使用此方法，以指示在指定字符串中指定位置的字符是否具有代理项代码单元或没有。
句法：
public static bool IsSurrogate (string s, int index);参数：
s: It is a String.
index: It is the character position to evaluate in s.
返回值：如果s中位置索引处的字符是高替代或低替代，则此方法返回true ，否则返回false 。
例外情况：
- ArgumentNullException：如果s为null。
- ArgumentOutOfRangeException：如果该指数大于最后一个位置旅店s时小于零或。
下面的程序说明了Char.IsSurrogate(String，Int32)方法的用法：
范例1：
// C# program to demonstrate
// Char.IsSurrogate(String,
// Int32) Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// calling check() Method
check("1234", 3);
check("Tsunami", 3);
check("psyc0lo", 4);
// declaring and initializing string s1
string s1 = new String(new char[] {'a',
'\uD800', '\uDC00', 'z' });
check(s1, 2);
}
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 check() method
public static void check(string s, int i)
{
// checking condition
bool val = Char.IsSurrogate(s, i);
// checking
if (val)
Console.WriteLine("String '{0}' contains "
+ "Surrogate value at index {1} ",s, i);
else
Console.WriteLine("String '{0}' does't contain any"
+ "Surrogate value at index {1}",s, i);
}
}
输出：
String '1234' does't contain anySurrogate value at index 3
String 'Tsunami' does't contain anySurrogate value at index 3
String 'psyc0lo' does't contain anySurrogate value at index 4
String 'að??z' contains Surrogate value at index 2
示例2：对于ArgumentNullException
// C# program to demonstrate
// Char.IsSurrogate(String,
// Int32) Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// calling check() Method
check("1234", 3);
check("Tsunami", 3);
check("psyc0lo", 4);
// declaring and initializing string s1
string s1 = new String(new char[] { 'a',
'\uD800', '\uDC00', 'z' });
check(s1, 2);
Console.WriteLine("");
Console.WriteLine("s is null");
check(null, 4);
}
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 check() method
public static void check(string s, int i)
{
// checking condition
bool val = Char.IsSurrogate(s, i);
// checking
if (val)
Console.WriteLine("String '{0}' contains "
+ "Surrogate value at index {1} ",s, i);
else
Console.WriteLine("String '{0}' does't contain any"
+ "Surrogate value at index {1}", s, i);
}
}
输出：
String '1234' does't contain anySurrogate value at index 3
String 'Tsunami' does't contain anySurrogate value at index 3
String 'psyc0lo' does't contain anySurrogate value at index 4
String 'að??z' contains Surrogate value at index 2
s is null
Exception Thrown: System.ArgumentNullException
示例3：对于ArgumentOutOfRangeException
// C# program to demonstrate
// Char.IsSurrogate(String,
// Int32) Method
using System;
class GFG {
// Main Method
public static void Main()
{
try {
// calling check() Method
check("1234", 3);
check("Tsunami", 3);
check("psyc0lo", 4);
// declaring and initializing string s1
string s1 = new String(new char[] {'a',
'\uD800', '\uDC00', 'z' });
check(s1, 2);
Console.WriteLine("");
Console.WriteLine("index is less than zero");
check("null", -4);
}
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 check() method
public static void check(string s, int i)
{
// checking condition
bool val = Char.IsSurrogate(s, i);
// checking
if (val)
Console.WriteLine("String '{0}' contains "
+ "Surrogate value at index {1} ", s, i);
else
Console.WriteLine("String '{0}' does't contain any"
+ "Surrogate value at index {1}", s, i);
}
}
输出：
String '1234' does't contain anySurrogate value at index 3
String 'Tsunami' does't contain anySurrogate value at index 3
String 'psyc0lo' does't contain anySurrogate value at index 4
String 'að??z' contains Surrogate value at index 2
index is less than zero
Exception Thrown: System.ArgumentOutOfRangeException
参考：
- https://docs.microsoft.com/zh-cn/dotnet/api/system.char.issurrogate?view=netframework-4.7.2#System_Char_IsSurrogate_System_String_System_Int32_