# Prime Number Program in C – C Program for Prime Number

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;
}
```

### Output ### 2 Responses

1. sowji at | | Reply

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

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