C#

static

for

Console.WriteLine

using System;
class Program
{
static void Main()
{
*//*
*// Write prime numbers between 0 and 100.*
*//*
Console.WriteLine(*"--- Primes between 0 and 100 ---"*);
for (int i = 0; i < 100; i++)
{
bool prime = PrimeTool.IsPrime(i);
if (prime)
{
Console.Write(*"Prime: "*);
Console.WriteLine(i);
}
}
*//*
*// Write prime numbers between 10000 and 10100*
*//*
Console.WriteLine(*"--- Primes between 10000 and 10100 ---"*);
for (int i = 10000; i < 10100; i++)
{
if (PrimeTool.IsPrime(i))
{
Console.Write(*"Prime: "*);
Console.WriteLine(i);
}
}
}
}using System;
public static class PrimeTool
{
public static bool IsPrime(int candidate)
{
*// Test whether the parameter is a prime number.*
if ((candidate & 1) == 0)
{
if (candidate == 2)
{
return true;
}
else
{
return false;
}
}
*// Note:*
*// ... This version was changed to test the square.*
*// ... Original version tested against the square root.*
*// ... Also we exclude 1 at the end.*
for (int i = 3; (i * i) <= candidate; i += 2)
{
if ((candidate % i) == 0)
{
return false;
}
}
return candidate != 1;
}
}--- Primes between 0 and 100 ---
Prime: 2
Prime: 3
Prime: 5
Prime: 7
Prime: 11
Prime: 13
Prime: 17
Prime: 19
Prime: 23
Prime: 29
Prime: 31
Prime: 37
Prime: 41
Prime: 43
Prime: 47
Prime: 53
Prime: 59
Prime: 61
Prime: 67
Prime: 71
Prime: 73
Prime: 79
Prime: 83
Prime: 89
Prime: 97
--- Primes between 10000 and 10100 ---
Prime: 10007
Prime: 10009
Prime: 10037
Prime: 10039
Prime: 10061
Prime: 10067
Prime: 10069
Prime: 10079
Prime: 10091
Prime: 10093
Prime: 10099

int Array

public static class PrimeToolHash
{
static int[] primes;
static PrimeToolHash()
{
*//*
*// Initialize array of first primes before methods are called.*
*//*
primes = new int[]
{
3, 7, 11, 17, 23, 29, 37,
47, 59, 71, 89, 107, 131,
163, 197, 239, 293, 353,
431, 521, 631, 761, 919,
1103, 1327, 1597, 1931,
2333, 2801, 3371, 4049,
4861, 5839, 7013, 8419,
10103, 12143, 14591, 17519,
21023, 25229, 30293, 36353,
43627, 52361, 62851, 75431,
90523, 108631, 130363,
156437, 187751, 225307,
270371, 324449, 389357,
467237, 560689, 672827,
807403, 968897, 1162687,
1395263, 1674319, 2009191,
2411033, 2893249, 3471899,
4166287, 4999559, 5999471,
7199369
};
}
public static int GetPrime(int min)
{
*//*
*// Get the first hashtable prime number*
*// ... that is equal to or greater than the parameter.*
*//*
for (int i = 0; i < primes.Length; i++)
{
int num2 = primes[i];
if (num2 >= min)
{
return num2;
}
}
for (int j = min | 1; j < 2147483647; j += 2)
{
if (PrimeTool.IsPrime(j))
{
return j;
}
}
return min;
}
}

Dictionary

private void Initialize(int capacity)
{
int prime = HashHelpers.GetPrime(capacity);
this.buckets = new int[prime];
*// ...*
*// ...*
}

Math.Sqrt

Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.

Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.

This page was last updated on Mar 17, 2023 (edit).