Input string was not in a correct format Convert.ToDouble(dt.Rows[i][j].ToString())

Question

4.00/5 (1 vote)

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when I tried to compare two lines, it shows error like this:

CSS

Input string was not in a correct format.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.FormatException: Input string was not in a correct format.

My code is:

SQL

if (i != (dt.Rows.Count - 1))
{
    if (Convert.ToDouble(dt.Rows[i][1].ToString()) ==
        Convert.ToDouble(dt.Rows[i + 1][1].ToString())) // this is the wrong line
    {
        for (int j = 0; j < dt.Rows.Count - i; j++)
        {
            if (Convert.ToDouble(dt.Rows[i][1].ToString()) ==
                Convert.ToDouble(dt.Rows[i + j][1].ToString()))

I've tried also to change the ToDouble to ToInt32, but it just doesn't work.

could anyone tell me, what does this error message mean?

many thanks!!!

more codes, the dt.Rows[i][j] is something (hyperlink) databind:

C#

for (int i = 0; i < dt.Rows.Count; i++) {

              switch (dt.Rows[i][0].ToString()) {

                  case "ENTITLEMENT":
                      {
                          if (dt.Rows[i][13].ToString() != "" && dt.Rows[i][14].ToString() != "")
                          {
                              order1 = order1 + Convert.ToDouble(dt.Rows[i][14].ToString());

                              

                              double X = 0;
                              double Y = 0;
                                      if (i != (dt.Rows.Count - 1))
                                      {
                                          if (Convert.ToDouble(dt.Rows[i][1].ToString()) == Convert.ToDouble(dt.Rows[i+1][1].ToString()))
                                          {
                                              for (int j = 0; j < dt.Rows.Count - i; j++)
                                              {
                                                  if (Convert.ToDouble(dt.Rows[i][1].ToString()) == Convert.ToDouble(dt.Rows[i + j][1].ToString()))
                                                  {
                                                      X = X + Convert.ToDouble(dt.Rows[i + j][14].ToString());
                                                      Y = Y + Convert.ToDouble(dt.Rows[i + j][13].ToString());
                                                      

                                                  }
                                                  else
                                                  {
                                                      i = i + j - 1;
                                                      break;
                                                  }
                                              }
                                              if (X <= Y)
                                              {
                                                  Deliver1 = Deliver1 + X;
                                                  X = 0; Y = 0;
                                              }
                                              else
                                              {
                                                  Deliver1 = Deliver1 + Y;
                                                  X = 0; Y = 0;
                                              }
                                          }

                                          else
                                          {
                                              if (Convert.ToDouble(dt.Rows[i][13].ToString()) > Convert.ToDouble(dt.Rows[i][14].ToString()))
                                              {
                                                  Deliver1 = Deliver1 + Convert.ToDouble(dt.Rows[i][14].ToString());
                                              }
                                              else
                                                  Deliver1 = Deliver1 + Convert.ToDouble(dt.Rows[i][13].ToString());
                                          }
                                      }
                                      else if (i == (dt.Rows.Count - 1) && i > 0 && Convert.ToDouble(dt.Rows[i][1].ToString()) != Convert.ToDouble(dt.Rows[i - 1][1].ToString()))
                                      {
                                          if (Convert.ToDouble(dt.Rows[i][13].ToString()) > Convert.ToDouble(dt.Rows[i][14].ToString()))
                                          {
                                              Deliver1 = Deliver1 + Convert.ToDouble(dt.Rows[i][14].ToString());
                                          }
                                          else
                                              Deliver1 = Deliver1 + Convert.ToDouble(dt.Rows[i][13].ToString());
                                      }
                                      else if (i == (dt.Rows.Count - 1) && i == 0)
                                      {
                                          if (Convert.ToDouble(dt.Rows[i][13].ToString()) > Convert.ToDouble(dt.Rows[i][14].ToString()))
                                          {
                                              Deliver1 = Deliver1 + Convert.ToDouble(dt.Rows[i][14].ToString());
                                          }
                                          else
                                              Deliver1 = Deliver1 + Convert.ToDouble(dt.Rows[i][13].ToString());
                                      }


                          }
                              break;

                  }

Posted 28-Aug-12 2:02am

jessicachen12

Updated 28-Aug-12 2:43am

v3

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Comments

Legor 28-Aug-12 8:03am

What does the String look like?

Sarrrva 28-Aug-12 8:09am

can you show more code with table structure?
regards
sarva

pramod.hegde 28-Aug-12 8:10am

Did you try to check what does 'dt.Rows[i + 1][1].ToString()' return? Check whether it contains any Boolean value OR String OR DateTime (it fails in all these cases).

jessicachen12 28-Aug-12 8:34am

how to check the value of 'dt.Rows[i + 1][1].ToString()' ? I tried to debug, but it just doesn't work...well, there were three different people who wrote this code...however, in an other page, I use the same data and the same methode to read and it works...

the problem is I can't check the value by debuging :( horibble!!

Santhosh Kumar Jayaraman 28-Aug-12 8:44am

Check my solution

Legor 28-Aug-12 8:55am

It should be no problem to debug this. To make it easier you can just store the result of ToString() in a temporary String and look at this in the debugger. Debugging this thing is the best way to see what's not going well.

