C# Random.Next方法代碼示例

Random rnd = new Random();

Console.WriteLine("Generating 10 random numbers:");
                  
for (uint ctr = 1; ctr <= 10; ctr++)
   Console.WriteLine($"{rnd.Next(),15:N0}");

//引入命名空間
using System;

// This derived class converts the uniformly distributed random 
// numbers generated by base.Sample( ) to another distribution.
public class RandomProportional : Random
{
    // The Sample method generates a distribution proportional to the value 
    // of the random numbers, in the range [0.0, 1.0].
    protected override double Sample( )
    {
        return Math.Sqrt( base.Sample( ) );
    }
   
    public override int Next()
    {
       return (int) (Sample() * int.MaxValue);
    }   
}

public class RandomSampleDemo  
{
    static void Main( )
    {	
        const int rows = 4, cols = 6;
        const int runCount = 1000000;
        const int distGroupCount = 10;
        const double intGroupSize = 
            ( (double)int.MaxValue + 1.0 ) / (double)distGroupCount;

        RandomProportional randObj = new RandomProportional( );

        int[ ]      intCounts = new int[ distGroupCount ];
        int[ ]      realCounts = new int[ distGroupCount ];

        Console.WriteLine( 
            "\nThe derived RandomProportional class overrides " +
            "the Sample method to \ngenerate random numbers " +
            "in the range [0.0, 1.0]. The distribution \nof " +
            "the numbers is proportional to their numeric values. " +
            "For example, \nnumbers are generated in the " +
            "vicinity of 0.75 with three times the \n" +
            "probability of those generated near 0.25." );
        Console.WriteLine( 
            "\nRandom doubles generated with the NextDouble( ) " +
            "method:\n" );

        // Generate and display [rows * cols] random doubles.
        for( int i = 0; i < rows; i++ )
        {
            for( int j = 0; j < cols; j++ )
                Console.Write( "{0,12:F8}", randObj.NextDouble( ) );
            Console.WriteLine( );
        }

        Console.WriteLine( 
            "\nRandom integers generated with the Next( ) " +
            "method:\n" );

        // Generate and display [rows * cols] random integers.
        for( int i = 0; i < rows; i++ )
        {
            for( int j = 0; j < cols; j++ )
                Console.Write( "{0,12}", randObj.Next( ) );
            Console.WriteLine( );
        }

        Console.WriteLine( 
            "\nTo demonstrate the proportional distribution, " +
            "{0:N0} random \nintegers and doubles are grouped " +
            "into {1} equal value ranges. This \n" +
            "is the count of values in each range:\n",
            runCount, distGroupCount );
        Console.WriteLine( 
            "{0,21}{1,10}{2,20}{3,10}", "Integer Range",
            "Count", "Double Range", "Count" );
        Console.WriteLine( 
            "{0,21}{1,10}{2,20}{3,10}", "-------------",
            "-----", "------------", "-----" );

        // Generate random integers and doubles, and then count 
        // them by group.
        for( int i = 0; i < runCount; i++ )
        {
            intCounts[ (int)( (double)randObj.Next( ) / 
                intGroupSize ) ]++;
            realCounts[ (int)( randObj.NextDouble( ) * 
                (double)distGroupCount ) ]++;
        }

        // Display the count of each group.
        for( int i = 0; i < distGroupCount; i++ )
            Console.WriteLine( 
                "{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}",
                (int)( (double)i * intGroupSize ),
                (int)( (double)( i + 1 ) * intGroupSize - 1.0 ),
                intCounts[ i ],
                ( (double)i ) / (double)distGroupCount,
                ( (double)( i + 1 ) ) / (double)distGroupCount,
                realCounts[ i ] );
    }
}

Console.WriteLine(                 
    "This example of the Random.Next( ) methods\n" +
    "generates the following output.\n" );
Console.WriteLine(                 
    "Create Random objects all with the same seed and " +
    "generate\nsequences of numbers with different " +
    "bounds. Note the effect\nthat the various " +
    "combinations of bounds have on the sequences." );

NoBoundsRandoms( 234 );

UpperBoundRandoms( 234, Int32.MaxValue );
UpperBoundRandoms( 234, 2000000000 );
UpperBoundRandoms( 234, 200000000 );

BothBoundsRandoms( 234, 0, Int32.MaxValue );
BothBoundsRandoms( 234, Int32.MinValue, Int32.MaxValue );
BothBoundsRandoms( 234, -2000000000, 2000000000 );
BothBoundsRandoms( 234, -200000000, 200000000 );
BothBoundsRandoms( 234, -2000, 2000 );

