比较日期大于 C#

Question

I'm trying to check if the passing variable date is greater than a static date which I have included in the code and currently trying to use the following code,

private String LastPayDate {
  get { 
    string foo;

    if(Parameters.TryGetValue("Last Pay Date", out foo))
      return foo;
    else 
      return null; 
  } 
}

private Boolean IsLastPay() {
  if (!string.IsNullOrEmpty(LastPayDate)) {
    if(DateTime.Parse(Parameters.TryGetValue("Last Pay Date") >="24/05/2018")
       return true;
    else
      return false;
  } 

  return false;
}   

however the only error I get is within below code section,

if(DateTime.Parse(Parameters.TryGetValue("Last Pay Date") > "24/05/2018")

can anyone help please ?

Answer 1

If you want to compare DateTime s, compare them, but not string s:

//TODO: what is the magic number (date) 24 May 2018?
private Boolean IsLastPay() {
  if (Parameters.TryGetValue("Last Pay Date", out var dateSt))
    if (DateTime.TryParse(dateSt, out var paramDate))
      return paramDate >= new DateTime(2018, 5, 24);
    else
      return false; // DateTime.TryParse failed to parse the parameter
  else
    return false;   // Parameters.TryGetValue failed to get the value
}

Answer 2

Thank you for respond. It did helped and I've managed to use below code and its working now, Much appreciate Help!

private Boolean IsLastPay()
{
   if (!string.IsNullOrEmpty(LastPayDate))
{
   string lpd;
}
   if(Parameters.TryGetValue("Last Pay Date", out lpd))
{
   if(DateTime.Parse(lpd) > new DateTime(2018,05,24))
       return true;
   else
       return false;
}
}
return false;
}

Answer 3

Why not use the DateTime.Compare() method of DateTime class. For this you need to have both the variables/objects of type DateTime .

string staticDate = "24/05/2018"; //dd-MM-yyyy
string inputDate = "14/08/20"; //dd-MM-yy
string greaterDate = CalculateGreaterDate(inputDate, staticDate); // 14/08/20 is greater  

public static string CalculateGreaterDate(string iDate, string sDate)
{
   // input date
   string input = iDate;
   var inputElements = input.Split('/');
   int inputDay = Convert.ToInt32(inputElements[0]); //14 
   int inputMonth = Convert.ToInt32(inputElements[1]); //08
   int inputYear = Convert.ToInt32(inputElements[2]); //20

   // static date
   string static = sDate;
   var staticElements = static.Split('/');
   int staticDay = Convert.ToInt32(staticElements[0]); //24
   int staticMonth = Convert.ToInt32(staticElements[1]); //05
   int staticYear = Convert.ToInt32(staticElements[2]); //2018

   DateTime inputDate = new DateTime(inputYear, inputMonth, inputDay);
   DateTime staticDate = new DateTime(staticYear, staticMonth, staticDay);

   // DateTime.Compare(d1, d2) returns:
   // > 0 : d1 is greater than d2
   // = 0 : d1 & d2 are equal
   // < 0 : d1 is smaller than d2
   int result = DateTime.Compare(inputDate, staticDate);
   if (result > 0)
      return iDate + " is greater";
   else if (result < 0)
      return sDate + " is greater";
   else if (result == 0)
      return iDate + " is equal to " + sDate;
}