Need regex to match strings which begin with numbers

Question

I need regular expression to match strings, which begin from number (number can be integer or float). For example:

100px
100 px
1.0ft
1.0 ft
0.001ft2
0.001 ft2

I'm new in this stuff, can anyone help me, please? I've already tried something like:

Regex numberBeginRegex = new Regex(@"([\d]+|[\d]+[.][\d]+).");

Are these examples full strings and you want to validate their correct format? Or do you want to find substrings like these in larger input strings? — Martin Ender
– Martin Ender, Commented Dec 4, 2012 at 16:28

Rohit Jain · Accepted Answer · 2012-12-04 16:38:46Z

3

You can use this regex: -

"(\d+(\.\d+)?).*"

(\d+(\.\d+)?) - matches integer number or floating point numbers. The fractional part is made optional by using ? quantifier, which means - match 0 or 1

Actually your regex would have worked too, but you forgot to put * quantifier at the end of .: -

"([\d]+|[\d]+[.][\d]+).*"  // Note the `*` at the end

edited Dec 4, 2012 at 16:38

answered Dec 4, 2012 at 16:29

Rohit Jain

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3 Comments

Rohit Jain Over a year ago

@Some1.Kill.The.DJ.. Why? It is required to match the following string.

Anirudha Over a year ago

that would also match 435.5px hello world if you donot use groups..OP wants output like 100px 100 px 1.0ft

Rohit Jain Over a year ago

@Some1.Kill.The.DJ.. But this is nowhere specified in the question that he wants to match words. OP said he wants to match sentence. But this can be altered easily to match words.

Anirudha · Accepted Answer · 2012-12-04 16:44:21Z

1

You can use this regex

 var reg=@"^(\d+(\.\d+)?).*";
 List<string> nums=Regex.Matches(inp,reg,RegexOptions.Multiline)
                        .Cast<Match>()
                        .Select(x=>x.Value)
                        .ToList();

edited Dec 4, 2012 at 16:44

answered Dec 4, 2012 at 16:30

Anirudha

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Comments

CR41G14 · Accepted Answer · 2012-12-04 16:29:41Z

0

If you want to check if they start with a number you can use substring() to get the first char

answered Dec 4, 2012 at 16:29

CR41G14

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1 Comment

hometoast Over a year ago

string mysubject="..."; If (char.IsDigit(mysubject.FirstOrDefault()) ...

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