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ublic bool prime(int num)
{
for (int i = 2; i <= (int)Math.Sqrt(num); i++)
{
if (num % i == 0)
return false;
}
return true;
}
public List<Int32> GetPrimersLessThan(Int32 n)
{
Int32 pre = 5;
Int32 cur = 5;
Boolean flag = true; // true +2 false +4
Boolean isPrimer;
List<Int32> list = new List<Int32>();
list.Add(2);
list.Add(3);
list.Add(5);
while (true)
{
isPrimer = true;
if (flag)
{
cur = pre + 2;
}
else
{
cur = pre + 4;
}
if (cur >= n)
break;
for (Int32 i = 0; i < list.Count; i++)
{
if (cur % list[i] == 0)
{
isPrimer = false;
break;
}
}
if (isPrimer)
{
list.Add(cur);
}
pre = cur;
}
return list;
}
using System;
using System.Collections.Generic;
using System.Text;
namespace P52_1
{
class Program
{
static void Main(string[] args)
{
Cal a = new Cal();
a.sushu();
}
}
class Cal
{
private int c=0;
string s;
public int C
{
get
{
return c;
}
set
{
if (value <= 0)
{
Console.WriteLine("请输入正数!");
return;
}
c = value;
}
}
public void sushu()
{
Console.WriteLine("请输入一个正数:");
do
{
s = Console.ReadLine();
try
{
C = Int32.Parse(s);
}
catch (Exception e)
{
Console.WriteLine("请输入数字!");
}
} while (c <= 0);
for (int i = 2; i < C; i++)
{
if (C % i == 0)
{
Console.WriteLine("您输入的正数{0}不是素数,第一个整除的数是{1}", C, i);
return;
}
}
Console.WriteLine("您输入的正数{0}是素数。", C);
}
}
}
public bool prime(int num)
{
for (int i = 2; i < num/2; i++)
{
if (num % i == 0)
return false;
}
return true;
}
class Program
{
static void Main(string[] args)
{
int x;
Console.WriteLine("请输入一个正整数");
x = int.Parse(Console.ReadLine());
if (new isprime().prime(x))
Console.WriteLine("是素数");
else
Console.WriteLine("不是素数");
}
}
public class isprime
{
public bool prime(int num)
{
for(int i = 2; i <= (int)Math.Sqrt(num); i++)
{
if (num % i == 0)
return false;
}
return true;
}
}