“定位字符”所代表的是一个虚的字符,它代表一个位置,你也可以直观地认为“定位字符”所代表的是某个字符与字符间的那个微小间隙。
^ 表示其后的字符必须位于字符串的开始处
$ 表示其前面的字符必须位于字符串的结束处
\b 匹配一个单词的边界
\B 匹配一个非单词的边界
另外,还包括:\A 前面的字符必须位于字符处的开始处,\z 前面的字符必须位于字符串的结束处,\Z 前面的字符必须位于字符串的结束处,或者位于换行符前
下面提供一些简单的示例:
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Code
string i = "Live for nothing,die for something";
Regex r1 = new Regex("^Live for nothing,die for something$");
//r1.IsMatch(i) true
Regex r2 = new Regex("^Live for nothing,die for some$");
//r2.IsMatch(i) false
Regex r3 = new Regex("^Live for nothing,die for some");
//r3.IsMatch(i) true
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
string i = @"Live for nothing,
die for something";//多行
Regex r1 = new Regex("^Live for nothing,die for something$");
Console.WriteLine("r1 match count:" + r1.Matches(i).Count);//0
Regex r2 = new Regex("^Live for nothing,die for something$", RegexOptions.Multiline);
Console.WriteLine("r2 match count:" + r2.Matches(i).Count);//0
Regex r3 = new Regex("^Live for nothing,\r\ndie for something$");
Console.WriteLine("r3 match count:" + r3.Matches(i).Count);//1
Regex r4 = new Regex("^Live for nothing,$");
Console.WriteLine("r4 match count:" + r4.Matches(i).Count);//0
Regex r5 = new Regex("^Live for nothing,$", RegexOptions.Multiline);
Console.WriteLine("r5 match count:" + r5.Matches(i).Count);//0
Regex r6 = new Regex("^Live for nothing,\r\n$");
Console.WriteLine("r6 match count:" + r6.Matches(i).Count);//0
Regex r7 = new Regex("^Live for nothing,\r\n$", RegexOptions.Multiline);
Console.WriteLine("r7 match count:" + r7.Matches(i).Count);//0
Regex r8 = new Regex("^Live for nothing,\r$");
Console.WriteLine("r8 match count:" + r8.Matches(i).Count);//0
Regex r9 = new Regex("^Live for nothing,\r$", RegexOptions.Multiline);
Console.WriteLine("r9 match count:" + r9.Matches(i).Count);//1
Regex r10 = new Regex("^die for something$");
Console.WriteLine("r10 match count:" + r10.Matches(i).Count);//0
Regex r11 = new Regex("^die for something$", RegexOptions.Multiline);
Console.WriteLine("r11 match count:" + r11.Matches(i).Count);//1
Regex r12 = new Regex("^");
Console.WriteLine("r12 match count:" + r12.Matches(i).Count);//1
Regex r13 = new Regex("$");
Console.WriteLine("r13 match count:" + r13.Matches(i).Count);//1
Regex r14 = new Regex("^", RegexOptions.Multiline);
Console.WriteLine("r14 match count:" + r14.Matches(i).Count);//2
Regex r15 = new Regex("$", RegexOptions.Multiline);
Console.WriteLine("r15 match count:" + r15.Matches(i).Count);//2
Regex r16 = new Regex("^Live for nothing,\r$\n^die for something$", RegexOptions.Multiline);
Console.WriteLine("r16 match count:" + r16.Matches(i).Count);//1
//对于一个多行字符串,在设置了Multiline选项之后,^和$将出现多次匹配。
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
string i = "Live for nothing,die for something";
string m = "Live for nothing,die for some thing";
Regex r1 = new Regex(@"\bthing\b");
Console.WriteLine("r1 match count:" + r1.Matches(i).Count);//0
Regex r2 = new Regex(@"thing\b");
Console.WriteLine("r2 match count:" + r2.Matches(i).Count);//2
Regex r3 = new Regex(@"\bthing\b");
Console.WriteLine("r3 match count:" + r3.Matches(m).Count);//1
Regex r4 = new Regex(@"\bfor something\b");
Console.WriteLine("r4 match count:" + r4.Matches(i).Count);//1
//\b通常用于约束一个完整的单词
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