此方法用于将8位无符号整数数组的子集转换为以64位为基数编码的Unicode字符数组的等效子集。参数将子集指定为输入和输出数组中的偏移量，以及输入数组中要转换的元素数。
句法：
public static int ToBase64CharArray (byte[] inArray, int offsetIn, int length, char[] outArray, int offsetOut);
参数：
- inArray ：一个8位无符号整数的输入数组。
- offsetIn ： inArray中的位置。
- length ：要转换的inArray的元素数。
- outArray ：Unicode字符的输出数组。
- offsetOut ： outArray中的位置。
返回值：该方法返回一个32位带符号整数，其中包含outArray中的字节数。
例外情况：
- ArgumentNullException ：如果inArray或outArray为null。
- ArgumentOutOfRangeException ：如果offsetIn ， offsetOut或length为负数，或者offsetIn加上length大于inArray的长度，或者offsetOut加上要返回的元素数大于outArray的长度。
下面的程序说明了Convert.ToBase64CharArray()方法的用法：
范例1：
// C# program to demonstrate the
// Convert.FromBase64String(String)
// Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// defining and initializing
// byte1 and byte2
byte[] byte1 = {2, 4, 6, 8, 10, 12,
14, 16, 18, 20};
byte[] byte2 = {10, 20, 30, 40, 50};
// calling get() Method
get(byte1, "byte1");
Console.WriteLine("");
get(byte2, "byte2");
}
catch (ArgumentNullException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
catch (ArgumentOutOfRangeException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(),
e.Message);
}
}
// Defining get() method
public static void get(byte[] bytes, string str)
{
Console.WriteLine("For {0}", str);
long arrayLength = (long)((4.0d / 3.0d) *
bytes.Length);
// If array length is not divisible
// by 4, go up to the next multiple
// of 4.
if (arrayLength % 4 != 0)
arrayLength += 4 - arrayLength % 4;
// creating object of char array
char[] base64CharArray = new char[arrayLength];
// converting byte to base 64 string
int val = Convert.ToBase64CharArray(bytes, 0,
bytes.Length, base64CharArray, 0);
Console.WriteLine("Total no of bytes: {0}", val);
// display the base64CharArray
Console.Write("base64CharArray: ");
for (int j = 0; j < base64CharArray.Length; j++)
Console.Write("{0}", base64CharArray[j]);
Console.WriteLine("");
}
}
输出：
For byte1
Total no of bytes: 16
base64CharArray: AgQGCAoMDhASFA==
For byte2
Total no of bytes: 8
base64CharArray: ChQeKDI=
示例2：对于ArgumentNullException
// C# program to demonstrate the
// Convert.FromBase64String(String)
// Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// defining and initializing
// byte1
byte[] byte1 = {2, 4, 6, 8, 10, 12,
14, 16, 18, 20};
// calling get() Method
get(byte1, "byte1");
// converting base 64
// string to byte array
Console.WriteLine("inArray and outArray are null.");
int val = Convert.ToBase64CharArray(null, 0,
10, null, 0);
Console.WriteLine("Converted byte value: {0}", val);
}
catch (ArgumentNullException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
catch (ArgumentOutOfRangeException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(),
e.Message);
}
}
// Defining get() method
public static void get(byte[] bytes, string str)
{
Console.WriteLine("For {0}", str);
long arrayLength = (long)((4.0d / 3.0d) *
bytes.Length);
// If array length is not divisible
// by 4, go up to the next multiple
// of 4.
if (arrayLength % 4 != 0)
arrayLength += 4 - arrayLength % 4;
// creating object of char array
char[] base64CharArray = new char[arrayLength];
// converting byte to base 64 string
int val = Convert.ToBase64CharArray(bytes, 0,
bytes.Length, base64CharArray, 0);
Console.WriteLine("Total no of bytes: {0}", val);
// display the base64CharArray
Console.Write("base64CharArray: ");
for (int j = 0; j < base64CharArray.Length; j++)
Console.Write("{0}", base64CharArray[j]);
Console.WriteLine("\n");
}
}
输出：
For byte1
Total no of bytes: 16
base64CharArray: AgQGCAoMDhASFA==
inArray and outArray are null.
Exception Thrown: System.ArgumentNullException
示例3：对于ArgumentOutOfRangeException
// C# program to demonstrate the
// Convert.FromBase64String(String)
// Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// defining and initializing
// byte1 and byte2
byte[] byte1 = {2, 4, 6, 8, 10, 12,
14, 16, 18, 20};
byte[] byte2 = {10, 20, 30, 40, 50};
// calling get() Method
get(byte1, "byte1");
// converting base 64 string
// to byte array
Console.WriteLine("length of inArray is negative");
char[] base64CharArray = new char[10];
int val = Convert.ToBase64CharArray(byte2, 0,
-10, base64CharArray, 0);
Console.WriteLine("Converted byte value: {0}", val);
}
catch (ArgumentNullException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
catch (ArgumentOutOfRangeException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(),
e.Message);
}
}
// Defining get() method
public static void get(byte[] bytes, string str)
{
Console.WriteLine("For {0}", str);
long arrayLength = (long)((4.0d / 3.0d) * bytes.Length);
// If array length is not divisible
// by 4, go up to the next multiple
// of 4.
if (arrayLength % 4 != 0)
arrayLength += 4 - arrayLength % 4;
// creating object of char array
char[] base64CharArray = new char[arrayLength];
// converting byte to base 64 string
int val = Convert.ToBase64CharArray(bytes, 0,
bytes.Length, base64CharArray, 0);
Console.WriteLine("Total no of bytes: {0}", val);
// display the base64CharArray
Console.Write("base64CharArray: ");
for (int j = 0; j < base64CharArray.Length; j++)
Console.Write("{0}", base64CharArray[j]);
Console.WriteLine("\n");
}
}
输出：
For byte1
Total no of bytes: 16
base64CharArray: AgQGCAoMDhASFA==
length of inArray is negative
Exception Thrown: System.ArgumentOutOfRangeException
参考：
- https://docs.microsoft.com/zh-cn/dotnet/api/system.convert.tobase64chararray?view=netframework-4.7.2#System_Convert_ToBase64CharArray_System_Byte___System_Int32_System_Int32_System_Char___System_Int32_