Step by Step solution about How to resolve the algorithm Sequence of primes by trial division step by step in the C programming language

This C program finds prime numbers within a specified range and calculates their sum. A step-by-step breakdown below:

1. Header File:

   • #include <stdio.h>: Includes the standard input-output library for input and output operations.

2. isPrime Function:

   • unsigned int isPrime(unsigned int n): This function checks if an input number n is prime.
   • It returns 1 if n is prime, and 0 otherwise.
   • If n is less than 2 or even (apart from 2), it returns 0.
   • It iterates through odd numbers up to the square root of n and checks if n is divisible by any of these numbers. If it finds a divisor, it returns 0; otherwise, it returns 1.

3. main Function:

   • It starts by declaring necessary variables:
     • unsigned int l, u, i, sum = 0;: These variables will be used for the range and sum of prime numbers.
   • It prompts the user to input a range using scanf("%ld%ld", &l, &u). l represents the lower bound, and u represents the upper bound.
   • It enters a loop from i = l to u to check for prime numbers.
   • For each value of i, it calls the isPrime function to check if i is prime. If isPrime(i) returns 1, it means i is prime.
   • If i is prime, it prints the prime number and increments the sum variable.
   • Finally, it displays the count of prime numbers found within the given range and their sum.

#include<stdio.h>

int isPrime(unsigned int n)
{
	unsigned int num;
	
	if ( n < 2||!(n & 1)) 
		return n == 2;

	for (num = 3; num <= n/num; num += 2)
		if (!(n % num)) 
			return 0;
	return 1;
}

int main()
{
	unsigned int l,u,i,sum=0;
	
	printf("Enter lower and upper bounds: ");
	scanf("%ld%ld",&l,&u);
	
	for(i=l;i<=u;i++){
		if(isPrime(i)==1)
			{
				printf("\n%ld",i);
				sum++;
			}
	}
	
	printf("\n\nPrime numbers found in [%ld,%ld] : %ld",l,u,sum);
	
	return 0;
}