Adding Minutes to Date is not changing the Date C# .NET

Question

double TotalMinute=300.0 double TotalMinutesAdded=1378.0

double TotalMinute=300.0
double TotalMinutesAdded=1378.0

foreach(DataRow dr in ds.Tables[0].Rows)
                {

                    //Add The above Timings to each Row's 2nd Column
                    DateTime correctDate=Convert.ToDateTime(dr[2]);

                    correctDate.AddMinutes(TotalMinute);
                    correctDate.AddMinutes(TotalMinutesAdded);

                    dr[2]=correctDate;

                }

Answer 1

DateTiem Add* functions are not supposed to change current DateTime value. They RETURN the new Value.

If you want your value changed, type like this:

correctDate = correctDate.AddMinutes(TotalMinute);

Answer 2

DateTime is immutable; functions like AddMinutes return a new DateTime; so you need to catch the returned value:

DateTime foo = ...
DateTime bar = foo.AddMinutes(5);

Answer 3

As mentioned, due to DateTime objects being immutable you have to reassign the variable.

However, a point to note is that you can chain the manipulations as so:

correctDate = correctDate.AddMinutes(TotalMinute)
                         .AddMinutes(TotalMinutesAdded);

Answer 4

您必须将correctDate变量设置为从AddMinutes调用返回的实例：

correctDate = correctDate.AddMinutes(TotalMinute);

Answer 5

DateTime is an immutable type, much like String is. You would write date = date.AddDays(1) like you would write str = str.Replace("hello", "").

Answer 6

...and to add say 5 minutes to the current time to a datetime variable:

dim dateFive_Minute_Time as datetime

dateFive_Minute_Time = Now.AddMinutes(5)

Answer 7

AddMinutes() does not change the value of the original DateTime. It returns a new DateTime with the new value that you have to assign to a variable.

Answer 8

The problem lies with

correctDate.AddMinutes(TotalMinute); 
correctDate.AddMinutes(TotalMinutesAdded);

it should be

correctDate = correctDate.AddMinutes(TotalMinute); 
correctDate = correctDate.AddMinutes(TotalMinutesAdded);

The AddMinutes method returns the result, not adding the minutes to correctDate