c# integer validation compactframework

问题

Using the .Net Compact Framework 2.0, how can I validate an integer (Int32.TryParse is not supported on the Compact Framework)?

回答1:

What do you mean by "validate"? Do you mean parse without throwing?

static bool TryParse(string s, out int value)        
{
    try
    {
        value = int.Parse(s);
        return true;
    }
    catch
    {
        value = 0;
        return false;
    }
}

回答2:

  static bool TryParseImpl(string s, int start, ref int value)
  {
    if (start == s.Length) return false;
    unchecked {
      int i = start;
      do {
        int newvalue = value * 10 + '0' - s[i++];
        if (value != newvalue / 10) { value = 0; return false; } // detect non-digits and overflow all at once
        value = newvalue;
      } while (i < s.Length);
      if (start == 0) {
        if (value == int.MinValue) { value = 0; return false; }
        value = -value;
      }
    }
    return true;
  }

  static bool TryParse(string s, out int value)        
  {
    value = 0;
    if (s == null) return false;
    s = s.Trim();
    if (s.Length == 0) return false;
    return TryParseImpl(s, (s[0] == '-')? 1: 0, ref value);
  }

Demo: http://ideone.com/PravA

回答3:

Had same problem. Try this:

static bool numParser(string s)
{
  foreach (char c in s)
    if (!char.IsNumber(c))
      return false;
  return true;
}

回答4:

public static bool IsInt(string s) {
    bool isInt = true;
    for (int i = 0; i < s.Length; i++) {
        if (!char.IsDigit(s[i])) {
            isInt = false;
            break;
        }
    }
    return isInt;
}

Example:

string int32s = "10240";
bool isInt = IsInt(int32s); // resolves true

Or:

string int32s = "1024a";
bool isInt = IsInt(int32s); // resolves false

回答5:

If your number is a string you may get the strings char array and check if Char.IsNumber is true for every char.

Check if the first char is '-' to allow for negative numbers, if you need them and add a try/catch block to protect from numbers exceeding the range (int min / max value). If you don't have to deal with numbers approaching min/max consider setting a max length (maybe 6-7 digits) and simply check string.Length instead.

If the chance you encounter only valid ints and invalid ones are rare invalid operations you may stick with a simple try/catch block (see my comment to ctackes answer).

来源：https://stackoverflow.com/questions/6563968/c-sharp-integer-validation-compactframework

标签

compact-framework