C#“字符串之间”运行多次

Question

Here is my code to find a string between { } :

var text = "Hello this is a {Testvar}...";
int tagFrom = text.IndexOf("{") + "{".Length;
int tagTo = text.LastIndexOf("}");
String tagResult = text.Substring(tagFrom, tagTo - tagFrom);

tagResult Output: Testvar

This only works for one time use. How can I apply this for several Tags? (eg in a While loop)

For example:

var text = "Hello this is a {Testvar}... and we have more {Tagvar} in this string {Endvar}.";

tagResult[] Output (eg Array): Testvar , Tagvar , Endvar

Answer 1

IndexOf() has another overload that takes the start index of which starts to search the given string. if you omit it, it will always look from the beginning and will always find the first one.

 var text = "Hello this is a {Testvar}...";
    int start = 0, end = -1;
    List<string> results = new List<string>();
    while(true)
    {
        start = text.IndexOf("{", start) + 1;
        if(start != 0)
           end = text.IndexOf("}", start);
        else
           break;
        if(end==-1) break;
        results.Add(text.Substring(start, end - start));
        start = end + 1;  
    }

Answer 2

I would use Regex pattern {(\\\\w+)} to get the value.

Regex reg = new Regex("{(\\w+)}");     
var text = "Hello this is a {Testvar}... and we have more {Tagvar} in this string {Endvar}.";
string[] tagResult = reg.Matches(text)
    .Cast<Match>()
    .Select(match => match.Groups[1].Value).ToArray();
foreach (var item in tagResult)
{
    Console.WriteLine(item);
}

c# online

Result

Testvar
Tagvar
Endvar

Answer 3

I strongly recommend using regular expressions for the task.

using System;
using System.Text.RegularExpressions;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var regex = new Regex(@"(\{(?<var>\w*)\})+", RegexOptions.IgnoreCase);
            var text = "Hello this is a {Testvar}... and we have more {Tagvar} in this string {Endvar}.";
            var matches = regex.Matches(text);

            foreach (Match match in matches)
            {
                var variable = match.Groups["var"];
                Console.WriteLine($"Found {variable.Value} from position {variable.Index} to {variable.Index + variable.Length}");
            }
        }        
    }
}

Output:

Found Testvar from position 17 to 24

Found Tagvar from position 47 to 53

Found Endvar from position 71 to 77

For more information about regular expression visit the MSDN reference page:

https://docs.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-language-quick-reference

and this tool may be great to start testing your own expressions:

http://regexstorm.net/tester

Hope this help!

Answer 4

Many ways to skin this cat, here are a few:

• Split it on { then loop through, splitting each result on } and taking element 0 each time

• Split on { or } then loop through taking only odd numbered elements

• Adjust your existing logic so you use IndexOf twice (instead of lastindexof). When you're looking for a } pass the index of the { as the start index of the search

Answer 5

This is so easy by using Regular Expressions just by using a simple pattern like {([\\d\\w]+)} . See the example below:-

using System.Text.RegularExpressions;
...
MatchCollection matches = Regex.Matches("Hello this is a {Testvar}... and we have more {Tagvar} in this string {Endvar}.", @"{([\d\w]+)}");
foreach(Match match in matches){
    Console.WriteLine("match : {0}, index : {1}", match.Groups[1], match.index);
}

It can find any series of letters or number in these brackets one by one.