grade: B\n");
  } else if (marks >= 70) {
    printf("Grade: C\n");
  } else if (marks >= 60) {
    printf("Grade: D\n");
  } else {
    printf("Grade: F\n");
  }

    return 0;
}

This example uses an if-else-if ladder to assign grades based on marks.

🎉 Conclusion

Nested if statements are a powerful tool in C programming for handling multiple conditions and making complex decisions. By understanding their syntax and best practices, you can write more efficient and readable code.