12,897,830 members (69,493 online)
Rate this:
See more:
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

Rate this:

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.

Top Experts
Last 24hrsThis month
 OriginalGriff 275 Maciej Los 90 CHill60 90 ppolymorphe 60 Dave Kreskowiak 50
 OriginalGriff 5,612 CHill60 3,713 Jochen Arndt 2,958 Karthik Bangalore 2,456 ppolymorphe 2,435

Web02 | 2.8.170424.1 | Last Updated 9 Nov 2012