i need help how can i program a code in C language that if the user inputs a number it will check if thenumber is prime or not

Question

without using for loop.. only if else statements

Answer 1

Cjay Medallo , yes, your code looks good now. All we have to do is convert the following for loop into a while loop

for(i = 2; i <= n/2; ++i) {
if(n%i == 0) {
num = 1;
break;
}
}

Well, that's not too hard. It has three parts:
1. An initialization (i=2), which happens only ONCE at the beginning,
2. a test condition (i<=n/2), which is checked at the beginning of each loop, and
3. an update statement (++i) executed at the end of each loop.

We can take care of #2 with while (i<=n/2), but the rest we'd have to put at appropriate places ourselves. But that's not hard at all if you know what they do: #1 goes right before the while loop, and #3 goes right at the end (but inside) of the loop. So it'd look like

i = 2;
while (i <= n/2) {
if(n%i == 0) {
num = 1;
break;
}
++i;
}

Does that make sense? If you understand this you'd be able to convert any for loop in C into a while loop.

Answer 2

alpha5and5 Most welcome ^_^ , fixed the bug check it now .

Answer 3

https://code.sololearn.com/chDtCd6ZOwZH/?ref=app

alpha5and5 here's you corrected recursive code

Answer 4

Well, can you write the code using for loop, save it in the code playground, and share a link? Then I can help you convert it into a while loop version.

Answer 5

Is while loop allowed? Or recursion? Otherwise I don't see a good way to do it.

Answer 6

It has the correct logic, but you need to print if it is a prime or not. Can you not finish the code?

Answer 7

alpha5and5 please make a separate post in the Q&A section, and I'm sure someone will help you out!

Answer 8

It looks good, but you seen to have accidentally written the same code segment twice. First from lines 5-12, and then again from 13-20. Just using that once should be enough.

Answer 9

yeah one is enough sorry.. because when i code it using that the number 1 print f can't execute.. i don't understand that's why i write it twice then it works.. sorry for the hassle bro.. thank you so much i appreciate your effort

Answer 10

You're welcome! 😊

I'm not sure what happened before, but it looks like it's working now, even with 1, right?

Answer 11

yep it's perfectly fine now.. again thanks for the help Kishalaya Saha

Answer 12

yeah only for loop.. is not allowed pls help i need to understand it

Answer 13

https://code.sololearn.com/cKSS3SiyU9kT/?ref=app

Answer 14

that is all i can do.. im new.. i need some expert to check if it's right or not

Answer 15

alpha5and5 your code isn't correct. It says 7 is not a prime. The scanf part was correct in the original code. And the use of break was also a great idea.

And please, let the original poster finish their code. Thanks!

Answer 16

is it printf("Prime number");
if and then else.. i don't know sorry.. im new so pls help

Answer 17

Kishalaya Saha

Answer 18

i see.. i'm also new in C .. i focused in web dev.. i will try my best to finish this thank you all

Answer 19

i think it's right.. pls check.. the problem is we are not allowed to use for loop.. maybe there is a way to code it without using for loop so pls help me

Answer 20

Kishalaya Saha