Double TryParse or Convert ToDouble - which is faster and safer

Question

My application reads an Excel file using VSTO and adds the read data to a StringDictionary  It adds only data that are numbers with a few digits  1000 1000 2 1000 34 - comma is a delimiter in Russian standards    What is better to check if the current string is an appropriate number   object data  string key     data had read  try     Convert ToDouble regionData  CultureInfo CurrentCulture     dic Add key  regionData ToString       catch  InvalidCastException         is not a number     or  double d  string str   data ToString    if  Double TryParse str  out d      if done  then is a number     dic Add key  str       I have to use StringDictionary instead of Dictionary lt string  double gt  because of the following parsing algorithm issues   My questions  Which way is faster  Which is safer   And is it better to call Convert ToDouble object  or Convert ToDouble string

User · Answer

To start with  I d use double Parse rather than Convert ToDouble in the first place   As to whether you should use Parse or TryParse  can you proceed if there s bad input data  or is that a really exceptional condition  If it s exceptional  use Parse and let it blow up if the input is bad  If it s expected and can be cleanly handled  use TryParse

User · Answer

I generally try to avoid the Convert class  meaning  I don t use it  because I find it very confusing  the code gives too few hints on what exactly happens here since Convert allows a lot of semantically very different conversions to occur with the same code  This makes it hard to control for the programmer what exactly is happening   My advice  therefore  is never to use this class  It s not really necessary either  except for binary formatting of a number  because the normal ToString method of number classes doesn t offer an appropriate method to do this

User · Answer

If you aren t going to be handling the exception go with TryParse   TryParse is faster because it doesn t have to deal with the whole exception stack trace

User · Answer

Unless you are 100  certain of your inputs  which is rarely the case  you should use Double TryParse   Convert ToDouble will throw an exception on non-numbers Double Parse will throw an exception on non-numbers or null Double TryParse will return false or 0 on any of the above without generating an exception    The speed of the parse becomes secondary when you throw an exception because there is not much slower than an exception

User · Answer

I did a quick non-scientific test in Release mode  I used two inputs   2 34523  and  badinput  into both methods and iterated 1 000 000 times   Valid input   Double TryParse   646ms Convert ToDouble   662 ms   Not much different  as expected  For all intents and purposes  for valid input  these are the same   Invalid input   Double TryParse   612ms Convert ToDouble        Well   it was running for a long time  I reran the entire thing using 1 000 iterations and Convert ToDouble with bad input took 8 3 seconds  Averaging it out  it would take over 2 hours  I don t care how basic the test is  in the invalid input case  Convert ToDouble s exception raising will ruin your performance   So  here s another vote for TryParse with some numbers to back it up

User · Answer

I have always preferred using the TryParse   methods because it is going to spit back success or failure to convert without having to worry about exceptions

User · Answer

The  NET Framework design guidelines recommend using the Try methods  Avoiding exceptions is usually a good idea   Convert ToDouble object  will do   IConvertible  object  ToDouble null    Which will call Convert ToDouble string  null   So it s faster to call the string version   However  the string version just does this   if  value    null        return 0 0    return double Parse value  NumberStyles Float   NumberStyles AllowThousands  provider     So it s faster to do the double Parse directly

User · Answer

Lots of hate for the Convert class here     Just to balance a little bit  there is one advantage for Convert - if you are handed an object   Convert ToDouble o     can just return the value easily if o is already a Double  or an int or anything readily castable    Using Double Parse or Double TryParse is great if you already have it in a string  but  Double Parse o ToString       has to go make the string to be parsed first and depending on your input that could be more expensive

User · Answer

Personally  I find the TryParse method easier to read  which one you ll actually want to use depends on your use-case  if errors can be handled locally you are expecting errors and a bool from TryParse is good  else you might want to just let the exceptions fly   I would expect the TryParse to be faster too  since it avoids the overhead of exception handling  But use a benchmark tool  like Jon Skeet s MiniBench to compare the various possibilities

User · Answer

This is an interesting old question  I m adding an answer because nobody noticed a couple of things with the original question   Which is faster  Convert ToDouble or Double TryParse  Which is safer  Convert ToDouble or Double TryParse   I m going to answer both these questions  I ll update the answer later   in detail  but first   For safety  the thing every programmer missed in this question is the line  emphasis mine       It adds only data that are numbers with a few digits  1000 1000 2 1000 34 - comma is a delimiter in Russian standards     Followed by this code example   Convert ToDouble regionData  CultureInfo CurrentCulture     What s interesting here is that if the spreadsheets are in Russian number format but Excel has not correctly typed the cell fields  what is the correct interpretation of the values coming in from Excel   Here is another interesting thing about the two examples  regarding speed   catch  InvalidCastException           is not a number     This is likely going to generate MSIL that looks like this   catch  mscorlib System InvalidCastException      IL 0023   stloc 0   IL 0024   nop   IL 0025   ldloc 0   IL 0026   nop   IL 002b   nop   IL 002c   nop   IL 002d   leave s    IL 002f       end handler IL 002f  nop IL 0030  return   In this sense  we can probably compare the total number of MSIL instructions carried out by each program - more on that later as I update this post   I believe code should be Correct  Clear  and Fast    In that order

User · Answer

Double TryParse IMO   It is easier for you to handle  You ll know exactly where the error occurred   Then you can deal with it how you see fit if it returns false  i e could not convert

[c#] Double.TryParse or Convert.ToDouble - which is faster and safer?

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