F# Snippets for System.Random

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Ctor/FS/RandomCtor.fsproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="ctor.fs" />
+    <Compile Include="ctor1.fs" />
+    <Compile Include="ctor4.fs" />
+  </ItemGroup>
+
+</Project>

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Ctor/FS/ctor.fs

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+module Ctor
+
+//<Snippet1>
+// Example of the Random class constructors and Random.NextDouble()
+// method.
+open System
+open System.Threading
+
+// Generate random numbers from the specified Random object.
+let runIntNDoubleRandoms (randObj: Random) =
+    // Generate the first six random integers.
+    for _ = 1 to 6 do
+        printf $" {randObj.Next(),10} "
+    printfn ""
+
+    // Generate the first six random doubles.
+    for _ = 1 to 6 do
+        printf $" {randObj.NextDouble():F8} "
+    printfn ""
+
+let fixedSeedRandoms seed =
+    printfn $"\nRandom numbers from a Random object with seed = %i{seed}:"
+    let fixRand = Random seed
+
+    runIntNDoubleRandoms fixRand
+
+let autoSeedRandoms () =
+    // Wait to allow the timer to advance.
+    Thread.Sleep 1
+
+    printfn "\nRandom numbers from a Random object with an auto-generated seed: "
+    let autoRand = Random ()
+
+    runIntNDoubleRandoms autoRand
+
+printfn 
+  """This example of the Random class constructors and Random.NextDouble()
+generates the following output.
+Create Random objects, and then generate and display six integers and
+six doubles from each."""
+
+fixedSeedRandoms 123
+fixedSeedRandoms 123
+
+fixedSeedRandoms 456
+fixedSeedRandoms 456
+
+autoSeedRandoms ()
+autoSeedRandoms ()
+autoSeedRandoms ()
+
+(*
+This example of the Random class constructors and Random.NextDouble()
+generates an output similar to the following:
+
+Create Random objects, and then generate and display six integers and
+six doubles from each.
+
+Random numbers from a Random object with seed = 123:
+ 2114319875  1949518561  1596751841  1742987178  1586516133   103755708
+ 0.01700087  0.14935942  0.19470390  0.63008947  0.90976122  0.49519146
+
+Random numbers from a Random object with seed = 123:
+ 2114319875  1949518561  1596751841  1742987178  1586516133   103755708
+ 0.01700087  0.14935942  0.19470390  0.63008947  0.90976122  0.49519146
+
+Random numbers from a Random object with seed = 456:
+ 2044805024  1323311594  1087799997  1907260840   179380355   120870348
+ 0.21988117  0.21026556  0.39236514  0.42420498  0.24102703  0.47310170
+
+Random numbers from a Random object with seed = 456:
+ 2044805024  1323311594  1087799997  1907260840   179380355   120870348
+ 0.21988117  0.21026556  0.39236514  0.42420498  0.24102703  0.47310170
+
+Random numbers from a Random object with an auto-generated seed:
+  380213349   127379247  1969091178  1983029819  1963098450  1648433124
+ 0.08824121  0.41249688  0.36445811  0.05637512  0.62702451  0.49595560
+
+Random numbers from a Random object with an auto-generated seed:
+  861793304  2133528783  1947358439   124230908   921262645  1087892791
+ 0.56880819  0.42934091  0.60162512  0.74388610  0.99432979  0.30310005
+
+Random numbers from a Random object with an auto-generated seed:
+ 1343373259  1992194672  1925625700   412915644  2026910487   527352458
+ 0.04937517  0.44618494  0.83879212  0.43139707  0.36163507  0.11024451
+*)
+//</Snippet1>
+
+// Code added to show how to initialize Random objects with the
+// same timer value that will produce unique random number sequences.
+let createEngineWithSameTimer () =
+// <Snippet3>
+    let randomEngines = 
+        [| for i in 0 .. 3 -> Random(int (DateTime.Now.Ticks >>> i)) |]
+// </Snippet3>
+    for i in randomEngines do
+        printfn "%i" (i.Next())

