# C Program For Prime Numbers – Check Whether A Number Is Prime Or Not

**C Program For Prime Numbers** – If you are looking for finding prime numbers in C program, this article will guide you to learn to check whether a number is prime or not in C. Just go through this C program to find prime number tutorial you will be able to write a program to check prime number in C.

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## C Program For Prime Numbers

Check whether a **number is prime or not** in C in C programming language can be done using various techniques, but here in this program, we used three variables to find prime numbers.

### C Program To Find Prime Number Source Code

Copy paste the below **C program to find prime number** source code or write your own logic into C compilers and run the program to see the result.

**Source Code:**

/*C PROGRAM FOR PRIME NUMBER - PRIMENUMBERS.C */ #include <stdio.h> int main() { int n, i, flag = 0; //Variables printf("Enter a positive integer: "); scanf("%d",&n); //Reading input from users for(i=2; i<=n/2; ++i) // Logic for finding prime number { if(n%i==0) { flag=1; break; } } if (flag==0) printf("%d is a prime number.",n); else printf("%d is not a prime number.",n); return 0; }

#### C Program For Prime Numbers Output

After you compile and run the above program, your C compiler asks you to enter a number to check whether a number is a prime number or not. After you enter a positive integer, then it will show output with the result saying the entered number is prime or not like below expected output.

Enter a positive integer: 29

29 is a prime number.

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C Program To Swap Two Numbers Using Two Variables

C Program To Swap Two Numbers Using Three Variables