# C Exercises: Check whether a number is a prime number or not

## C Function : Exercise-7 with Solution

Write a program in C to check whether a number is a prime number or not using the function.
Test Data :
Input a positive number : 5
Expected Output :

``` The number 5 is a prime number.
```

C Code:

```#include<stdio.h>
int PrimeOrNot(int);
int main()
{
int n1,prime;
printf("\n\n Function : check whether a number is prime number or not :\n");
printf("---------------------------------------------------------------\n");

printf(" Input a positive number : ");
scanf("%d",&n1);
prime = PrimeOrNot(n1);
if(prime==1)
printf(" The number %d is a prime number.\n",n1);
else
printf(" The number %d is not a prime number.\n",n1);
return 0;
}
int PrimeOrNot(int n1)
{
int i=2;
while(i<=n1/2)
{
if(n1%i==0)
return 0;
else
i++;
}
return 1;
}
```

C Practice online:

```#include<stdio.h>
int PrimeOrNot(int);
int main()
{
int n1,prime;
printf("\n\n Function : check whether a number is prime number or not :\n");
printf("---------------------------------------------------------------\n");

printf(" Input a positive number : ");
scanf("%d",&n1);
prime = PrimeOrNot(n1);
if(prime==1)
printf(" The number %d is a prime number.\n",n1);
else
printf(" The number %d is not a prime number.\n",n1);
return 0;
}
int PrimeOrNot(int n1)
{
int i=2;
while(i<=n1/2)
{
if(n1%i==0)
return 0;
else
i++;
}
return 1;
}
```

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