判断一个数是否为素数的方法

1 static bool prime(int n) 2 { 3 int a = 2; 4 while (a <= n) 5 if ((n % a++) == 0) break; 6 if (a == n + 1 && n != 1) return true; 7 return false; 8 }
调用示例

1 for (int z = 0; z < 100; z++) 2 { 3 if (prime(z)) 4 { 5 Console.Write(z+","); 6 } 7 }
计算1至100素数的和

1 int x = 2; 2 int sum = 0; 3 4 while (x <= 100) 5 { 6 bool f = true; 7 for (int i = 2; i < x; i++) 8 { 9 if (x % i == 0) 10 { 11 f = false; 12 break; 13 } 14 } 15 if (f) 16 { 17 Console.WriteLine("素数:{0}", x); 18 sum += x; 19 } 20 x++; 21 } 22 Console.WriteLine("100以内素数的和是{0}", sum);
//判断素数的其它方法

1 int m, j; 2 for (m = 2; m <= 100; m++) 3 { 4 for (j = 2; j <= m / 2; j++) 5 if (m % j == 0) break; 6 if (j > m / 2) 7 { 8 Console.Write(m + ","); 9 } 10 }