Add ValueTypeTest

Author: jerviscui

src/Tests/StructTest/Program.cs

@@ -1,15 +1,36 @@
-using StructTest;
+namespace StructTest;
 
-var m1 = new Measurement();
-Console.WriteLine(m1);  // output: NaN (Undefined)
+internal class Program
+{
 
-var m2 = default(Measurement);
-Console.WriteLine(m2);  // output: 0 ()
+    #region Constants & Statics
 
-var ms = new Measurement[2];
-Console.WriteLine(string.Join(", ", ms));  // output: 0 (), 0 ()
+    private static void Main(string[] args)
+    {
+        var m1 = new Measurement();
+        Console.WriteLine(m1);  // output: NaN (Undefined)
 
-ValueTypeTest.ShowSize();
+        var m2 = default(Measurement);
+        Console.WriteLine(m2);  // output: 0 ()
 
-ValueTypeTest.OutOfPrecisionTrueTest();
-ValueTypeTest.OutOfPrecisionFalseTest();
+        var ms = new Measurement[2];
+        Console.WriteLine(string.Join(", ", ms));  // output: 0 (), 0 ()
+
+        ValueTypeTest.ShowSize();
+
+        ValueTypeTest.OutOfPrecisionTrueTest();
+        ValueTypeTest.OutOfPrecisionFalseTest();
+
+        Console.WriteLine();
+        ValueTypeTest.EffectiveLength_4();
+
+        Console.WriteLine();
+        ValueTypeTest.RoundAlgorithm();
+    }
+
+    #endregion
+
+    protected Program()
+    {
+    }
+}

src/Tests/StructTest/ValueTypeTest.cs

@@ -5,6 +5,27 @@ public class ValueTypeTest
 
     #region Constants & Statics
 
+    public static void EffectiveLength_4()
+    {
+        var a = 999999.9999;
+        var b = 999999999.9999;
+        var c = 999999999999.9999;
+        var e = 999999999999999.9999;
+        var f = 999999999999999999.9999;
+
+        var ee = 999999999999999.9999m;
+        var ff = 999999999999999999.9999m;
+
+        Console.WriteLine($"double 6+4 {a}");
+        Console.WriteLine($"double 9+4 {b}");
+        Console.WriteLine($"double 12+4 {c}");
+        Console.WriteLine($"double 15+4 {e}"); // 无效，15 位整数部分 + 4 位小数
+        Console.WriteLine($"double 18+4 {f}"); // 无效，18 位整数部分 + 4 位小数
+
+        Console.WriteLine($"decimal 15+4 {ee}");
+        Console.WriteLine($"decimal 18+4 {ff}");
+    }
+
     public static void OutOfPrecisionFalseTest()
     {
         //（15 - 16 位有效数字）
@@ -19,14 +40,26 @@ public static void OutOfPrecisionFalseTest()
     public static void OutOfPrecisionTrueTest()
     {
         //（15 - 16 位有效数字）
-        var maxValue = 1_999_999_999_999.9999;
-        var beyondMax = 2_000_000_000_000; // 超过 12 位整数部分 + 4 位小数
+        var maxValue = 1_999_999_999_999.9999; // 超过 12 位整数部分 + 4 位小数
+        var beyondMax = 2_000_000_000_000;
 
         Console.WriteLine($"Max value with 4 decimals: {maxValue}");
         Console.WriteLine($"Beyond max value with 4 decimals: {beyondMax}");
         Console.WriteLine($"Are maxValue and beyondMax equal? {maxValue == beyondMax}");
     }
 
+    public static void RoundAlgorithm()
+    {
+        // 银行家舍入法(四舍六入五成双)
+        var rounded = Math.Round(1.235m, 2, MidpointRounding.ToEven);
+
+        // 会计常用舍入(总是远离零)
+        var accountingRound = Math.Round(1.235m, 2, MidpointRounding.AwayFromZero);
+
+        Console.WriteLine(rounded);
+        Console.WriteLine(accountingRound);
+    }
+
     public static void ShowSize()
     {
         Console.WriteLine($"sbyte: Min={sbyte.MinValue}, Max={sbyte.MaxValue}, Size={sizeof(sbyte)} bytes");