# C#: Calculate the sum of the series [ x - x^3 + x^5 - x^7 + x^9 -.....]

## C# Sharp For Loop: Exercise-24 with Solution

Write a program in C# Sharp to find the sum of the series [ x - x^3 + x^5 - x^7 + x^9 - ........].

**Sample Solution**:-

**C# Sharp Code:**

```
using System; // Importing necessary namespace
public class Exercise24 // Declaration of the Exercise24 class
{
public static void Main() // Main method, entry point of the program
{
double x, sum, ctr, p, term; // Declaration of variables x, sum, ctr, p, term as double
int i, n; // Declaration of variables i and n as integers
Console.Write("\n\n"); // Displaying new lines
Console.Write("Calculate the sum of the series [ x - x^3 + x^5 - x^7 + x^9 - .....]:\n"); // Displaying the purpose of the program
Console.Write("------------------------------------------------------------"); // Displaying a separator
Console.Write("\n\n");
Console.Write("Input the value of x :"); // Prompting the user to input the value of x
x = Convert.ToInt32(Console.ReadLine()); // Reading the value of x entered by the user
Console.Write("Input number of terms : "); // Prompting the user to input the number of terms
n = Convert.ToInt32(Console.ReadLine()); // Reading the number of terms entered by the user
term = 1; // Initializing term with 1
sum = 0; // Initializing sum with 0
// Loop to calculate the sum of the series
for (i = 1, p = 1; i < n + 1; i++)
{
ctr = Math.Pow(x, p); // Calculating x raised to the power p
sum = sum + ctr * term; // Adding the current term to the sum
term = term * (-1); // Changing the sign of the term for the next iteration
p = p + 2; // Increasing power by 2 for the next iteration
}
// Displaying the result
Console.Write("\nThe sum = {0}\nNumber of terms = {1}\nThe value of x = {2}\n", sum, n, x);
}
}
```

Sample Output:

Calculate the sum of the series [ x - x^3 + x^5 - x^7 + x^9 - .....]: ------------------------------------------------------------ Input the value of x :Input number of terms : The sum = 410 Number of terms = 5 The value of x = 2

**Flowchart: **

**C# Sharp Code Editor:**

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