3 solutions

Solution 2

This error means:
It unable to convert the data into string type to other.
means:in some cases "dt.Rows[i + 1][1].ToString()" is returning some thing which can't convert to double.
Please what is returning "dt.Rows[i + 1][1].ToString()" using debugger. it should not return Boolean or date time so that it can't be converted to double.

Please Check

Posted 28-Aug-12 2:22am

bhagirathimfs

Updated 28-Aug-12 2:26am

v2

Solution 1

Either dt.Rows[i][1].ToString() or dt.Rows[i + 1][1].ToString() (or both) cannot be converted to double (or to Int32).
That is it does not contain a valid representation of a number.
You should debug your application to check the values of such variables.

Posted 28-Aug-12 2:13am

CPallini

Comments

Santhosh Kumar Jayaraman 28-Aug-12 8:28am

why so?

jessicachen12 28-Aug-12 8:35am

how to check the value of 'dt.Rows[i + 1][1].ToString()' ? I tried to debug, but it just doesn't work...well, there were three different people who wrote this code...however, in an other page, I use the same data and the same methode to read and it works...

the problem is I can't check the value by debuging :( horibble!!

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Santhosh Kumar Jayaraman · Accepted Answer · 2012-08-28T02:27:00

Solution 3

It means your string is not in double format. when it tried to convert into double, it couldnt and threw error.

Use Double.TryParse.

C#

double d1;
double d2;
double d3;
if(!(Double.TryParse(dt.Rows[i][1].ToString(),out d1)))
return;
if(!(Double.TryParse(dt.Rows[i+1][1].ToString(),out d2)))
return;
if (d1==d2)
{
for (int j = 0; j < dt.Rows.Count - i; j++)
        {
Double.TryParse(dt.Rows[i + j][1].ToString(),out d3);
            if (d1==d3)
{
....

Tryparse will parse the string to double only if the string contains double value. If its not able to convert, it wont threw error and stop your program. Instead of that it will set value as 0.00 if i try to convert string "s" to double in normal way, it will threw error as you said. But if i use tryparse, it will return me double.MinValue

Posted 28-Aug-12 2:27am

Santhosh Kumar Jayaraman

Updated 28-Aug-12 3:08am

v5

Comments

jessicachen12 28-Aug-12 8:45am

hi, thank you for answering. what do d1 d2 and d3 mean? sorry, I don't fully understand the TryParse method :S

Santhosh Kumar Jayaraman 28-Aug-12 8:45am

d1, d2 , d3 are local variables,

Santhosh Kumar Jayaraman 28-Aug-12 8:47am

Tryparse will parse the string to double only if the string contains double value. If its not able to convert, it wont threw error and stop your program. Instead of that it will set value as double.MinValue same as almost equal to 0 if i try to convert string "s" to double in normal way, it will threw error as you said. But if i use tryparse, it will return me Double.MinValue

Legor 28-Aug-12 8:53am

But this isn't really a solution to his problem. Just because the program doesn't crash it won't be solved.

Santhosh Kumar Jayaraman 28-Aug-12 8:56am

It will still execute if block if values are same.
If values are in double and dint match, if loop wont be executed.
If its not able to parse, it means incorrect and it will return

Legor 28-Aug-12 9:11am

Yes but the question is why it didnt parse in the first place which can be solved very easy by debugging and actually just look at the string that is going to be parsed.

Santhosh Kumar Jayaraman 28-Aug-12 9:14am

If its fixed data, then its fine. What in case if you have some value entered by user and there were no validation? Its good to use try parse always

Legor 28-Aug-12 9:20am

By the fact that the data obviously comes from a database i assume there was a validation before writing it to the database (at least lets hope so). Using tryparse maybe a good way in general but it still is no solution to the problem at hand.

jessicachen12 28-Aug-12 8:53am

I tried to use the method, and I've got an error on 'Double.TryParse(dt.Rows[i][1].ToString(),d1)': the best overloaded method match for Double.TryParse(dt.Rows[i][1].ToString(),d1) has some invalid arguments...:(

Santhosh Kumar Jayaraman 28-Aug-12 9:02am

have you declared d1 as double? post your code plz

jessicachen12 28-Aug-12 9:04am

yes, I just copied what you wrote, double d1; double d2; double d3;...

jessicachen12 28-Aug-12 9:06am

the best overloaded method match for 'Double.TryParse(string, out double)' has some invalid arguments

Santhosh Kumar Jayaraman 28-Aug-12 9:07am

my mistake include out parameter before d1.Updated solution

jessicachen12 28-Aug-12 9:21am

thanks, now there is no more error message, but it does nothing. does it mean it's unable to parse?

Santhosh Kumar Jayaraman 28-Aug-12 9:22am

yes thats right. It means incorrect data is there inside which is not of double type

Santhosh Kumar Jayaraman 28-Aug-12 9:22am

if it worked mark it as accepted

jessicachen12 28-Aug-12 9:25am

however, thanks a lot!! now i understand at least the TryParse method :)