素数探すソース(てきとー)

Program.cs

using System;

namespace PrimeFind {
    class Program {
        static void Main(string[] args) {

            int[] prime = FindPrimeNumber(1000);
            foreach (int i in prime) {
                Console.Out.Write("{0},",i);
            }

        }

        static int[] FindPrimeNumber(int maxNumber) {
            bool[] frags = new bool[maxNumber];
            frags[0] = true;// 1は素数じゃなかった気がする
            for (int i = 1;i <= maxNumber;i++) {
                if (frags[i-1] == false) {//indexをずらしてフラグ検証
                    int n=1;
                    while (true) {//素数の倍数は素数じゃない
                        n++;
                        if (i * n > maxNumber) {
                            break;
                        }
                        frags[(i*n)-1]=true;
                    }
                }
            }
            int size = 0;
            foreach (bool b in frags) {
                if (b == false) {
                    size++;
                }
            }
            int[] result = new int[size];
            int index = 0;
            for (int i = 0;i < frags.Length;i++) {
                if (frags[i] == false) {
                    result[index] = i+1;//indexずらしてたので
                    index++;
                }
            }
            return result;
        } 
    }
}

result.txt

2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,1
07,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,2
23,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,3
37,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,4
57,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,5
93,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,7
19,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,829,839,853,8
57,859,863,877,881,883,887,907,911,919,929,937,941,947,953,967,971,977,983,991,9
97,続行するには何かキーを押してください . . .