// Generate random numbers with no bounds specified.
void NoBoundsRandoms( int seed )
{
    Console.WriteLine( 
        "\nRandom object, seed = {0}, no bounds:", seed );
    Random randObj = new Random( seed );

    // Generate six random integers from 0 to int.MaxValue.
    for( int j = 0; j < 6; j++ )
        Console.Write( "{0,11} ", randObj.Next( ) );
    Console.WriteLine( );
}

// Generate random numbers with an upper bound specified.
void UpperBoundRandoms( int seed, int upper )
{
    Console.WriteLine( 
        "\nRandom object, seed = {0}, upper bound = {1}:", 
        seed, upper );
    Random randObj = new Random( seed );

    // Generate six random integers from 0 to the upper bound.
    for( int j = 0; j < 6; j++ )
        Console.Write( "{0,11} ", randObj.Next( upper ) );
    Console.WriteLine( );
}

// Generate random numbers with both bounds specified.
void BothBoundsRandoms( int seed, int lower, int upper )
{
    Console.WriteLine( 
        "\nRandom object, seed = {0}, lower = {1}, " +
        "upper = {2}:", seed, lower, upper );
    Random randObj = new Random( seed );

    // Generate six random integers from the lower to 
    // upper bounds.
    for( int j = 0; j < 6; j++ )
        Console.Write( "{0,11} ", 
            randObj.Next( lower, upper) );
    Console.WriteLine( );
}

Random rnd = new Random();
string[] malePetNames = { "Rufus", "Bear", "Dakota", "Fido", 
                          "Vanya", "Samuel", "Koani", "Volodya", 
                          "Prince", "Yiska" };
string[] femalePetNames = { "Maggie", "Penny", "Saya", "Princess", 
                            "Abby", "Laila", "Sadie", "Olivia", 
                            "Starlight", "Talla" };                                      

// Generate random indexes for pet names.
int mIndex = rnd.Next(malePetNames.Length);
int fIndex = rnd.Next(femalePetNames.Length);

// Display the result.
Console.WriteLine("Suggested pet name of the day: ");
Console.WriteLine("   For a male:     {0}", malePetNames[mIndex]);
Console.WriteLine("   For a female:   {0}", femalePetNames[fIndex]);

Random rnd = new Random();

Console.WriteLine("\n20 random integers from -100 to 100:");
for (int ctr = 1; ctr <= 20; ctr++) 
{
   Console.Write("{0,6}", rnd.Next(-100, 101));
   if (ctr % 5 == 0) Console.WriteLine();
}

Console.WriteLine("\n20 random integers from 1000 to 10000:");      
for (int ctr = 1; ctr <= 20; ctr++) 
{
   Console.Write("{0,8}", rnd.Next(1000, 10001));
   if (ctr % 5 == 0) Console.WriteLine();
}

Console.WriteLine("\n20 random integers from 1 to 10:");
for (int ctr = 1; ctr <= 20; ctr++) 
{
   Console.Write("{0,6}", rnd.Next(1, 11));
   if (ctr % 5 == 0) Console.WriteLine();
}

Random rnd = new Random();
string[] malePetNames = { "Rufus", "Bear", "Dakota", "Fido", 
                          "Vanya", "Samuel", "Koani", "Volodya", 
                          "Prince", "Yiska" };
string[] femalePetNames = { "Maggie", "Penny", "Saya", "Princess", 
                            "Abby", "Laila", "Sadie", "Olivia", 
                            "Starlight", "Talla" };                                      

// Generate random indexes for pet names.
int mIndex = rnd.Next(0, malePetNames.Length);
int fIndex = rnd.Next(0, femalePetNames.Length);

// Display the result.
Console.WriteLine("Suggested pet name of the day: ");
Console.WriteLine("   For a male:     {0}", malePetNames[mIndex]);
Console.WriteLine("   For a female:   {0}", femalePetNames[fIndex]);

//引入命名空間
using System;

class CondOpApp {
    [STAThread]
    static void Main(string[] args) {
        Random rand = new Random();
        int a = 0, b = 0;

        for (int i = 0; i < 5; i++) {
            a = rand.Next() % 100;
            b = rand.Next() % 100;

            Console.WriteLine("a={0}, b={1}, so the winner is: {2}", a, b, a > b ? 'a' : 'b');
        }
    }
}

//引入命名空間
using System;

public class RandomIntegers
{
   public static void Main( string[] args )
   {
      Random randomNumbers = new Random(); 
      int face; 

      for ( int counter = 1; counter <= 20; counter++ )
      {
         face = randomNumbers.Next( 1, 7 );
         Console.Write( "{0}  ", face );
         if ( counter % 5 == 0 )
            Console.WriteLine();
      } 
   }
}