Problem in loop in datagridview in C#

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I Try a Code for Automatic Add Months Loop in my DataGridView in C#
Code Work Fine when i use Date 1 to 28 like (15/12/2020, 25/01/2020)
But I have Problem when i use 29 to 30 or 31 i have a Problem
For Example
My Code Result:---

Date1 15/07/2020(Work Fine)   Date2 30/07/2020(Problem)    Date3 31/07/2020(Problem)
  Result(Date1)   ......       Result(Date2)..........            Result (Date3)
15/08/2020      ........       30/08/2020 ............                    31/08/2020
15/09/2020      ........       30/09/2020 ............                    30/09/2020
15/10/2020      ........       30/10/2020 ............                    30/10/2020(P)
15/11/2020      ........       30/11/2020 ............                    30/11/2020
15/12/2020      ........       30/12/2020 ............                    30/12/2020(P)
15/01/2021      ........       30/01/2021 ............                    30/01/2021(P)
15/02/2021      ........       28/02/2021 ............                    28/02/2021(P)
15/03/2021      ........       28/03/2021(P)........                  28/03/2021(P) 
15/04/2021      ........       28/04/2021(P)........                  28/03/2021(P)
15/05/2021      ........       28/05/2021(P)........                  28/03/2021(P)
15/06/2021      ........       28/06/2021(P)........                  28/03/2021(P)
15/07/2021      ........       28/07/2021(P)........                  28/03/2021(P)

What I have tried:

My Code is

C#

private void LoadDate()
{
    DateTime dt=Convert.ToDateTime(textBoxLoanDate.Text);
    for (int i = 0; i < 1; i++)
    foreach (DataGridViewRow row in dataGridView1.Rows)
    {
        dt = dt.AddMonths(1);
        row.Cells["Date"].Value = dt.ToString("dd/MM/yyyy");
        
    }
}

Please Help me Solve this Problem

Posted 3-Mar-20 21:05pm

Amar chand123

Updated 3-Mar-20 23:51pm

Tomas Takac

v2

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Comments

OriginalGriff 4-Mar-20 3:24am

What problem?
What does it do that you didn't expect, or not do that you did?
Are there any error messages, and if so, what are they, and where do they happen?

Use the "Improve question" widget to edit your question and provide better information.

Amar chand123 4-Mar-20 5:34am

there is no Error Message Problem is When i use loop Month then as you see when i use (Date1) Loop Code Work is Fine, but when i use ( Date2 or 3 ) my loop code not work Properly ( if i use date 31/12/2020 then after 28th February my code change date 28/03/2021, 28/04/2021, 28/05/2021 but i need this Result 31/03/2021, 30/04/2021, 31/05/2021

2 solutions

Solution 2

Quote:
there is no Error Message Problem is When i use loop Month then as you see when i use (Date1) Loop Code Work is Fine, but when i use ( Date2 or 3 ) my loop code not work Properly ( if i use date 31/12/2020 then after 28th February my code change date 28/03/2021, 28/04/2021, 28/05/2021 but i need this Result 31/03/2021, 30/04/2021, 31/05/2021

The safest way to do that is take the first of month you want the last day of, add one month, and subtract one day. That always gives you the last day of that month, regardless of how many days it contains and what your original start date was.
This may help: DateTime Extensions to Make Some Simple Tasks a Little More Readable[^]

Posted 3-Mar-20 23:51pm

OriginalGriff

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Tomas Takac · Accepted Answer · 2020-03-03T21:31:00

Solution 1

The problem is that you are using the previous date and then adding one month to it. If you instead take the start date and always add a number of months to it the sequence will be correct:

C#

var start = new DateTime(2020, 8, 30);
for (int i = 0; i < 10; i++)
{
	Console.WriteLine(start.AddMonths(i).ToString("dd/MM/yyyy"));
}

The result:

In your code:

C#

private void LoadDate()
{
    DateTime dt=Convert.ToDateTime(textBoxLoanDate.Text);
    var monthCounter = 1;
    foreach (DataGridViewRow row in dataGridView1.Rows)
    {
        row.Cells["Date"].Value = dt.AddMonths(monthCounter).ToString("dd/MM/yyyy");
        monthCounter++;       
    }
}

Posted 3-Mar-20 21:31pm

Tomas Takac

Updated 4-Mar-20 0:53am

v3

Comments

Amar chand123 4-Mar-20 5:23am

Sir Tomas Takac
how to use this code in my Code, can you modify my code because i am is beginner in Programming, thank you

Tomas Takac 4-Mar-20 5:46am

I updated my answer with your code, how it should look like. But you need to understand the concepts and be able to apply them in different situation.

Amar chand123 4-Mar-20 6:10am

Sir, if i use Date 31/08/2020 in your Code then i Result Show---
30/09/2020
30/11/2020
28/02/2021
28/06/2021
28/11/2021
28/05/2022
28/12/2022
28/08/2023

Tomas Takac 4-Mar-20 6:53am

My bad, I fixed the bug, check again.

Amar chand123 4-Mar-20 7:42am

Thank you for help Sir
this code work Fine and sir can you explain me what Problem in your previous Code for my Future reference

Tomas Takac 4-Mar-20 7:53am

dt = dt.AddMonths(monthCounter) - this was modifying the original variable, the trick is to preserve original value of dt and add number of months to it.

Amar chand123 4-Mar-20 8:02am

Thank you