In C#, how to check whether a string contains an i

问题:

I just want to know, whether a String variable contains a parsable positive integer value. I do NOT want to parse the value right now.

Currently I am doing:

int parsedId;
if (
    (String.IsNullOrEmpty(myStringVariable) ||
    (!uint.TryParse(myStringVariable, out parsedId))
)
{//..show error message}

This is ugly - How to be more concise?

Note: I know about extension methods, but I wonder if there is something built-in.

回答1:

You could use char.IsDigit:

     bool isIntString = "your string".All(char.IsDigit)

Will return true if the string is a number

    bool containsInt = "your string".Any(char.IsDigit)

Will return true if the string contains a digit

回答2:

Assuming you want to check that all characters in the string are digits, you could use the Enumerable.All Extension Method with the Char.IsDigit Method as follows:

bool allCharactersInStringAreDigits = myStringVariable.All(char.IsDigit);

回答3:

You can check if string contains numbers only:

Regex.IsMatch(myStringVariable, @"^-?\d+$")

But number can be bigger than Int32.MaxValue or less than Int32.MinValue - you should keep that in mind.

Another option - create extension method and move ugly code there:

public static bool IsInteger(this string s)
{
   if (String.IsNullOrEmpty(s))
       return false;

   int i;
   return Int32.TryParse(s, out i);
}

That will make your code more clean:

if (myStringVariable.IsInteger())
    // ...

回答4:

Maybe this can help

string input = "hello123world";
bool isDigitPresent = input.Any(c => char.IsDigit(c));

answer from msdn.

回答5:

The answer seems to be just no.

Although there are many good other answers, they either just hide the uglyness (which I did not ask for) or introduce new problems (edge cases).

回答6:

Sorry, didn't quite get your question. So something like this?

str.ToCharArray().Any(char.IsDigit);

Or does the value have to be an integer completely, without any additional strings?

if(str.ToCharArray().All(char.IsDigit(c));