本文实例讲述了C#按字节数截取字符串并在后面加上省略号...的方法，这是一个自定义的C#函数，函数的使用说明如下：
原始字符串 提取前endIdex个字节
函数代码如下：
public static string GetSubString(string origStr, int endIndex)
{
if (origStr == null || origStr.Length == 0 || endIndex < 0)
return "";
int bytesCount = System.Text.Encoding.GetEncoding("gb2312").GetByteCount(origStr);
if (bytesCount > endIndex)
{
int readyLength = 0;
int byteLength;
for (int i = 0; i < origStr.Length; i++)
{
byteLength = System.Text.Encoding.GetEncoding("gb2312").GetByteCount(new char[] { origStr[i] });
readyLength += byteLength;
if (readyLength == endIndex)
{
origStr = origStr.Substring(0, i + 1) + "...";
break;
}
else if (readyLength > endIndex)
{
origStr = origStr.Substring(0, i) + "...";
break;
}
}
}
return origStr;
}
以下所示示例也是根据字节数截取字符串的，只是这个函数后面不加省略号……
/// 按字节数截取字符串(不带省略号)
///
/// 原始字符串
/// 提取前endIdex个字节
///
public static string GetSub1String(string origStr, int endIndex)
{
if (origStr == null || origStr.Length == 0 || endIndex < 0)
return "";
int bytesCount = System.Text.Encoding.GetEncoding("gb2312").GetByteCount(origStr);
if (bytesCount > endIndex)
{
int readyLength = 0;
int byteLength;
for (int i = 0; i < origStr.Length; i++)
{
byteLength = System.Text.Encoding.GetEncoding("gb2312").GetByteCount(new char[] { origStr[i] });
readyLength += byteLength;
if (readyLength == endIndex)
{
origStr = origStr.Substring(0, i + 1);
break;
}
else if (readyLength > endIndex)
{
origStr = origStr.Substring(0, i);
break;
}
}
}
return origStr;
}