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String to int

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  • M Michael Bookatz

    what's the difference between the method you've used and result = int.parse("100000");

    M Offline
    M Offline
    musefan
    wrote on last edited by
    #7

    The difference is that if you pass a string to int.parse() that is not a valid string (contains noon-numeric characters) it will throw an exception that you will need to manually handle. If you use my method the error is handled automatically and the result is set to 0, its up to you if you want to handle the error yourself thou, depends how much validation control you need. if you are expecting the result could sometimes be 0 as a result then you may be best to handle the error yourself. but in the case of a port number you shouldnt need to do this, just check if result is 0 for an error.

    Life goes very fast. Tomorrow, today is already yesterday.

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    • M Michael Bookatz

      what's the difference between the method you've used and result = int.parse("100000");

      M Offline
      M Offline
      Mirko1980
      wrote on last edited by
      #8

      If the input string is not a valid integer, int.Parse throws an exception, while int.TryParse returns false without setting result value. e.g.

      string wrong = "xyz";
      result = int.Parse(wrong); // an exception is thrown here

      string wrong = "xyz";
      int result = -1;
      bool success = int.TryParse(wrong, out result); // success is false, while result will still be -1

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      • M musefan

        The difference is that if you pass a string to int.parse() that is not a valid string (contains noon-numeric characters) it will throw an exception that you will need to manually handle. If you use my method the error is handled automatically and the result is set to 0, its up to you if you want to handle the error yourself thou, depends how much validation control you need. if you are expecting the result could sometimes be 0 as a result then you may be best to handle the error yourself. but in the case of a port number you shouldnt need to do this, just check if result is 0 for an error.

        Life goes very fast. Tomorrow, today is already yesterday.

        M Offline
        M Offline
        Michael Bookatz
        wrote on last edited by
        #9

        Thank you for the reply... next time I convert I'll bare it in mind.

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        • M Mirko1980

          If the input string is not a valid integer, int.Parse throws an exception, while int.TryParse returns false without setting result value. e.g.

          string wrong = "xyz";
          result = int.Parse(wrong); // an exception is thrown here

          string wrong = "xyz";
          int result = -1;
          bool success = int.TryParse(wrong, out result); // success is false, while result will still be -1

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          M Offline
          Michael Bookatz
          wrote on last edited by
          #10

          Thanks for the reply, however according to the above post the result would be set to zero and not stay at -1 or is it only set to zero if there is no valid number in it?

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          • M Michael Bookatz

            Thanks for the reply, however according to the above post the result would be set to zero and not stay at -1 or is it only set to zero if there is no valid number in it?

            M Offline
            M Offline
            Mirko1980
            wrote on last edited by
            #11

            Yes, I was wrong, int.TryParse puts 0 in the result if the parsing fails. For some reason, I tought that the resul value was unchanged in case of failure, my bad.

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            • M musefan

              The difference is that if you pass a string to int.parse() that is not a valid string (contains noon-numeric characters) it will throw an exception that you will need to manually handle. If you use my method the error is handled automatically and the result is set to 0, its up to you if you want to handle the error yourself thou, depends how much validation control you need. if you are expecting the result could sometimes be 0 as a result then you may be best to handle the error yourself. but in the case of a port number you shouldnt need to do this, just check if result is 0 for an error.

              Life goes very fast. Tomorrow, today is already yesterday.

              D Offline
              D Offline
              DaveyM69
              wrote on last edited by
              #12

              musefan wrote:

              just check if result is 0 for an error

              Better to assign and check the boolean return value of the TryParse method before working with the value. Still preferable to catching an exception!

              Dave
              BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
              Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

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              • M Mirko1980

                Yes, I was wrong, int.TryParse puts 0 in the result if the parsing fails. For some reason, I tought that the resul value was unchanged in case of failure, my bad.

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                Michael Bookatz
                wrote on last edited by
                #13

                No worries thanks for the clarification

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                • M Michael Bookatz

                  Thanks for the reply, however according to the above post the result would be set to zero and not stay at -1 or is it only set to zero if there is no valid number in it?

                  D Offline
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                  DaveyM69
                  wrote on last edited by
                  #14

                  hopingToCode wrote:

                  only set to zero if there is no valid number

                  ... or if the number in the text is zero! Check the return value of the TryParse method to determine if successful.

                  Dave
                  BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
                  Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

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                  • D DaveyM69

                    musefan wrote:

                    just check if result is 0 for an error

                    Better to assign and check the boolean return value of the TryParse method before working with the value. Still preferable to catching an exception!

                    Dave
                    BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
                    Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

                    M Offline
                    M Offline
                    musefan
                    wrote on last edited by
                    #15

                    Ahh yes, i forgot TryParse() returns a bool

                    Life goes very fast. Tomorrow, today is already yesterday.

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                    • G Greg Chelstowski

                      If I might... Is it considered really bad practice to do Convert.ToInt32 ? I have seen stuff (and well, I have used it, too) like:

                      string x = "10";
                      int xInt;
                      try
                      {
                      xInt = Convert.ToInt32(x);
                      }
                      catch
                      {
                      xInt = 0;
                      }

                      Would that not do the same as TryParse? Or is it an unnecessary way around it, or simply, crap?

                      var question = (_2b || !(_2b));

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                      DaveyM69
                      wrote on last edited by
                      #16

                      Not bad practice, possibly a little slower going via the Convert class but I would have to check the implementation to be sure. The convert class is great for converting from a built in type to another (not just from string), but I would guess the Int32.Parse or Int32.TryParse methods would be perhaps a little more efficient.

                      Dave
                      BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
                      Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

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