This is the input string 23x * y34x2. I want to insert " * " (star surrounded by whitespaces) after every number followed by letter, and after every letter followed by number. So my input string would look like this: 23 * x * y * 34 * x * 2.
这是输入字符串23x * y34x2。我想在每个数字后面跟字母，在每个字母后面跟数字后面加上“*”(由白色空格包围的星号)。输入字符串是这样的:23 * x * y * 34 * x * 2。
This is the regex that does the job: @"\d(?=[a-z])|[a-z](?=\d)". This is the function that I wrote that inserts the " * ".
这个正则表达式的工作:@“\ d(? =[a - z])|[a - z](? = \ d)”。这是我编写的插入“*”的函数。
Regex reg = new Regex(@"\d(?=[a-z])|[a-z](?=\d)");
MatchCollection matchC;
matchC = reg.Matches(input);
int ii = 1;
foreach (Match element in matchC)//foreach match I will find the index of that match
{
input = input.Insert(element.Index + ii, " * ");//since I' am inserting " * " ( 3 characters )
ii += 3; //I must increment index by 3
}
return input; //return modified input
My question how to do same job using .net MatchEvaluator? I'am new to regex and don't understand good replacing with MatchEvaluator. This is the code that I tried to wrote:
我的问题是如何使用。net MatchEvaluator来做同样的工作?我是regex的新手，不明白用MatchEvaluator代替是什么意思。这是我试着写的代码:
Regex reg = new Regex(@"\d(?=[a-z])|[a-z](?=\d)");
MatchEvaluator matchEval = new MatchEvaluator(ReplaceStar);
input = reg.Replace(input, matchEval);
return input;
}
public string ReplaceStar( Match match )
{
//return What??
}
1 个解决方案
#1
53
A MatchEvaluator is a delegate that takes a Match object and returns a string that should be replaced instead of the match. You can also refer to groups from the match. You can rewrite your code as follows:
MatchEvaluator是一个委托，它接受Match对象并返回一个应该替换而不是匹配的字符串。您还可以引用来自匹配的组。您可以重写代码如下:
string input = "23x * y34x2";
Regex reg = new Regex(@"\d(?=[a-z])|[a-z](?=\d)");
string result = reg.Replace(input, delegate(Match m) {
return m.Value + " * ";
});
To give an example of how this works, the first time the delegate is called, Match parameter will be a match on the string "3". The delegate in this case is defined to return the match itself as a string concatenated with " * ". So the first "3" is replaced with "3 * ".
为了举例说明该如何工作，第一次调用委托时，Match参数将是字符串“3”上的匹配。在本例中，委托被定义为将匹配本身作为与“*”连接的字符串返回。所以第一个3被3 *取代。
The process continues in this way, with delegate being called once for each match in the original string.
这个过程以这种方式继续，在原始字符串中，每个匹配都被调用一次。
#1
53
A MatchEvaluator is a delegate that takes a Match object and returns a string that should be replaced instead of the match. You can also refer to groups from the match. You can rewrite your code as follows:
MatchEvaluator是一个委托，它接受Match对象并返回一个应该替换而不是匹配的字符串。您还可以引用来自匹配的组。您可以重写代码如下:
string input = "23x * y34x2";
Regex reg = new Regex(@"\d(?=[a-z])|[a-z](?=\d)");
string result = reg.Replace(input, delegate(Match m) {
return m.Value + " * ";
});
To give an example of how this works, the first time the delegate is called, Match parameter will be a match on the string "3". The delegate in this case is defined to return the match itself as a string concatenated with " * ". So the first "3" is replaced with "3 * ".
为了举例说明该如何工作，第一次调用委托时，Match参数将是字符串“3”上的匹配。在本例中，委托被定义为将匹配本身作为与“*”连接的字符串返回。所以第一个3被3 *取代。
The process continues in this way, with delegate being called once for each match in the original string.
这个过程以这种方式继续，在原始字符串中，每个匹配都被调用一次。