Program In C Language To Find Number Is Prime or not.

//Program to find number is prime or not

1. #include<stdio.h> 2. #include<conio.h> 3. void main() 4. { 5. int num,i,n; 6. clrscr(); 7. printf("Enter a number\n\n"); 8. scanf("%d",&num); 9. if(num==1) 10. { 11. printf("\nThis number is not Prime"); 12. } 13. for(i=2;i<num;i++) 14. { 15. n=num%i; 16. if(n==0) 17. { 18. printf("\nThis number is not Prime\n"); 19. break; 20. } 21. } 22. if(num==i) 23. { 24. printf("\nThis number is prime"); 25. } 26. getch(); 27. }
OUTPUT Enter a number 23 This number is prime

Explanation:-

In this Program, we used some terms that are used in almost every program of C.

Let understand the meaning of these terms.

1.  int num,i,n;

num →

Is a variable of Integer type used to store an integer constant.

i→	Is a variable of Integer type used to store an integer constant.

n →	Is a variable of Integer type used to store an integer constant.

Variable:- An entity (it can be anything which exists in real world) that may vary during program execution is known as variable.
Variable names are the names given to locations in memory.

2.  if(num==1)

        

if() →

If statement is a conditional branching statement. In conditional  branching statement a condition is evaluated.  if(condition)  statement;  If the condition is evaluated and found to be true, the statement  following the "if" is executed. If false, the following statement is  skipped.

== →	It is a relational operator which evaluates the relationship between two  operands and returns "true" or "false"

3. for(i=2;i<num;i++)

for() →

For loop allow us to do the same thing number of times. Therefore, a  starting condition, a final condition and a condition to move on the  next value is given. Its syntax is given as:  for(start value; continue or end condition; increase/decrease value)  statement;

i=2 →

It is a start value.

i<num →

It is a continue or end condition.

i++ →

It is a increase value.

4. n=num%i;

n=num%i →

It divides the num by i and stores the remainder in n.

5. break;

break →

Break statement is used to interrupt the normal flow of program  immediately. It skip statements inside the loop and terminate the loop immediately.