C Exercises: Calculate the harmonic series and their sum

Last update on March 18 2025 13:35:41 (UTC/GMT +8 hours)

19. Harmonic Series and Their Sum

Write a program in C to display the n terms of a harmonic series and their sum.
The series is : 1 + 1/2 + 1/3 + 1/4 + 1/5 ... 1/n terms

This C program displays the first n terms of a harmonic series and calculates their sum. The harmonic series is represented as 1 + 1/2 + 1/3 + 1/4 + 1/5 ... 1/n. The program will prompt the user to input the value of n, then use a loop to compute and display each term, as well as the cumulative sum of the series.

Visual Presentation:

Calculate the harmonic series and their sum

Sample Solution:

C Code:

#include <stdio.h>  // Include the standard input/output header file.

void main()
{
    int i, n;      // Declare variables to store input and loop control.
    float s = 0.0; // Initialize 's' to 0.0 to accumulate the sum.

    // Prompt the user to input the number of terms.
    printf("Input the number of terms : ");
    scanf("%d", &n);  // Read the value of 'n' from the user.

    printf("\n\n");  // Print extra new lines for formatting.

    // Loop to calculate the sum of the series.
    for (i = 1; i <= n; i++)
    {
        if (i < n)
        {
            printf("1/%d + ", i);      // Print the term with a plus sign.
            s += 1 / (float)i;       // Calculate and add the term to the sum.
        }
        if (i == n)
        {
            printf("1/%d ", i);      // Print the last term without a plus sign.
            s += 1 / (float)i;       // Calculate and add the term to the sum.
        }
    }

    // Print the final result.
    printf("\nSum of Series upto %d terms : %f \n", n, s);
}

Output:

Input the number of terms : 5                                                                                 
                                                                                                                                                                                        
1/1 + 1/2 + 1/3 + 1/4 + 1/5                                                                                   
Sum of Series upto 5 terms : 2.283334

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to display the first n terms of the harmonic series and then compute their product.
Write a C program to calculate the harmonic series recursively and display the running total at each step.
Write a C program to output the harmonic series and then compute the average of the terms.
Write a C program to display the harmonic series with formatted output and calculate its sum to a given precision.

C Programming Code Editor:

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