此方法用于返回从字节数组中指定位置的八个字节转换而来的64位无符号整数。
句法：
public static ulong ToUInt64 (byte[] value, int startIndex);参数：
value: It is an array of bytes.
startIndex: It is the starting position within value.
返回值：该方法返回一个以startIndex开始的八个字节组成的64位无符号整数。
例外情况：
- ArgumentException：如果startIndex大于或等于值的长度减去7，并且小于或等于值的长度减去1。
- ArgumentNullException：如果该值为null。
- ArgumentOutOfRangeException：如果startIndex小于零或大于值的长度减去1。
下面的程序说明了BitConverter.ToUInt64方法的用法：
范例1：
// C# program to demonstrate
// BitConverter.ToUInt64(Byte[], Int32);
// Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// Define an array of byte values.
byte[] bytes = {32, 0, 0, 42, 0, 65,
0, 125, 0, 197, 0,
168, 3, 41, 4, 125,32};
// Display the values of the myArr.
Console.Write("Initial Array: ");
// calling the PrintIndexAndValues()
// method to print
PrintIndexAndValues(bytes);
// print char value
Console.WriteLine("index byte Array"+
" ulong value");
for (int index = 0; index < bytes.Length - 7;
index = index + 8) {
ulong values = BitConverter.ToUInt64(bytes, index);
Console.WriteLine(" {0} {1} {2}", index,
BitConverter.ToString(bytes,
index, 8), values);
}
}
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);
}
catch (ArgumentException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
}
// Defining the method
// PrintIndexAndValues
public static void PrintIndexAndValues(byte[] myArr)
{
for (int i = 0; i < myArr.Length; i++) {
Console.Write("{0} ", myArr[i]);
}
Console.WriteLine();
Console.WriteLine();
}
}
输出：
Initial Array: 32 0 0 42 0 65 0 125 0 197 0 168 3 41 4 125 32
index byte Array ulong value
0 20-00-00-2A-00-41-00-7D 9007270723701440544
8 00-C5-00-A8-03-29-04-7D 9008370250328098048
示例2：对于ArgumentException
// C# program to demonstrate
// BitConverter.ToUInt64(Byte[], Int32);
// Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// Define an array of byte values.
byte[] bytes = {32, 0, 0, 42, 0, 65,
0, 125, 0, 197, 0,
168, 3, 41, 4, 125,32};
// Display the values of the myArr.
Console.Write("Initial Array: ");
// calling the PrintIndexAndValues()
// method to print
PrintIndexAndValues(bytes);
// print char value
Console.WriteLine("index element"+
" ulong value");
for (int index = 0; index < bytes.Length + 1;
index = index + 8) {
if (index == bytes.Length) {
Console.WriteLine();
Console.WriteLine("startindex is {0} which is greater than "
+ "the length of Array minus 1.", index);
ulong values = BitConverter.ToUInt64(bytes, index);
Console.WriteLine(" {0} {1} {2}", index,
BitConverter.ToString(bytes, index, 8), values);
}
else {
ulong values = BitConverter.ToUInt64(bytes, index);
Console.WriteLine(" {0} {1} {2}", index,
BitConverter.ToString(bytes, index, 8), values);
}
}
}
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);
}
catch (ArgumentException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
}
// Defining the method
// PrintIndexAndValues
public static void PrintIndexAndValues(byte[] myArr)
{
for (int i = 0; i < myArr.Length; i++) {
Console.Write("{0} ", myArr[i]);
}
Console.WriteLine();
Console.WriteLine();
Console.WriteLine("intial Array in string: {0} ",
BitConverter.ToString(myArr));
Console.WriteLine();
}
}
输出：
Initial Array: 32 0 0 42 0 65 0 125 0 197 0 168 3 41 4 125 32
intial Array in string: 20-00-00-2A-00-41-00-7D-00-C5-00-A8-03-29-04-7D-20
index element ulong value
0 20-00-00-2A-00-41-00-7D 9007270723701440544
8 00-C5-00-A8-03-29-04-7D 9008370250328098048
Exception Thrown: System.ArgumentException
示例3：对于ArgumentNullException
// C# program to demonstrate
// BitConverter.ToUInt64(Byte[], Int32);
// Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// Define an array of byte values.
byte[] bytes = null;
// get the long value
ulong values = BitConverter.ToUInt64(bytes, 0);
Console.Write("{0}", values);
}
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);
}
catch (ArgumentException e) {
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
}
}
输出：
Exception Thrown: System.ArgumentNullException
参考：
- https://docs.microsoft.com/zh-cn/dotnet/api/system.bitconverter.touint64?view=netframework-4.7.2