Q:

Write a C Program to Find Number is Prime or Not using Recursion

robaa
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2022-11-24
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Write a C Program to Find Number is Prime or Not using Recursion. Here’s simple Program to Find Number is Prime or Not using Recursion in C Programming Language.

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robaa
2022-11-24
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Recursion : :

  • Recursion is the process of repeating items in a self-similar way. In programming languages, if a program allows you to call a function inside the same function, then it is called a recursive call of the function.
  • The C programming language supports recursion, i.e., a function to call itself. But while using recursion, programmers need to be careful to define an exit condition from the function, otherwise it will go into an infinite loop.
  • Recursive functions are very useful to solve many mathematical problems, such as calculating the factorial of a number, generating Fibonacci series, etc.

Problem : :

The following C program, using recursion, finds whether the entered number is prime number or not. A prime number is an integer that has no integral factor but itself and 1.

 
 

Below is the source code for C Program to Find Number is Prime or Not using Recursion which is successfully compiled and run on Windows System to produce desired output as shown below :

SOURCE CODE : :

/* C Program to Find Number is Prime or Not using Recursion */


#include <stdio.h>
 
int primeno(int, int);
 
int main()
{
    int num, check;
    printf("Enter a number: ");
    scanf("%d", &num);
    check = primeno(num, num / 2);
    if (check == 1)
    {
        printf("%d is a prime number\n", num);
    }
    else
    {
        printf("%d is not a prime number\n", num);
    }
    return 0;
}
 
int primeno(int num, int i)
{
    if (i == 1)
    {
        return 1;
    }
    else
    {
       if (num % i == 0)
       {
         return 0;
       }
       else
       {
         return primeno(num, i - 1);
       }       
    }
}

Output : :

***************** OUTPUT ****************


***************** FIRST RUN *****************

Enter a number: 675
675 is not a prime number


***************** SECOND RUN *****************

Enter a number: 467
467 is a prime number

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C Recursion Solved Programs – C Programming
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