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Ctor/FS/ctor1.fs

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+module Ctor1
+
+// <Snippet2>
+open System
+open System.Threading
+
+let showRandomNumbers (rand: Random) =
+    printfn ""
+    let values = Array.zeroCreate 5
+    rand.NextBytes values
+    for value in values do 
+        printf "%5i" value
+    printfn ""
+
+let rand1 = Random()
+let rand2 = Random()
+Thread.Sleep 2000
+let rand3 = Random()
+
+showRandomNumbers rand1
+showRandomNumbers rand2
+showRandomNumbers rand3
+
+// The example displays an output similar to the following:
+//       28   35  133  224   58
+//
+//       28   35  133  224   58
+//
+//       32  222   43  251   49
+// </Snippet2>

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Ctor/FS/ctor4.fs

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+module Ctor4
+
+// <Snippet4>
+open System
+open System.Threading
+
+let showRandomNumbers (rand: Random) =
+    printfn ""
+    let values = Array.zeroCreate 5
+    rand.NextBytes values
+    for value in values do 
+        printf "%5i" value
+    printfn ""
+
+let rand1 = Random(DateTime.Now.Ticks &&& 0x0000FFFFL |> int)
+let rand2 = Random(DateTime.Now.Ticks &&& 0x0000FFFFL |> int)
+Thread.Sleep 20
+let rand3 = Random(DateTime.Now.Ticks &&& 0x0000FFFFL |> int)
+
+showRandomNumbers rand1
+showRandomNumbers rand2
+showRandomNumbers rand3
+
+// The example displays output similar to the following:
+//   145  214  177  134  173
+//
+//   145  214  177  134  173
+//
+//   126  185  175  249  157
+// </Snippet4>

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Next/FS/Next2.fs

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+module Next2
+
+open System
+
+//<Snippet2>
+let rnd = Random()
+
+printfn "\n20 random integers from -100 to 100:"
+for i = 1 to 20 do 
+    printf "%6i" (rnd.Next(-100,100))
+    if i % 5 = 0 then printfn ""
+
+printfn "\n20 random integers from 1000 to 10000:"
+for i = 1 to 20 do 
+    printf "%8i" (rnd.Next(1000,10001))
+    if i % 5 = 0 then printfn ""
+
+printfn "\n20 random integers from 1 to 10:"
+for i = 1 to 20 do 
+    printf "%6i" (rnd.Next(1,11))
+    if i % 5 = 0 then printfn ""
+
+// The example displays output similar to the following:
+//       20 random integers from -100 to 100:
+//           65   -95   -10    90   -35
+//          -83   -16   -15   -19    41
+//          -67   -93    40    12    62
+//          -80   -95    67   -81   -21
+//
+//       20 random integers from 1000 to 10000:
+//           4857    9897    4405    6606    1277
+//           9238    9113    5151    8710    1187
+//           2728    9746    1719    3837    3736
+//           8191    6819    4923    2416    3028
+//
+//       20 random integers from 1 to 10:
+//            9     8     5     9     9
+//            9     1     2     3     8
+//            1     4     8    10     5
+//            9     7     9    10     5
+// </Snippet2>

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Next/FS/RandomNext.fsproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="next.fs" />
+    <Compile Include="next1.fs" />
+    <Compile Include="Next2.fs" />
+    <Compile Include="next3.fs" />
+    <Compile Include="next4.fs" />
+  </ItemGroup>
+
+</Project>

