Day 44: Functions in C++ – Definition, Types, and Examples | Class 11 - BSEB Class 11-12 Computer Science: 100-Day Bilingual Guide with MCQs, Solutions and Questions

Day 44 – Functions in C++

Class 11 Computer Science

What is a Function in C++? (C++ में फ़ंक्शन क्या है?)

A function in C++ is a block of reusable code that performs a specific task. Functions make programs modular and easier to understand.
C++ में एक फ़ंक्शन कोड का पुन: उपयोग योग्य ब्लॉक है जो एक विशिष्ट कार्य करता है। फ़ंक्शन प्रोग्राम को मॉड्यूलर और समझने में आसान बनाते हैं।

Advantages of Functions in C++ (C++ में फ़ंक्शन के लाभ)

• Promotes Code Reusability (कोड का पुन: उपयोग को बढ़ावा देता है)
• Improves Modularity (मॉड्यूलैरिटी को बढ़ावा देता है)
• Makes Debugging Easier (डिबगिंग को आसान बनाता है)
• Enhances Code Readability (कोड की पठनीयता में सुधार करता है)

Structure of a Function in C++ (C++ में फ़ंक्शन की संरचना)

A function in C++ has three main components:
C++ में फ़ंक्शन के तीन मुख्य घटक होते हैं:

• Function Declaration (घोषणा): Specifies the function name, return type, and parameters.
• Function Definition (परिभाषा): Contains the actual logic or code.
• Function Call (कॉल): Invokes the function in the main program.

Example:

#include <iostream>
using namespace std;

// Function Declaration
int add(int a, int b);

// Function Definition
int add(int a, int b) {
    return a + b;
}

int main() {
    int result = add(10, 20); // Function Call
    cout << "Result: " << result;
    return 0;
}

Output:

Result: 30

Types of Functions in C++ (C++ में फ़ंक्शन के प्रकार)

• Built-in Functions: Predefined functions like sqrt(), pow().
  उदाहरण: sqrt(), pow()
• User-defined Functions: Functions created by the programmer.
  उदाहरण: int multiply(int a, int b);

Types of User-Defined Functions (उपयोगकर्ता द्वारा परिभाषित फ़ंक्शन के प्रकार)

• Void Functions: Do not return any value.
  Syntax:

  void functionName() {
      // Code
  }
  

• Return Functions: Return a value to the calling function.
  Syntax:

   functionName() {
      // Code
      return value;
  }
  

• Parameterized Functions: Accept parameters to perform operations.
  Syntax:

   functionName( parameter) {
      // Code
      return value;
  }
  

Examples of Functions in C++ (C++ में फ़ंक्शन के उदाहरण)

Example 1: Function to Add Two Numbers

#include <iostream>
using namespace std;

int add(int a, int b) {
    return a + b;
}

int main() {
    int x = 10, y = 20;
    cout << "Sum: " << add(x, y);
    return 0;
}

Output:

Sum: 30

Example 2: Function Without Parameters

#include <iostream>
using namespace std;

void greet() {
    cout << "Hello, World!";
}

int main() {
    greet();
    return 0;
}

Output:

Hello, World!

Example 3: Function with Parameters and Return

#include <iostream>
using namespace std;

float areaOfCircle(float radius) {
    return 3.14 * radius * radius;
}

int main() {
    float r = 5.0;
    cout << "Area: " << areaOfCircle(r);
    return 0;
}

Output:

Area: 78.5

Practice Questions

Multiple Choice Questions (MCQs)

1. Which of the following is a built-in function?
   (a) add() | (b) sqrt() | (c) multiply() | (d) None
2. What does a void function return?
   (a) Integer | (b) Float | (c) Nothing | (d) String
3. Which keyword is used to return a value from a function?
   (a) return | (b) output | (c) void | (d) None
4. What is a user-defined function?
   (a) Provided by libraries | (b) Created by the programmer | (c) Both (a) and (b) | (d) None
5. What will be the output of this code?
   

   #include <iostream>
   using namespace std;
   
   int multiply(int a, int b) {
       return a * b;
   }
   
   int main() {
       cout << multiply(2, 3);
       return 0;
   }
           

   (a) 5 | (b) 6 | (c) Error | (d) None
6. Which function does not return any value?
   (a) Void function | (b) Parameterized function | (c) Built-in function | (d) None
7. What is the difference between a void and a return function?
   (a) Void has parameters | (b) Void returns nothing | (c) Both return values | (d) None
8. Which part of a function contains executable code?
   (a) Declaration | (b) Definition | (c) Call | (d) None
9. What does a parameterized function do?
   (a) Takes inputs | (b) Returns a value | (c) Prints directly | (d) None
10. What is the output of this code?
    

    #include <iostream>
    using namespace std;
    
    void display() {
        cout << "Hello World!";
    }
    
    int main() {
        display();
        return 0;
    }
            

    (a) Hello World! | (b) Error | (c) Nothing | (d) None

Answers to MCQs:

1: (b), 2: (c), 3: (a), 4: (b), 5: (b), 6: (a), 7: (b), 8: (b), 9: (a), 10: (a)

Short Answer Questions

1. What is a function in C++?
   Answer: A function is a reusable block of code that performs a specific task.
2. Write the syntax for declaring and defining a function.
   Answer:

    functionName( parameter) {
       // Code
       return value;
   }
   

3. What are the advantages of using functions in C++?
   Answer: Code reusability, modularity, improved readability, and easy debugging.

Long Answer Questions

1. Explain the types of functions in C++ with examples.
2. Write a program to demonstrate the use of parameterized functions in C++.
3. Discuss the importance of modular programming and how functions contribute to it.