# 1. Introduction

The Fibonacci series is one of the most well-known patterns in mathematics. It starts with *0* and *1*, and each subsequent number in the series is the sum of the two preceding numbers. This sequence finds its significance in many natural phenomena, from the arrangement of leaves on a plant to the branching of trees. In this post, we'll walk through a *C++* program that generates the Fibonacci series up to *n* numbers.

# 2. Program Overview:

Our program will follow these steps:

1. Prompt the user to provide the value of *n*.

2. Check if *n* is *1* or *2* and handle these cases separately.

3. If *n* is more than *2*, start from the third term and generate the sequence iteratively until the *n*-th term.

4. Display the Fibonacci sequence.

# 3. Code Program

```
#include <iostream>
using namespace std;
// Function to generate the Fibonacci series up to n terms
void fibonacci(int n) {
long long t1 = 0, t2 = 1, nextTerm; // Initialize variables for the first two terms
for (int i = 1; i <= n; ++i) { // Iterate from 1 to n terms
if(i == 1) {
cout << t1 << ", "; // Output the first term (0)
continue; // Skip the rest of the loop and continue to the next iteration
}
if(i == 2) {
cout << t2 << ", "; // Output the second term (1)
continue; // Skip the rest of the loop and continue to the next iteration
}
nextTerm = t1 + t2; // Calculate the next term in the sequence
t1 = t2; // Update t1 to the value of t2
t2 = nextTerm; // Update t2 to the value of the calculated nextTerm
cout << nextTerm << ", "; // Output the current term
}
}
int main() {
int n;
cout << "Enter the number of terms: ";
cin >> n; // Read the input number of terms from the user
cout << "Fibonacci Series: ";
fibonacci(n); // Call the fibonacci function to generate and display the series
return 0; // Indicate successful execution by returning 0
}
```

### Output:

Enter the number of terms: 10 Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34,

# 4. Step By Step Explanation

1. **Headers and Namespace:** We begin by including the *iostream* library for input-output operations and declare usage of the standard namespace.

2. **Fibonacci Function:** The function *fibonacci* takes an integer *n* and prints the Fibonacci sequence up to *n* terms. We utilize three variables: *t1*, *t2*, and *nextTerm* to calculate and store values in the series. Loops and conditions help us generate the sequence.

3. **Main Function:** This is where the program starts its execution. We declare the variable *n* to store the number of terms.

4. **User Input: **A prompt is displayed using *cout*, and the user's response is acquired with *cin*.

5. **Printing the Sequence:** We call the *fibonacci* function and subsequently display the resulting series.

6. **Program Termination:** The program concludes with a return value of *0*, indicating successful execution.

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