如果你关心性能，不要使用int型。TryParse或Regex -编写自己的(简单的)函数(下面是DigitsOnly或DigitsOnly2，但不是DigitsOnly3 - LINQ似乎会引起很大的开销)。

另外，要注意int。如果字符串太长，不能“适合”int, TryParse将失败。

这个简单的基准测试…

class Program {

    static bool DigitsOnly(string s) {
        int len = s.Length;
        for (int i = 0; i < len; ++i) {
            char c = s[i];
            if (c < '0' || c > '9')
                return false;
        }
        return true;
    }

    static bool DigitsOnly2(string s) {
        foreach (char c in s) {
            if (c < '0' || c > '9')
                return false;
        }
        return true;
    }

    static bool DigitsOnly3(string s) {
        return s.All(c => c >= '0' && c <= '9');
    }

    static void Main(string[] args) {

        const string s1 = "916734184";
        const string s2 = "916734a84";

        const int iterations = 1000000;
        var sw = new Stopwatch();

        sw.Restart();
        for (int i = 0 ; i < iterations; ++i) {
            bool success = DigitsOnly(s1);
            bool failure = DigitsOnly(s2);
        }
        sw.Stop();
        Console.WriteLine(string.Format("DigitsOnly: {0}", sw.Elapsed));

        sw.Restart();
        for (int i = 0; i < iterations; ++i) {
            bool success = DigitsOnly2(s1);
            bool failure = DigitsOnly2(s2);
        }
        sw.Stop();
        Console.WriteLine(string.Format("DigitsOnly2: {0}", sw.Elapsed));

        sw.Restart();
        for (int i = 0; i < iterations; ++i) {
            bool success = DigitsOnly3(s1);
            bool failure = DigitsOnly3(s2);
        }
        sw.Stop();
        Console.WriteLine(string.Format("DigitsOnly3: {0}", sw.Elapsed));

        sw.Restart();
        for (int i = 0; i < iterations; ++i) {
            int dummy;
            bool success = int.TryParse(s1, out dummy);
            bool failure = int.TryParse(s2, out dummy);
        }
        sw.Stop();
        Console.WriteLine(string.Format("int.TryParse: {0}", sw.Elapsed));

        sw.Restart();
        var regex = new Regex("^[0-9]+$", RegexOptions.Compiled);
        for (int i = 0; i < iterations; ++i) {
            bool success = regex.IsMatch(s1);
            bool failure = regex.IsMatch(s2);
        }
        sw.Stop();
        Console.WriteLine(string.Format("Regex.IsMatch: {0}", sw.Elapsed));

    }

}

.．.产生以下结果…

DigitsOnly: 00:00:00.0346094
DigitsOnly2: 00:00:00.0365220
DigitsOnly3: 00:00:00.2669425
int.TryParse: 00:00:00.3405548
Regex.IsMatch: 00:00:00.7017648

那么char.IsDigit(myChar)呢?

public bool CheckforDigits(string x)
{    
    int tr;  
    return x.All(r=> int.TryParse(r.ToString(), out tr));
}

非常聪明和简单的方法来检测你的字符串是否只包含数字是这样的:

string s = "12fg";

if(s.All(char.IsDigit))
{
   return true; // contains only digits
}
else
{
   return false; // contains not only digits
}

如果是单个字符串:

if (str.All(Char.IsDigit))
{
  // string contains only digits
}

如果是字符串列表:

if (lstStr.All(s => s.All(Char.IsDigit)))
{
  // List of strings contains only digits
}

您可以尝试使用正则表达式，通过使用c#中的. ismatch(字符串输入，字符串模式)方法测试输入字符串是否只有数字(0-9)。

using System;
using System.Text.RegularExpression;

public namespace MyNS
{
    public class MyClass
    {
        public void static Main(string[] args)
        {
             string input = Console.ReadLine();
             bool containsNumber = ContainsOnlyDigits(input);
        }

        private bool ContainOnlyDigits (string input)
        {
            bool containsNumbers = true;
            if (!Regex.IsMatch(input, @"/d"))
            {
                containsNumbers = false;
            }
            return containsNumbers;
        }
    }
}

问候