Click here to Skip to main content
12,503,947 members (56,869 online)
Rate this:
 
Please Sign up or sign in to vote.
See more: C++ C
I can write the code for "Sieve of Eratosthenes" to generate all the prime number up to n. But I want to write a program that will generate and index all the prime number (up to n) into an array, than check whether a number is prime or not. Can anyone please help me to do it?

For Example: if n = 10, than the prime number is 2 3 5 7. Index them into an array a[ ] = {2, 3, 4, 7}. Than write a program and press a number as input from keyboard, than check the number is prime or not. I know that there is a simple way to check whether a number is prime or not but I want to do it by the above way. How can I do that???
Posted 9-Nov-12 1:44am
Updated 9-Nov-12 1:46am
v3

1 solution

Rate this: bad
 
good
Please Sign up or sign in to vote.

Solution 1

Since you mark all numbers in your original code as prime or not, you should already have a lookup table which you can use.

Alternatively you could create an array or use a simple vector[^] or list[^] to store them. Then when the user enters a value you can look it up in the container and report accordingly.

Sieve of Eratosthenes in C#[^] is a sample article that should help.
  Permalink  

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

  Print Answers RSS
Top Experts
Last 24hrsThis month


Advertise | Privacy | Mobile
Web02 | 2.8.160919.1 | Last Updated 9 Nov 2012
Copyright © CodeProject, 1999-2016
All Rights Reserved. Terms of Service
Layout: fixed | fluid

CodeProject, 503-250 Ferrand Drive Toronto Ontario, M3C 3G8 Canada +1 416-849-8900 x 100