C program to print prime numbers up to n

In this article we will learn to implement a C program to print prime numbers up to n. A C program is provided below which accepts n as input from user and prints all the prime numbers up to n.

The program is as follows:

#include <stdio.h>
#include <conio.h>
#include <math.h>

int main() 
{
	int n;
	printf("Enter n: ");
	scanf("%d", &n);
	printf("Prime numbers up to %d are: \n", n);
	for(int i = 2; i < n; i++)
	{
		int flag = 0;
		for(int j = 2; j <= sqrt((double)i); j++)
		{
			if(i % j == 0)
			{
				flag = 1;
				break;
			}
		}
		if(flag == 0)
			printf("%d ", i);
	}
	getch();
    return 0;
}

Input and output for the above program is as follows:

Enter n: 25
Prime numbers up to 25 are:
2 3 5 7 11 13 17 19 23

Suryateja Pericherla

Suryateja Pericherla, at present is a Research Scholar (full-time Ph.D.) in the Dept. of Computer Science & Systems Engineering at Andhra University, Visakhapatnam. Previously worked as an Associate Professor in the Dept. of CSE at Vishnu Institute of Technology, India.

He has 11+ years of teaching experience and is an individual researcher whose research interests are Cloud Computing, Internet of Things, Computer Security, Network Security and Blockchain.

He is a member of professional societies like IEEE, ACM, CSI and ISCA. He published several research papers which are indexed by SCIE, WoS, Scopus, Springer and others.