检查时间跨度

Question

I have a method that queries active directory, and returns the value of the Last Password Reset to a local variable. I am trying to compare that value to the current date and time, and check if it's been less than 24 hours. I think I'm close, but can't seem to get this to work.

Thanks, Jason

string passwordLastSet = string.Empty;
passwordLastSet = DateTime.FromFileTime((Int64)(result.Properties["PwdLastSet"][0])).ToString();  
public string lastReset(DateTime pwordLastReset)
{
    if (DateTime.Now.AddHours(24) <= passwordLastSet)
    {
        return "try again later";
    }
    else
    {
        return "all is good";
    }
}

Answer 1

I am trying to compare that value to the current date and time, and check if it's been less than 24 hours.

This code almost writes itself.

DateTime timeOfLastPasswordReset = // get time of last password reset
DateTime now = DateTime.Now;
TimeSpan difference = now.Subtract(timeOfLastPasswordReset);
if(difference < TimeSpan.FromHours(24)) {
    // password was reset less than twenty-four hours ago
}
else {
    // password was reset no less than twenty-four hours ago
}

Note how the code reads exactly as you specified in English.

Answer 2

This:

 if (DateTime.Now.AddHours(24) <= passwordLastSet)

should be

   if (DateTime.Now <= passwordLastSet.AddHours(24))

Answer 3

How about (assuming I've read your intentions correctly):

// Does passwordLastSet, with 24 hours added to it, fall before or after DateTime.Now?
// If AFTER, then reject, if BEFORE, then accept
if (passwordLastSet.Add(new TimeSpan(24, 0, 0)) > DateTime.Now)
{
    // Password was last set within the last 24 hours
    return "try again later";
}
else
{
    return "all is good";
}

Answer 4

尝试DateTime.Now.AddHours(-24) <= passwordLastSet因为你想模拟现在是过去 24 小时，而不是未来

Answer 5

You are comparing a string variable and a datetime variable, it is not possible to compare them

 DateTime passwordLastSet = DateTime.FromFileTime((Int64)(result.Properties["PwdLastSet"][0]));  
 public string lastReset(DateTime pwordLastReset)
 {
     if (DateTime.Now.AddHours(24) <= passwordLastSet)
     {
         return "try again later";
     }
     else
     {
         return "all is good";
     }
 }

Change your string to DateTime if you want to compare it with current time.

Just use this

if (DateTime.Now <= passwordLastSet)
{
    return "try again later";
}
else
{
    return "all is good";
}

If you want to check it greater than 24 change both to TimeSpan and compare it.

Answer 6

if (DateTime.Now.Subtract(passwordLastSet).TotalHours < 24)
    Console.WriteLine("Try again");
else
    Console.WriteLine("all is good");

You can also use TotalDays < 1

Answer 7

To be pedantic:

• You need to check for special cases before converting to DateTime - for example pwdLastSet can be zero , so you should check this before attempting to convert.

• pwdLastSet is stored as UTC - so that converting to local time using DateTime.FromFileTime might return an ambiguous time .

  So it would be better to use DateTime.FromFileTimeUtc and compare with DateTime.UtcNow .

Depending on exactly what you want to achieve, you may also want to check the userAccountControl flags - something like the following (untested):

    [Flags]
    private enum AdsUserFlags
    {
        Script = 0x1,
        AccountDisabled = 0x2,
        HomeDirectoryRequired = 0x8,
        AccountLockedOut = 0x10,
        PasswordNotRequired = 0x20,
        PasswordCannotChange = 0x40,
        EncryptedTextPasswordAllowed = 0x80,
        TempDuplicateAccount = 0x100,
        NormalAccount = 0x200,
        InterDomainTrustAccount = 0x800,
        WorkstationTrustAccount = 0x1000,
        ServerTrustAccount = 0x2000,
        PasswordDoesNotExpire = 0x10000,
        MnsLogonAccount = 0x20000,
        SmartCardRequired = 0x40000,
        TrustedForDelegation = 0x80000,
        AccountNotDelegated = 0x100000,
        UseDesKeyOnly = 0x200000,
        DontRequirePreauth = 0x400000,
        PasswordExpired = 0x800000,
        TrustedToAuthenticateForDelegation = 0x1000000,
        NoAuthDataRequired = 0x2000000
    }

    ...
    AdsUserFlags userAccountControl = (AdsUserFlags)result.Properties["userAccountControl"][0];
    long lastReset = (long)result.Properties["PwdLastSet"][0];

    if (lastReset == 0L)
    {
        if ((userAccountControl & AdsUserFlags.PasswordDoesNotExpire) == 0)
        {
            // ... user must set password at next login
        }
        else
        {
            // ... presumably password has never been reset
        }
    }
    else
    {
        DateTime lastResetUtc = DateTime.FromFileTimeUtc(lastReset);
        // ... etc - compare with DateTime.UtcNow
    }