C Program to Display Prime Numbers Between Two numbers

C programming is a general purpose widely used high level programming language. Almost all types of computer programs are written in this language. It is the basic programming language. Write a C program to find Prime number between two numbers inputted by user. We will also learn how to display prime number between 1 to n numbers. Now first we learn about prime numbers.

Prime no between two no

  • Write a C program to print all prime numbers between 1 to N using for loop.
  • Write in C to print prime numbers between 1 and 100.

Required Knowledge

  • C print f and scan-f functions
  • For loop in C

Define Prime Number in C Programmings

A Prime number is a natural number greater than 1 that is only divisible by either 1 or itself. All numbers other than prime numbers are known as composite numbers. There are infinitely many prime numbers, here is the list of first few prime numbers
2 3 5 7 11 13 17 19 23 29 31 37….

Step 1. In step 1 processors are given to include header file for prime numbers
Step 2. We used main function
Step 3.  we have declared variables
Step 4. Two numbers are inputted with the help of print f and scan f fiction.
Step 5. In this step external loop is given here we for loop which increase their value from 1 to next and so on

Algorithm for Prime no

we just write algorithm for 1 to n number you can change it according to your need and requirements
Algorithm.
Algorithm to check whether a number is prime or not
Let, N be a positive number.

  • For every number i, between 2 to N/2(2<= i <= N/2) check whether I divide N completely(check If I is a factor of N).
  • If (N % i == 0), then N cannot be a Prime number.
  • If none of the number between 2 to N/2 divides N completely then N is a prime number.

Example of Program

#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
long i,prime,j,n1,n2;
printf("Enter start and end numbers for prime");
scanf("%ld %ld",&n1,&n2);
for(i=n1;i<=n2;i++)
{
 prime=1;
 for(j=2;j<i;j++)
 {
 if(i%j==0)
 {
 prime=0;
 break;
 }
 }
 if(prime==1)
 printf("%ld\t",i);
}
getch();
}

Output

Enter two numbers(intervals): 20
50
Prime numbers between 20 and 50 are: 23 29 31 37 41 43 47