(1)“@”符号
符下两ows表研究室的火热,当晨在“@”虽然并非C#正则表达式的“成员”,但是它经常与C#正则表达式出双入对。“@”表示,跟在它后面的字符串是个“逐字字符串”,不是很好理解,举个例子,以下两个声明是等效的:
string x="D:My HuangMy Doc";
string y = @"D:My HuangMy Doc";
事实上,如果按如下声明,C#将会报错,因为“”在C#中用于实现转义,如“n”换行:
string x = "D:My HuangMy Doc";
(2)基本的语法字符。
d 0-9的数字
D d的补集(以所以字符为全集,下同),即所有非数字的字符
w 单词字符,指大小写字母、0-9的数字、下划线
W w的补集
s 空白字符,包括换行符n、回车符r、制表符t、垂直制表符v、换页符f
S s的补集
. 除换行符n外的任意字符
[…] 匹配[]内所列出的所有字符
[^…] 匹配非[]内所列出的字符
下面提供一些简单的示例:
复制代码 代码如下:
string i = "n";
string m = "3";
Regex r = new Regex(@"D");
//同Regex r = new Regex("D");
//r.IsMatch(i)结果:true
//r.IsMatch(m)结果:false
string i = "%";
string m = "3";
Regex r = new Regex("[a-z0-9]");
//匹配小写字母或数字字符
//r.IsMatch(i)结果:false
//r.IsMatch(m)结果:true
3)定位字符
“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:
复制代码 代码如下:
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
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,rndie 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,$", RegexOptions.Multiline);
Console.WriteLine("r5 match count:" + r5.Matches(i).Count);//0
Regex r6 = new Regex("^Live for nothing,rn$");
Console.WriteLine("r6 match count:" + r6.Matches(i).Count);//0
Regex r7 = new Regex("^Live for nothing,rn$", RegexOptions.Multiline);
Console.WriteLine("r7 match count:" + r7.Matches(i).Count);//0
Regex r8 = new Regex("^Live for nothing,r$");
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。
string i = "Live for nothing,die for something";
string m = "Live for nothing,die for some thing";
Regex r1 = new Regex(@"bthingb");
Console.WriteLine("r1 match count:" + r1.Matches(i).Count);//0
Regex r2 = new Regex(@"thingb");
Console.WriteLine("r2 match count:" + r2.Matches(i).Count);//2
Regex r3 = new Regex(@"bthingb");
Console.WriteLine("r3 match count:" + r3.Matches(m).Count);//1
Regex r4 = new Regex(@"bfor somethingb");
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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