.NET 4.0 的BigInteger和Complex类

分手后的思念是犯贱 2022-01-06 16:57 112阅读 0赞

.NET4.0 Beta2中提供了新的System.Numerics命名空间，对应于System.Numerics.dll。该命名空间下就两个类BigInteger和Complex，我们来简单了解下  
这两个类的用法。

**BigInteger：任意大小的带符号整数,可以表示任意大小的整数**

1.[Int64][], [SByte][], [UInt16][], [UInt32][], and [UInt64][]这些都有一个MinValue和MaxValue属性。而BigInteger没有这两个属性，因为它没有大小限制。  
2.不可变的类型.  
3.由于他没有大小限制，理论上当它足够大的时候会出现[OutOfMemoryException][]异常.

**BigInteger初始化**

1.我们可以使用已有的数据类型来初始化BigInteger，如下：

BigInteger bigIntFromDouble = new BigInteger(179032.6541);//会截取小点前的
    BigInteger bigIntFromInt64 = new BigInteger(934157136952);

2.我们也可以使用超出现有数据类型范围的方式来得到BigInteger：

byte[] bytes = { 5, 4, 3, 2, 1 };
    BigInteger number = new BigInteger(bytes);
    Console.WriteLine("The value of number is {0} (or 0x{0:x}).", number); 
    //The value of number is 4328719365 (or 0x102030405).   
    字节数组的第一个元素为16进制的最低位，依次升高.

3.可以使用[Parse][]或 [TryParse][]方法将string的实例化为BigInteger：

string positiveString = "91389681247993671255432112000000";
    string negativeString = "-90315837410896312071002088037140000";
    BigInteger posBigInt = 0;
    BigInteger negBigInt = 0;
    
    posBigInt = BigInteger.Parse(positiveString);
    Console.WriteLine(posBigInt);
    
    BigInteger.TryParse(negativeString, out negBigInt);
    Console.WriteLine(negBigInt);

4. 还可以使用静态方法Pow如下：

BigInteger number = BigInteger.Pow(Int64.MaxValue, 3);

BigInteger支持所有的数学运算，我们可以完全象使用其他整数类型一样使用BigInteger

**Complex复数类**

1.var z1 = new Complex(); // this creates complex zero (0, 0)
      var z2 = new Complex(2, 4);
    var z3 = new Complex(3, 5);
    
    Console.WriteLine("Complex zero: " + z1);
    Console.WriteLine(z2 + " + " + z3 + " = " + (z2 + z3));
    
    Console.WriteLine("|z2| = " + z2.Magnitude);
    Console.WriteLine("Phase of z2 = " + z2.Phase);

2.我们可以使用一个ComplexFormatter类来辅助我们做格式化输出，如下：

using System;
    using System.Numerics;
    
    public class ComplexFormatter :IFormatProvider, ICustomFormatter
    {
       
    public object GetFormat(Type formatType) 
       {   
    if (formatType == typeof(ICustomFormatter))
    return this;
    else
             return null;
       }
    
    public string Format(string format, object arg, 
    IFormatProvider provider)
       {
       
    if (arg is Complex)
          {
       
    Complex c1 = (Complex) arg; 
    // Check if the format string has a precision specifier.
    int precision;
    string fmtString = String.Empty;
    if (format.Length > 1) {
       
    try {
       
                   precision = Int32.Parse(format.Substring(1));
                }
    catch (FormatException) {
       
                   precision = 0;
                }
                fmtString = "N" + precision.ToString();
             }
    if (format.Substring(0, 1).Equals("I", StringComparison.OrdinalIgnoreCase))
    return c1.Real.ToString("N2") + " + " + c1.Imaginary.ToString("N2") + "i";
    else if (format.Substring(0, 1).Equals("J", StringComparison.OrdinalIgnoreCase))
    return c1.Real.ToString("N2") + " + " + c1.Imaginary.ToString("N2") + "j";
    else
                return c1.ToString(format, provider);
          }
    else
    {
       
    if (arg is IFormattable)
    return ((IFormattable) arg).ToString(format, provider);
    else if (arg != null) 
    return arg.ToString();
    else
                return String.Empty;
          }                        
       }
    }

3.使用如下：

Complex c1 = new Complex(12.1, 15.4);
    Console.WriteLine("Formatting with ToString():" + c1.ToString());
    Console.WriteLine("Formatting with ToString(format): " +  c1.ToString("N2"));
    Console.WriteLine("Custom formatting with I0:" +  String.Format(new ComplexFormatter(), "{0:I0}", c1));
    Console.WriteLine("Custom formatting with J3:" +  String.Format(new ComplexFormatter(), "{0:J3}", c1));

转载于:https://www.cnblogs.com/eagle1986/archive/2012/01/16/2323570.html

[Int64]: http://msdn.microsoft.com/en-us/library/system.int64%28VS.100%29.aspx
[SByte]: http://msdn.microsoft.com/en-us/library/system.sbyte%28VS.100%29.aspx
[UInt16]: http://msdn.microsoft.com/en-us/library/system.uint16%28VS.100%29.aspx
[UInt32]: http://msdn.microsoft.com/en-us/library/system.uint32%28VS.100%29.aspx
[UInt64]: http://msdn.microsoft.com/en-us/library/system.uint64%28VS.100%29.aspx
[OutOfMemoryException]: http://msdn.microsoft.com/en-us/library/system.outofmemoryexception%28VS.100%29.aspx
[Parse]: http://msdn.microsoft.com/en-us/library/system.numerics.biginteger.parse%28VS.100%29.aspx
[TryParse]: http://msdn.microsoft.com/en-us/library/system.numerics.biginteger.tryparse%28VS.100%29.aspx