VB有一些本地函数用于将字符转换为ASCII值,反之亦然 - Asc()和Chr()。
现在我需要在C#中获得相应的功能。最好的方法是什么?
VB有一些本地函数用于将字符转换为ASCII值,反之亦然 - Asc()和Chr()。
现在我需要在C#中获得相应的功能。最好的方法是什么?
您可以随时添加对 Microsoft.VisualBasic 的引用,然后使用完全相同的方法:Strings.Chr 和 Strings.Asc。
这是获得完全相同功能的最简单方法。
Asc
和Chr
最常见的用途是使用0-126范围内的值,程序员期望将其映射到相应的Unicode代码点;即使有一个系统,例如Chr(34)会产生″
而不是"
,我认为编写Chr(34)
的程序员可能打算使用"
。 - supercat对于Asc()
函数,你可以将char
强制转换为int
类型,如下所示:
int i = (int)your_char;
对于 Chr()
,你可以像这样从 int
转换为 char
:
char c = (char)your_int;
这是一个演示整个过程的小程序:
using System;
class Program
{
static void Main()
{
char c = 'A';
int i = 65;
// both print "True"
Console.WriteLine(i == (int)c);
Console.WriteLine(c == (char)i);
}
}
我使用了resharper来获得这些信息,确切的代码在您的计算机上以VB运行
/// <summary>
/// Returns the character associated with the specified character code.
/// </summary>
///
/// <returns>
/// Returns the character associated with the specified character code.
/// </returns>
/// <param name="CharCode">Required. An Integer expression representing the <paramref name="code point"/>, or character code, for the character.</param><exception cref="T:System.ArgumentException"><paramref name="CharCode"/> < 0 or > 255 for Chr.</exception><filterpriority>1</filterpriority>
public static char Chr(int CharCode)
{
if (CharCode < (int) short.MinValue || CharCode > (int) ushort.MaxValue)
throw new ArgumentException(Utils.GetResourceString("Argument_RangeTwoBytes1", new string[1]
{
"CharCode"
}));
if (CharCode >= 0 && CharCode <= (int) sbyte.MaxValue)
return Convert.ToChar(CharCode);
try
{
Encoding encoding = Encoding.GetEncoding(Utils.GetLocaleCodePage());
if (encoding.IsSingleByte && (CharCode < 0 || CharCode > (int) byte.MaxValue))
throw ExceptionUtils.VbMakeException(5);
char[] chars = new char[2];
byte[] bytes = new byte[2];
Decoder decoder = encoding.GetDecoder();
if (CharCode >= 0 && CharCode <= (int) byte.MaxValue)
{
bytes[0] = checked ((byte) (CharCode & (int) byte.MaxValue));
decoder.GetChars(bytes, 0, 1, chars, 0);
}
else
{
bytes[0] = checked ((byte) ((CharCode & 65280) >> 8));
bytes[1] = checked ((byte) (CharCode & (int) byte.MaxValue));
decoder.GetChars(bytes, 0, 2, chars, 0);
}
return chars[0];
}
catch (Exception ex)
{
throw ex;
}
}
/// <summary>
/// Returns an Integer value representing the character code corresponding to a character.
/// </summary>
///
/// <returns>
/// Returns an Integer value representing the character code corresponding to a character.
/// </returns>
/// <param name="String">Required. Any valid Char or String expression. If <paramref name="String"/> is a String expression, only the first character of the string is used for input. If <paramref name="String"/> is Nothing or contains no characters, an <see cref="T:System.ArgumentException"/> error occurs.</param><filterpriority>1</filterpriority>
public static int Asc(char String)
{
int num1 = Convert.ToInt32(String);
if (num1 < 128)
return num1;
try
{
Encoding fileIoEncoding = Utils.GetFileIOEncoding();
char[] chars = new char[1]
{
String
};
if (fileIoEncoding.IsSingleByte)
{
byte[] bytes = new byte[1];
fileIoEncoding.GetBytes(chars, 0, 1, bytes, 0);
return (int) bytes[0];
}
byte[] bytes1 = new byte[2];
if (fileIoEncoding.GetBytes(chars, 0, 1, bytes1, 0) == 1)
return (int) bytes1[0];
if (BitConverter.IsLittleEndian)
{
byte num2 = bytes1[0];
bytes1[0] = bytes1[1];
bytes1[1] = num2;
}
return (int) BitConverter.ToInt16(bytes1, 0);
}
catch (Exception ex)
{
throw ex;
}
}
/// <summary>
/// Returns an Integer value representing the character code corresponding to a character.
/// </summary>
///
/// <returns>
/// Returns an Integer value representing the character code corresponding to a character.
