检查字符串是否包含忽略大小写的字符

Question

I have a textbox on GUI which takes an "Mobile Number" as input. I want to validate it to find out if it has some characters, which would mean the number is invalid

So, a number 9876543210 is valid while a number 98765df013 is invalid

I made a array of all characters (which are not allowed by me)

string[] alphabeticChars       = new string[] {    
                                                                    "a", "b", "c", "d", "e", "f", "g",
                                                                    "h", "i", "j", "k", "l", "m", "n",
                                                                    "o", "p", "q", "r", "s", "t", "u",
                                                                    "v", "w", "x", "y", "z"
                                                               };

and then I wrote a validation function

public bool HasCharacters(string text)
{
    foreach(string character in this.alphabeticChars)
         if(text.Contains(character.ToLower()) || text.Contains(character.ToUpper())) 
                return true;

    return false;
}

As you can see, I need to call Contains twice, one for "Lower Case" and another time for "Upper Case". I checked and couldn't find ContainsIgnoreCase or something.

What is the best way to to such a thing ? (Don't mention regular expressions, as I don't want to use them)

Answer 1

In a very simple way :-)

foreach(string character in this.alphabeticChars)
     if(text.ToLower().Contains(character)) 
            return true;

Or maybe you can do a regular expression which is more efficient

Answer 2

My answer it is not exactly what you are asking, it more suggestion, better way to validate phone numbers is using of libphonenumber (c#) library https://libphonenumber.codeplex.com that is port of Google libphonenumber. I have found it as the best way to do it for me. You can validate numbers based on country code and to format them in output.

Update. Here is more up to date version of the library https://www.nuget.org/packages/libphonenumber-csharp/

Answer 3

尝试这个：

bool isValid = !text.Any(c => Char.IsLetter(c));

Answer 4

My take, using Linq:

public static class StringExtensions
{
    public static bool ContainsOnlyDigits(this string s)
    {
        return s.All(c => c >= '0' && c <= '9');
    }
}

And in use:

var result = "12345678".ContainsOnlyDigits();

Answer 5

由于您似乎想测试数字（因为您的预期输入是“手机号码”，因此它可能是单行代码：

bool isValid = text.All(Char.IsDigit);

Answer 6

Instead of checking the presence of a character, switch that logic around and just verify that everything is a number:

public bool IsNumeric(string text)
{
    return text.All(char.IsDigit);
}