Break the order of numbers when it is 0 using while.

[Bruno Valdeolmillos]

Hello !! I'm trying to do an exercise with 2 whiles that cuts when it is entered and finds out if it's prime or not...the issue is that the cousin thing went ok, now that it doesn't cut...or it enters an infinite loop or short. Does anyone have it clearer? Thanks

[Campbell Ritchie]

Afraid I don't understand the problem. Please explain it so even I can understand it.

[Junilu Lacar]

Bruno Valdeolmillos wrote:Hello !! I'm trying to do an exercise with 2 whiles that cuts when it is entered and finds out if it's prime or not...the issue is that the cousin thing went ok, now that it doesn't cut...or it enters an infinite loop or short. Does anyone have it clearer?

It will probably be easier for people to understand what you're doing if you posted the code you've written so far.

When posting code, please UseCodeTags (←click that, it's a link to instructions on how to use them).

[Bruno Valdeolmillos]

Junilu Lacar wrote:

Bruno Valdeolmillos wrote:Hello !! I'm trying to do an exercise with 2 whiles that cuts when it is entered and finds out if it's prime or not...the issue is that the cousin thing went ok, now that it doesn't cut...or it enters an infinite loop or short. Does anyone have it clearer?

It will probably be easier for people to understand what you're doing if you posted the code you've written so far.

When posting code, please UseCodeTags (←click that, it's a link to instructions on how to use them).

I must make a program that ends when the user enters 0. And that program must find out how many numbers entered are prime using the repetitive while structure.

[Bruno Valdeolmillos]

Junilu Lacar wrote:

Bruno Valdeolmillos wrote:Hello !! I'm trying to do an exercise with 2 whiles that cuts when it is entered and finds out if it's prime or not...the issue is that the cousin thing went ok, now that it doesn't cut...or it enters an infinite loop or short. Does anyone have it clearer?

It will probably be easier for people to understand what you're doing if you posted the code you've written so far.

When posting code, please UseCodeTags (←click that, it's a link to instructions on how to use them).

well i try, i have only in pseudocode.

untitled algorithm
Define co,n1,j,res ,cpri,n2 As Integer
n1=0 ; n2=0 ; j=1 ; res=0;co=0 ; cpr=0

Show "1st lap give me"
read n1


show "give me a number"
read n2

While n1<>0 Do

N1=N1-1

While j<=n2 Do


if n2 MOD j == 0 Then
co=co+1 ; j=j+1

Otherwise
j=j+1

End yes

if co==2 Then
ipr=+1
End yes

if co>2 Then
cpr=0
End yes


EndWhile


EndWhile



EndAlgorithm

[Campbell Ritchie]

Please post that code again with indentation, so we can readily see which endXXX corresponds to which XXX. I think your end yes might be better written as endIf. What happens if you enter negative numbers? How are you trying to find whether a number is prime or not? You do realise that iterating all numbers smaller than the argument is an inefficient way to find prime numbers.

[Junilu Lacar]

Bruno Valdeolmillos wrote:
well i try, i have only in pseudocode.

I'm afraid that's not good enough. You can try implementing your algorithm in Java and show us the code you have. Try to at least get the code you share to compile even if it doesn't entirely work the way you want it to. Nobody here is going to write the code for you though.

[Campbell Ritchie]

I am afraid I think neither code nor pseudocode is going to help us here. I think we need to go back to the logic for thee whole app. Never mind about 0s for now, but tell us how you intend to find out that a number is prime, and also how you intend to show that. No computing words allowed; see this FAQ.

[Bruno Valdeolmillos]

Campbell Ritchie wrote:Please post that code again with indentation, so we can readily see which endXXX corresponds to which XXX. I think your end yes might be better written as endIf. What happens if you enter negative numbers? How are you trying to find whether a number is prime or not? You do realise that iterating all numbers smaller than the as.

Well, I don't want to get into something more difficult, first I would start with positives, if that works well, then expand to negatives.
Step by Step.rgument is an inefficient way to find prime number

[Bruno Valdeolmillos]

Campbell Ritchie wrote:I am afraid I think neither code nor pseudocode is going to help us here. I think we need to go back to the logic for thee whole app. Never mind about 0s for now, but tell us how you intend to find out that a number is prime, and also how you intend to show that. No computing words allowed; see this FAQ.

Well, I tried it in a flowchart, there in theory everything is very beautiful, but in "reality" in a compiler, reality appears there in its maximum expression and it doesn't work.

[Piet Souris]

Bruno Valdeolmillos wrote:(...) Well, I don't want to get into something more difficult, first I would start with positives, if that works well, then expand to negatives.
Step by Step.rgument is an inefficient way to find prime number

A very fast way to determine prime numbers is what is called the 'Sieve of Eratosthenes'. Ever heard of it? Then, having the primes, it should be very easy to count how many primes there are that are smaller than or equal to some inputnumber.

[Campbell Ritchie]

Bruno Valdeolmillos wrote:. . . first I would start with positives . . .

I believe that a prime number is defined as a special case of a natural number, so there would be no such thing as a negative prime number. Nor is 0 a prime number. Nor is 1; the smallest prime number is 2.