FAQs in C: Find the Sum of Natural Numbers
FAQs in C: Find the Sum of Natural Numbers

FAQs in C: Find the Sum of Natural Numbers

Algorithm to Find the Sum of Natural Numbers

Plaintext
Step 1: Start
Step 2: Input: Read a positive integer n from the user.
Step 3: Process:
        - Initialize variables sum to store the sum and i for iteration.
        - Initialize sum to 0.
        
        - Use a loop to iterate from 1 to n:
          (i) Add the current value of i to sum.
        
        - After the loop, sum will contain the sum of natural numbers    
          from 1 to n.

Step 4: Output: Display the sum of natural numbers up to n.
Step 5: End

C Program to Find the Sum of Natural Numbers

C
#include <stdio.h>

int main() {
    int n, sum = 0, i;

    // Step 2: Read a positive integer from the user
    printf("Enter a positive integer: ");
    scanf("%d", &n);

    // Step 3: Calculate the sum of natural numbers up to n
    for (i = 1; i <= n; i++) {
        sum += i;   // Add i to sum
    }

    // Step 4: Output the sum of natural numbers
    printf("The sum of natural numbers up to %d is %d.\n", n, sum);

    // Step 5: End
    return 0;
}

Explanation of Each Step

Include Header:

C
#include <stdio.h>

  • This line includes the standard input-output library.

Main Function:

C
int main() {

  • The main function is the entry point of the C program.

Variable Declaration:

C
int n, sum = 0, i;

  • Three integer variables are declared: n to store the user input, sum to store the sum of natural numbers, and i for iteration in the loop.

Reading Input:

C
printf("Enter a positive integer: ");
scanf("%d", &n);
  • printf prompts the user to enter a positive integer.
  • scanf reads the integer and stores it in the variable n.

Calculating the Sum of Natural Numbers:

C
   for (i = 1; i <= n; i++) {
       sum += i;   // Add i to sum
   }
  • The for loop initializes i to 1 and iterates as long as i is less than or equal to n.
  • In each iteration:
    • i is added to sum using the compound assignment operator (+=).

Output:

    C
    printf("The sum of natural numbers up to %d is %d.\n", n, sum);

    • printf prints the sum of natural numbers up to n using the format specifier %d for integers.

    End:

      C
      return 0;

      • This line indicates successful completion of the program.

      This program effectively calculates and displays the sum of natural numbers up to a given positive integer n using a simple for loop. The algorithm ensures that each natural number from 1 to n is added to the sum, providing the cumulative total.


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