# C program to check prime number or not

List of programs below: c program to check prime number or not using functions, c program to check prime number or not using for loop, c program to check prime number or not using while loop, c program to check prime number or not using switch operator, c program to find prime numbers below n, c program to find prime numbers between  two given numbers, c program to find prime numbers between 1 and 100.

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. eg: 3 is prime number since it it has no factors other than 1 and 3
6 is not a prime since it has factors 2 & 3 other than 1 & 6

## write a c program to check prime number or not using functions

write a c program to check prime number or not using functions

#include<stdio.h>
void main()
{
int n;
printf(” OUTPUT : c program to check a given number is prime or not using functions \n \n” );
printf(” \n enter the no.” );
scanf(“%d”, &n)
void findprime(n);
}

findprime(int num)
{
int i;
boolen temp = 1;
for (i=2; i<num; i++)
{
if (num%i==0)
{
temp=0;
break;
}
temp=1;
}
if (temp==1)
printf(” \n Yes, this is a prime number “);
else
printf(” \n No, this is not a prime number “);
}

## write a C program to check prime number or not using for loop

write a c program to check prime number or not using for loop

#include<stdio.h>
void main()
{
int n,i, temp=1;
printf(” OUTPUT: c program to find whether a given number is prime or not using for loop \n \n” );
printf(” \n enter the no.:” );
scanf(“%d”, &n)
for (i=2; i<n; i++)
{
if (n%i==0)
{
temp=0;
break;
}
temp=1;
}
if (temp==1)
printf(” \n Yes, this is a prime number”);
else
printf(” \n No, this is not a prime number “);
}

## write a c program to check prime number or not using while loop

write a c program to check prime number or not using while loop

#include<stdio.h>
void main()
{
int num,i=2, temp = 1;
printf(” OUTPUT: c program to find whether a given number is prime or not using while loop \n \n”);
printf(” \n enter the no:” );
scanf(“%d”, &num)
while( i<num )
{
if (num%i==0)
{
temp=0;
i++;
break;
}
temp=1;
}
if (temp ==1 )
printf(” \n Yes, this is a prime number”);
else
printf(” \n No, this is not a prime number “);
}

## write a c program to find a number is prime or not using switch operator

write a c program to find a number is prime or not using switch operator

#include<stdio.h>
void main()
{
int n;
printf(“OUTPUT: c program to find whether a given number is prime or not using switch \n \n” );
printf(” \n enter no. \n” );
scanf(“%d”, &no)
for (i=2; i<no; i++)
{
if (no%i==0)
{
flag=0;
break;
}
flag=1;
}
switch (flag)
{
case 0:
printf(” \n Yes, this is a prime number”);
break;

case 1:
printf(” \n No, this is not a prime number “);
break;
}
}

## write a c program to generate prime numbers below n

write a c program to generate prime numbers below n / write a c program to generate prime numbersless than n

#include<stdio.h>
void main()
{
int n;
printf(“OUTPUT: c program to generate prime numbers below n \n \n” );
printf(” \n enter no. \n” );
scanf(“%d”,& n)
for(int i=2;i<n;i++)
void findprime(i);
getch();
}

void findprime(int num)
{
int i;
for (i=2; i<num/2; i++)
{
if (num%i==0)
{
break;
}
printf(” \t  %d  “, num);
}
}

## write a c program to find prime numbers between two given numbers

write a c program to find prime numbers between two given numbers

#include<stdio.h>
void main()
{
int n,m;
printf(“OUTPUT: c program to find prime numbers between two given numbers” );
printf(” \n enter first no. \n” );
scanf(“%d”, &n);
printf(” \n enter second no. \n” );
scanf(“%d”, &m)
if(n>m)
{
for (i=m;i<n;i++)
void findprime(i);
}
else
{
for (i=n;i<m;i++)
void findprime(i);
}
getch():
}

void findprime(int num)
{
int i;
for (i=2; i<num/2; i++)
{
if (num%i==0)
{
break;
}
printf(” \t  %d  “, num);
}
}

## write a c program to find prime numbers between 1 and 100

write a c program to find prime numbers between 1 and 100

#include<stdio.h>
void main()
{
int i;
printf(“OUTPUT:c program to find prime numbers between 1 and 100″ );
// for c program to find prime numbers between 1 and 1000 use 1000 in place of 100
for (i=1;i<=100;i++)
void findprime(i);
getch():
}

void findprime(int num)
{
int i;
for (int i=2; i<num/2; i++)
{
if (num%i==0)
{
break;
}
printf(” \t  %d  “, num);
}
}

## write a c program to check prime number or not using call by reference

write a c program to check prime number or not using call by reference

#include<stdio.h>
void main()
{
int *n;
printf(” OUTPUT : c program to check a given number is prime or not using call by reference \n \n” );
printf(” \n enter the no.” );
scanf(“%d”, n)
void findprime(*n);
}

findprime(int *num)
{
int i;
boolen temp = 1;
for (i=2; i<*num; i++)
{
if (*num%i==0)
{
temp=0;
break;
}
temp=1;
}
if (temp==1)
printf(” \n Yes, this is a prime number “);
else
printf(” \n No, this is not a prime number “);
}