/// </returns>
/// <param name="String">Required. Any valid Char or String expression. If <paramref name="String"/> is a String expression, only the first character of the string is used for input. If <paramref name="String"/> is Nothing or contains no characters, an <see cref="T:System.ArgumentException"/> error occurs.</param><filterpriority>1</filterpriority>
public static int Asc(string String)
{
if (String == null || String.Length == 0)
throw new ArgumentException(Utils.GetResourceString("Argument_LengthGTZero1", new string[1]
{
"String"
}));
return Strings.Asc(String[0]);
}
资源只是存储错误消息的方式,因此您需要找到忽略它们的方法。而另外两种方法,您无法访问,具体如下:
internal static Encoding GetFileIOEncoding()
{
return Encoding.Default;
}
internal static int GetLocaleCodePage()
{
return Thread.CurrentThread.CurrentCulture.TextInfo.ANSICodePage;
}
Convert.ToChar(CharCode);
,我可以在自己的代码中处理检查,而不必导入VB! - HackSlashStrings.Asc不能对超过127的非ASCII字符进行普通的C#转换。我在https://social.msdn.microsoft.com/Forums/vstudio/en-US/13fec271-9a97-4b71-ab28-4911ff3ecca0/equivalent-in-c-of-asc-chr-functions-of-vb?forum=csharpgeneral上找到的答案类似于这样:
static int Asc(char c)
{
int converted = c;
if (converted >= 0x80)
{
byte[] buffer = new byte[2];
// if the resulting conversion is 1 byte in length, just use the value
if (System.Text.Encoding.Default.GetBytes(new char[] { c }, 0, 1, buffer, 0) == 1)
{
converted = buffer[0];
}
else
{
// byte swap bytes 1 and 2;
converted = buffer[0] << 16 | buffer[1];
}
}
return converted;
}
或者,如果你想要真正的效果,请添加对Microsoft.VisualBasic程序集的引用。
对于 Chr(),您可以使用以下方法:
char chr = (char)you_char_value;
int intValue = 65; \\ Letter A
string strVal = Char.ConvertFromUtf32(intValue);
Dim intValue as integer = 65
Dim strValue As String = Char.ConvertFromUtf32(intValue)
不需要 Microsoft.VisualBasic 引用
以下程序对于我在 .net standard 2.0 + .net 5 的 COM Interop 服务器环境以及使用代码页为1252的Classic ASP/VB6客户端是有效的。
我尚未测试其在其他代码页上的效果:
public static int Asc(char String)
{
int int32 = Convert.ToInt32(String);
if (int32 < 128)
return int32;
Encoding encoding = CodePagesEncodingProvider.Instance.GetEncoding(Thread.CurrentThread.CurrentCulture.TextInfo.ANSICodePage);
char[] chars = new char[1] { String };
if (encoding.IsSingleByte)
{
byte[] bytes = new byte[1];
encoding.GetBytes(chars, 0, 1, bytes, 0);
return (int)bytes[0];
}
byte[] bytes1 = new byte[2];
if (encoding.GetBytes(chars, 0, 1, bytes1, 0) == 1)
return (int)bytes1[0];
if (BitConverter.IsLittleEndian)
{
byte num = bytes1[0];
bytes1[0] = bytes1[1];
bytes1[1] = num;
}
return (int)BitConverter.ToInt16(bytes1, 0);
}
private int Asc(char String)
{
int int32 = Convert.ToInt32(String);
if (int32 < 128)
return int32;
try
{
Encoding fileIoEncoding = Encoding.Default;
char[] chars = new char[1] { String };
if (fileIoEncoding.IsSingleByte)
{
byte[] bytes = new byte[1];
fileIoEncoding.GetBytes(chars, 0, 1, bytes, 0);
return (int)bytes[0];
}
byte[] bytes1 = new byte[2];
if (fileIoEncoding.GetBytes(chars, 0, 1, bytes1, 0) == 1)
return (int)bytes1[0];
if (BitConverter.IsLittleEndian)
{
byte num = bytes1[0];
bytes1[0] = bytes1[1];
bytes1[1] = num;
}
return (int)BitConverter.ToInt16(bytes1, 0);
}
catch (Exception ex)
{
throw ex;
}
}
`
我已经从Microsoft.VisualBasic.dll中提取了Asc()函数:
public static int Asc(char String)
{
int num;
byte[] numArray;
int num1 = Convert.ToInt32(String);
if (num1 >= 128)
{
try
{
Encoding fileIOEncoding = Encoding.Default;
char[] str = new char[] { String };
if (!fileIOEncoding.IsSingleByte)
{
numArray = new byte[2];
if (fileIOEncoding.GetBytes(str, 0, 1, numArray, 0) != 1)
{
if (BitConverter.IsLittleEndian)
{
byte num2 = numArray[0];
numArray[0] = numArray[1];
numArray[1] = num2;
}
num = BitConverter.ToInt16(numArray, 0);
}
else
{
num = numArray[0];
}
}
else
{
numArray = new byte[1];
fileIOEncoding.GetBytes(str, 0, 1, numArray, 0);
num = numArray[0];
}
}
catch (Exception exception)
{
throw exception;
}
}
else
{
num = num1;
}
return num;
}