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Next/FS/next.fs

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+module Next
+
+// Example of the Random.Next() methods.
+open System
+
+//<Snippet1>
+let noBoundsRandoms seed =
+    printfn "\nRandom object, seed = %i, no bounds:" seed
+    let randObj = Random seed
+
+    // Generate six random integers from 0 to int.MaxValue.
+    for _ = 1 to 6 do
+        printf "%11i " (randObj.Next())
+    printfn ""
+
+// Generate random numbers with an upper bound specified.
+let upperBoundRandoms seed upper = 
+    printfn "\nRandom object, seed = %i, upper bound = %i" seed upper
+    let randObj = Random seed
+
+    // Generate six random integers from 0 to the upper bound.
+    for _ = 1 to 6 do
+        printf "%11i " (randObj.Next(upper))
+    printfn ""
+
+// Generate random numbers with both bounds specified.
+let bothBoundRandoms seed lower upper =
+    printfn "\nRandom object, seed = %i, lower = %i, upper = %i: " seed lower upper
+    let randObj = Random seed
+
+    // Generate six random integers from the lower to upper bounds.
+    for _ = 1 to 6 do 
+        printf "%11i " (randObj.Next(lower,upper))
+    printfn ""
+
+printfn "This example of the Random.Next() methods\ngenerates the following.\n"
+
+printfn """Create Random objects all with the same seed and generate
+sequences of numbers with different bounds. Note the effect
+that the various combinations of bounds have on the sequences."""
+
+noBoundsRandoms 234
+
+upperBoundRandoms 234 Int32.MaxValue
+upperBoundRandoms 234 2000000000
+upperBoundRandoms 234 200000000
+
+bothBoundRandoms 234 0 Int32.MaxValue
+bothBoundRandoms 234 Int32.MinValue Int32.MaxValue
+bothBoundRandoms 234 -2000000000 2000000000
+bothBoundRandoms 234 -200000000 200000000
+bothBoundRandoms 234 -2000 2000
+
+(*
+This example of the Random.Next() methods
+generates the following output.
+
+Create Random objects all with the same seed and generate
+sequences of numbers with different bounds. Note the effect
+that the various combinations of bounds have on the sequences.
+
+Random object, seed = 234, no bounds:
+2091148258  1024955023   711273344  1081917183  1833298756   109460588
+
+Random object, seed = 234, upper bound = 2147483647:
+2091148258  1024955023   711273344  1081917183  1833298756   109460588
+
+Random object, seed = 234, upper bound = 2000000000:
+1947533580   954563751   662424922  1007613896  1707392518   101943116
+
+Random object, seed = 234, upper bound = 200000000:
+194753358    95456375    66242492   100761389   170739251    10194311
+
+Random object, seed = 234, lower = 0, upper = 2147483647:
+2091148258  1024955023   711273344  1081917183  1833298756   109460588
+
+Random object, seed = 234, lower = -2147483648, upper = 2147483647:
+2034812868   -97573602  -724936960    16350718  1519113864 -1928562472
+
+Random object, seed = 234, lower = -2000000000, upper = 2000000000:
+1895067160   -90872498  -675150156    15227793  1414785036 -1796113767
+
+Random object, seed = 234, lower = -200000000, upper = 200000000:
+189506716    -9087250   -67515016     1522779   141478503  -179611377
+
+Random object, seed = 234, lower = -2000, upper = 2000:
+    1895         -91        -676          15        1414       -1797
+*)
+//</Snippet1>

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Next/FS/next1.fs

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+module Next1
+
+open System
+
+// <Snippet3>
+let rnd = Random()
+
+let malePetNames =
+    [| "Rufus"; "Bear"; "Dakota"; "Fido";
+        "Vanya"; "Samuel"; "Koani"; "Volodya";
+        "Prince"; "Yiska" |]
+let femalePetNames = 
+    [| "Maggie"; "Penny"; "Saya"; "Princess";
+        "Abby"; "Laila"; "Sadie"; "Olivia";
+        "Starlight"; "Talla" |]
+
+// Generate random indexes for pet names.
+let mIndex = rnd.Next malePetNames.Length
+let fIndex = rnd.Next femalePetNames.Length
+
+// Display the result.
+printfn "Suggested pet name of the day: "
+printfn "   For a male:     %s" malePetNames.[mIndex]
+printfn "   For a female:   %s" femalePetNames.[fIndex]
+
+// The example displays output similar to the following:
+//       Suggested pet name of the day:
+//          For a male:     Koani
+//          For a female:   Maggie
+// </Snippet3>

samples/snippets/fsharp/VS_Snippets_CLR_System/system.Random.Next/FS/next3.fs

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+module Next3
+
+open System
+
+// <Snippet5>
+let rnd = Random()
+
+printfn "Generating 10 random numbers:"
+
+for _ = 1 to 10 do
+    printfn $"{rnd.Next(),15:N0}"
+
+// The example displays output like the following:
+//
+//     Generating 10 random numbers:
+//         1,733,189,596
+//           566,518,090
+//         1,166,108,546
+//         1,931,426,514
+//         1,532,939,448
+//           762,207,767
+//           815,074,920
+//         1,521,208,785
+//         1,950,436,671
+//         1,266,596,666
+// </Snippet5>