正则表达式选择一个单词的一部分

Question

I have a text like this:

my text has $1 per Lap to someone. 

Could anyone tell me how to pick the per part from it. I know how to pick the $ amount. It's like this:

new Regex(@"\$\d+(?:\.\d+)?").Match(s.Comment1).Groups[0].ToString()

Any help would be highly appreciated.

Answer 1

In case you have multiple substrings you need inside a larger string, you can use capturing groups.

To obtain the per part, use the following regex and grab the Groups[2].Value :

var str = "my text has $1 per Lap to someone. ";
var per_str = new Regex(@"(\$\d+(?:\.\d+)?)\s*(\p{L}+)").Match(str).Groups[2].Value;

Output:

The regex to capture per is \\p{L}+ where \\p{L} captures all Unicode letters (eg ф , ё ), not just Latin script.

To get the number part, use the same regex, but grab Groups[1].Value :

var num_str = new Regex(@"(\$\d+(?:\.\d+)?)\s*(\p{L}+)").Match(str).Groups[1].Value;

Output:

And another tip : compile your regex first if you plan to use it multiple times during your app execution:

var rx = new Regex(@"(\$\d+(?:\.\d+)?)\s*(\p{L}+)", RegexOptions.Compiled);
var per_str = rx.Match(str).Groups[2].Value;
var num_str = rx.Match(str).Groups[1].Value;

In case you need just a number after $ , just put the opening round bracket after it in the regex: @"\\$(\\d+(?:\\.\\d+)?)\\s*(\\p{L}+)" .

And to get all groups in 1 go, you can use

var groups = rx.Matches(str).Cast<Match>().Select(p => new { num = p.Groups[1].Value, per = p.Groups[2].Value }).ToList();

EDIT:

If you just want to match per after the number, you can use @"(\\$\\d+(?:\\.\\d+)?)\\s*(per)" or (case-insensitive) @"(\\$\\d+(?:\\.\\d+)?)\\s*((?i:per\\b))"

Answer 2

As you said that per is a string type the following simple regex can does the job for you :

\$\d+\s([a-zA-Z]+)

But if the per is contain digits you can use \\w that match word characters :

\$\d+\s(\w+)

Demo

Note that in this case per is in the first capture group and you need to extract the first group.

Also you can use a positive look behind if you dont want to use grouping :

(?<=\$\d+\s)[a-zA-Z]+

If the per is a special word you can check with following regex :

(?<=\$\d+\s)per

Something like :

var per_str = new Regex(@'(?<=\$\d+\s)per').Match(str).Groups[0].Value;
if (per_str != ''){
#dostuff
}

Answer 3

(?<=\$\d+(?:\.\d+)?\s+)\S+

这应该为你做。

Answer 4

As @Sayse said, you don't need a Regex here. I made two solutions without.

Check the Demo or read the code :

public static void Main()
{
    var s = "my text has $1 per Lap to someone.";

    Console.WriteLine(Test(s));
    Console.WriteLine(Test2(s));
}

static object Test(string s)
{           
    var tab = s.Remove(s.IndexOf(" Lap"))       // remove everything after " Lap" 
               .Substring(s.IndexOf(" $") + 2)  // remove everything before " $"
               .Split(' ');

    return new { Amount = tab[0], Per = tab[1] };
}

static object Test2(string s)
{
    var tab = s.Split(' ');
    var amount = tab.Single(t => t.StartsWith("$")).Substring(1);
    var per = tab[Array.FindIndex(tab, t => t.StartsWith("$")) + 1];

    return new { Amount = amount, Per = per };
}

output

{ Amount = 1, Per = per }
{ Amount = 1, Per = per }