w3resource

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

C For Loop: Exercise-32 with Solution

Write a C program to determine whether a given number is prime or not.

Pictorial Presentation:

Check whether a given number is prime or not

Sample Solution:

C Code:

#include <stdio.h>

void main(){

    int num,i,ctr=0;
    printf("Input  a number: ");
    scanf("%d",&num);
    for(i=2;i<=num/2;i++){
        if(num % i==0){
         ctr++;
            break;
        }
    }
   if(ctr==0 && num!= 1)
        printf("%d is a prime number.\n",num);
   else
      printf("%d is not a prime number",num);
}

Sample Output:

Input  a number: 13                                                                                           
13 is a prime number. 

Flowchart:

Flowchart : Check whether a given number is prime or not

C Programming Code Editor:

Improve this sample solution and post your code through Disqus.

Previous: Write a program in C to display the pattern like a diamond.
Next: Write a C program to display Pascal's triangle

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Share this Tutorial / Exercise on : Facebook and Twitter

C Programming: Tips of the Day

Clearing a char array c

It depends on how you want to view the array. If you are viewing the array as a series of chars, then the only way to clear out the data is to touch every entry. memset is probably the most effective way to achieve this.

On the other hand, if you are choosing to view this as a C/C++ null terminated string, setting the first byte to 0 will effectively clear the string.

Ref : https://bit.ly/3uM7JnL