Introduction

     Prime numbers are fundamental in mathematics and find applications in various fields including cryptography and computer science. In this blog post, we'll explore a C program that computes the average of prime numbers up to a given input. We'll delve into the code, understand its components, and discuss how it works. Let's break down the key steps:  


Algorithm

Include Necessary Headers:

Include necessary header files stdio.h and conio.h.

Function Declaration:

Declare a function named average that takes an integer parameter x

Main Function:

  • Declare an integer variable n.
  • Clear the console screen (using clrscr())
  • Prompt the user to enter a number.
  • Read the input number into variable n.
  • Call the average function with the user-input number.
  • Wait for a key press before closing the console (using getch()).

Average Function:

  • Declare variables for loop control (i and j), a flag (flag), and variables for sum (sum) and count (count).
  • Print a message indicating that prime numbers will be displayed.
  • Iterate through numbers from 2 to the input number (x).
  • Check if each number is prime using a nested loop.
  • If a number is prime, print it, update the sum and count, and calculate the average within the loop.
  • After the loop, print the calculated average.
   
      
     
         // Program to find the average of prime numbers
   #include<stdio.h>
   #include<conio.h>
   void average(int x);
          void main() {
            int n;
            clrscr();
            printf("enter a number:\n");
            scanf("%d", &n);
            average(n);
            getch();
          }
          void average(int x) {
            int i, j, flag;
            float result, sum = 0, count = 0;
            printf("the prime numbers are:\n");
            for (i = 2; i <= x; i++) {
              flag = 0;
              for (j = i - 1; j > 1; j--) {
                if (i % j == 0) {
                  flag = 1;
                  break;
                }
              }
              if (flag == 0) {
                printf("%d\n", i);
                sum = sum + i;
                count++;
              }
              result = (sum / count);
            }
            printf("the avg of these prime numbers are=%2f", result);
            getch();
          }


Output

    
         // Output
         enter a number:
         5
         the prime numbers are:
         2
         3
         5
         
         the avg of these prime numbers are=3.333333


Conclusion

     In this blog post, we dissected a C program that calculates the average of prime numbers. Understanding this code helps grasp fundamental concepts of loops, conditions, and function usage in C programming. It also illustrates the process of finding prime numbers and computing averages in a structured manner, offering valuable insights for those learning C programming.