C＃|转换类别

Convert类提供了将基本数据类型转换为另一种基本数据类型的不同方法。 Convert类支持的基本类型为Boolean，Char，SByte，Byte，Int16，Int32，Int64，UInt16，UInt32，UInt64，Single，Double，Decimal，DateTime和String。它还提供了支持其他转换的方法。此类在System名称空间下定义。

转换类的特征：

• 它提供了用于将每个基本类型转换为每个其他基本类型的方法。
• 它提供了用于将整数值转换为非十进制字符串表示形式的方法，还可以将表示非十进制数字的字符串转换为整数值。
• 它提供了用于将任何自定义对象转换为任何基本类型的方法。
• 它提供了一组支持base64编码的方法。
• 如果缩小的转换导致数据丢失，则可能发生OverFlowException。

场地：

• DBNull：这是一个常量，表示缺少数据的数据库列，即数据库null。

方法

Method	Description
ChangeType()	It returns an object of a specified type whose value is equivalent to a specified object.
FromBase64CharArray(Char[], Int32, Int32)	Converts a subset of a Unicode character array, which encodes binary data as base-64 digits, to an equivalent 8-bit unsigned integer array. Parameters specify the subset in the input array and the number of elements to convert.
FromBase64String(String)	Converts the specified string, which encodes binary data as base-64 digits, to an equivalent 8-bit unsigned integer array.
GetTypeCode(Object)	Returns the TypeCode for the specified object.
IsDBNull(Object)	Returns an indication whether the specified object is of type DBNull.
ToBase64CharArray()	Converts a subset of an 8-bit unsigned integer array to an equivalent subset of a Unicode character array encoded with base-64 digits.
ToBase64String()	Converts the value of an array of 8-bit unsigned integers to its equivalent string representation that is encoded with base-64 digits.
ToBoolean()	Converts a specified value to an equivalent Boolean value.
ToByte()	Converts a specified value to an 8-bit unsigned integer.
ToChar()	Converts a specified value to a Unicode character.
ToDateTime()	Converts a specified value to a DateTime value.
ToDecimal()	Converts a specified value to a decimal number.
ToDouble()	Converts a specified value to a double-precision floating-point number.
ToInt16()	Converts a specified value to a 16-bit signed integer.
ToInt32()	Converts a specified value to a 32-bit signed integer.
ToInt64()	Converts a specified value to a 64-bit signed integer.
ToSByte()	Converts a specified value to an 8-bit signed integer.
ToSingle()	Converts a specified value to a single-precision floating-point number.
ToUInt16()	Converts a specified value to a 16-bit unsigned integer.
ToUInt32()	Converts a specified value to a 32-bit unsigned integer.
ToUInt64()	Converts a specified value to a 64-bit unsigned integer.

范例1：

// C# program to illustrate the
// use of ToBase64String(Byte[])
// method
using System;
  
class GFG {
  
    // Main method
    static public void Main()
    {
  
        // Creating and initializing 
        // Byte array
        byte[] B = { 2, 4, 8, 16, 32 };
  
        // Display the elements
        Console.WriteLine("BArray is :{0}",
                 BitConverter.ToString(B));
  
        Console.WriteLine();
  
        // Convert the given array
        // into a base 64 string.
        String str = Convert.ToBase64String(B);
  
        // Display the string
        Console.WriteLine("Base 64 string is :{0}", str);
    }
}

输出：

BArray is :02-04-08-10-20

Base 64 string is :AgQIECA=

范例2：

// C# program to illustrate the
// use of ToDecimal(Int16) method
using System;
  
class GFG {
  
    // Main method
    static public void Main()
    {
  
        // Creating and initializing 
        // an array
        short[] ele = {1, Int16.MinValue,
                         -00, 106, -32 };
        decimal sol;
  
        // Display the elements
        Console.WriteLine("Elements are:");
        foreach(short i in ele)
        {
            Console.WriteLine(i);
        }
  
        foreach(short num in ele)
        {
  
            // Convert the given Int16
            // values into decimal values
            // using ToDecimal(Int16) method
            sol = Convert.ToDecimal(num);
  
            // Display the elements
            Console.WriteLine("convert value is: {0}", sol);
        }
    }
}

输出：

Elements are:
1
-32768
0
106
-32
convert value is: 1
convert value is: -32768
convert value is: 0
convert value is: 106
convert value is: -32

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.convert?view=netframework-4.7.2