In this post, we will learn how to check the Prime Number using function in C Programming language.
Any whole number which is greater than 1 and has only two factors 1 and itself is known as the Prime Number. For example: 2, 3, 5, 11, 47, . . . so on.
We will check whether the entered number has two or more factors using functions. If the entered number has more than two factors, then it’s not a Prime Number.
So, without further ado, let’s begin the tutorial.
C Program To Check Prime Number Using Function
// C Program To Check Prime Number Using Function
#include <stdio.h>
int checkPrime(int num){
int count = 0;
if (num == 1){
count = 1;
}
for (int i = 2; i <= num / 2; i++){
if (num % i == 0){
count = 1;
break;
}
}
return count;
}
int main(){
int num;
// Asking for Input
printf("Enter a number: ");
scanf("%d", &num);
if (checkPrime(num) == 0){
printf("%d is a Prime Number.", num);
}
else{
printf("%d is not a Prime Number.", num);
}
return 0;
}
Output 1
Enter a number: 17
17 is a Prime Number.Output 2
Enter a number: 91
91 is not a Prime Number.How Does This Program Work ?
int num;In this program, we have declared an int data type variable named num.
// Asking for Input
printf("Enter a number: ");
scanf("%d", &num);Then, the user is asked to enter a number. The value of this number will get stored in the num named variable.
if (checkPrime(num) == 0){
printf("%d is a Prime Number.", num);
}
else{
printf("%d is not a Prime Number.", num);
}Then, we call a custom function named checkPrime which we have declared above. This function will return 0 if the entered number is Prime and 1 if the number is not prime.
If the value of checkPrime(int num) = 0, then the number is a Prime number and we’ll print it.
Otherwise the number is not a Prime Number, and we will print The entered number is not a Prime Number.
int checkPrime(int num){
int count = 0;
if (num == 1){
count = 1;
}
for (int i = 2; i <= num / 2; i++){
if (num % i == 0){
count = 1;
break;
}
}
return count;
}
We have declared a custom function named checkPrime which checks whether the entered number is a Prime Number or Not.
If this function returns 0 as output, then the number is a Prime Number, otherwise the entered number is not a Prime Number.
Conclusion
I hope after going through this post, you understand how to check the Prime number using function in C Programming language.
If you have any doubt regarding the program, feel free to contact us in the comment section. We will be delighted to help you.
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