Prime number program in c along with the output is given below.

## About Prime Numbers

Any natural number like 1, 2, 3, etc. is called a prime or a prime number if it is greater than 1 and can only be divided by 1 and the number itself.

For example,

2, 3, 5, 7, 11, 13, 17, 19, 23, 29,…, and so on

It should be noted that the natural numbers greater than 1 that are not prime numbers are called composite.

## Prime Number Program in C – Program 1

The below c program for prime number takes an integer as input, and checks whether the input number is a prime number or not.

#include<stdio.h> void main() { int x,i,flag=0; printf("Enter number to be checked whether it is prime or notn"); scanf("%d",&x); if(x>0) { for(i=2; i<=x/2; i++) { if(x%i==0) { flag=1; break; } } if(flag==0 && x!=1) printf("Number is primen"); else printf("Number is not primen"); } else printf("Please enter number greater than 0n"); getch(); }

### Output

## Prime Number Program in C – Program 2

The below c program for prime number prints the total number of prime numbers provided as an input by the user.

#include<stdio.h> void main() { int n,count=1,i,flag=0; printf("Enter total number of prime numbers to be generatedn"); scanf("%d",&n); printf("List of prime numbersn"); for(i=2; count<=n; i++) { flag=prime(i); if(flag==1) { printf("%dn",i); count++; } } getch(); } int prime(int x) { int j; for(j=2; j<=x/2; j++) { if(x%j==0) { return 0; break; } } if(j>x/2) return 1; }

## Prime Number Program in C – Program 3

The below c program for prime number prints all the prime numbers between a range as mentioned by the user.

#include<stdio.h> void main() { int start,end,i,flag=0; printf("Enter range between which prime numbers are to be generatedn"); scanf("%d%d",&start,&end); printf("List of prime numbers between %d and %dn",start,end); for(i=start; i<=end; i++) { flag=prime(i); if(flag==1 && i!=1) printf("%dn",i); } getch(); } int prime(int x) { int j; for(j=2; j<=x/2; j++) { if(x%j==0) { return 0; break; } } if(j>x/2) return 1; }

program input give little more easy .programs which are give are difficult to understand.