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Validation IsNumeric in C#

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  • A alwz_nikhil

    Use this public bool IsNumeric(string s) { try { Int32.Parse(s); } catch { return false; } return true; } Nikhil

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    angelagke
    wrote on last edited by
    #5

    Thanks for your source code :) just now i also found another way to validate the numeric field, I would like to share it with you : public bool chkNumeric(string strText) { char[] chars = strText.ToCharArray(); for (int i = 0; i < chars.Length; i++) { if (chars[i] > 57 || chars[i] < 48) { return false; } } return true; } angela

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    • A angelagke

      Thanks for your source code :) just now i also found another way to validate the numeric field, I would like to share it with you : public bool chkNumeric(string strText) { char[] chars = strText.ToCharArray(); for (int i = 0; i < chars.Length; i++) { if (chars[i] > 57 || chars[i] < 48) { return false; } } return true; } angela

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      Shajeel
      wrote on last edited by
      #6

      this code wil not handle -ve numbers and number exceeding int max limit Regards Shajeel

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      • A angelagke

        How to check validation numeric field in C# coz C# doesn't has built-in IsNumeric function :( Angela

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        rfjeld
        wrote on last edited by
        #7

        Well you could just do like this: try { Convert.ToInt32(txtstring); } catch { MessageBox.Show("You must input a numeric value!"); return; } -- modified at 2:53 Thursday 8th June, 2006

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        • R rfjeld

          Well you could just do like this: try { Convert.ToInt32(txtstring); } catch { MessageBox.Show("You must input a numeric value!"); return; } -- modified at 2:53 Thursday 8th June, 2006

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          Mairaaj Khan
          wrote on last edited by
          #8

          And whats about this... if(!char.IsNumber(e.KeyChar) e.Handled=true; write it in the text control's KeyPress event. _____________________________ Success is not something to wait for, its something to work for.

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          • A angelagke

            How to check validation numeric field in C# coz C# doesn't has built-in IsNumeric function :( Angela

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            Dave Doknjas
            wrote on last edited by
            #9

            A couple of notes about the other replies: 1. You don't want to be catching exceptions as part of the normal logic flow. This is a well-accepted standard in software development. 2. You don't want to do this in a KeyPress event since that won't handle pasting code from another source. For a more robust equivalent to VB's IsNumeric method see: http://www.tangiblesoftwaresolutions.com/Articles/CSharp%20Equivalent%20to%20IsNumeric.htm[^] David Anton www.tangiblesoftwaresolutions.com Instant C#: VB to C# converter Instant VB: C# to VB converter Instant C++: C# to C++ converter Instant C++: VB to C++ converter Clear VB: Cleans up VB.NET code

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            • D Dave Doknjas

              A couple of notes about the other replies: 1. You don't want to be catching exceptions as part of the normal logic flow. This is a well-accepted standard in software development. 2. You don't want to do this in a KeyPress event since that won't handle pasting code from another source. For a more robust equivalent to VB's IsNumeric method see: http://www.tangiblesoftwaresolutions.com/Articles/CSharp%20Equivalent%20to%20IsNumeric.htm[^] David Anton www.tangiblesoftwaresolutions.com Instant C#: VB to C# converter Instant VB: C# to VB converter Instant C++: C# to C++ converter Instant C++: VB to C++ converter Clear VB: Cleans up VB.NET code

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              Mairaaj Khan
              wrote on last edited by
              #10

              David Anton wrote:

              2. You don't want to do this in a KeyPress event since that won't handle pasting code from another source.

              Hi David Anton I didn't understand this point! _____________________________ Success is not something to wait for, its something to work for.

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              • A angelagke

                How to check validation numeric field in C# coz C# doesn't has built-in IsNumeric function :( Angela

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                Suamal
                wrote on last edited by
                #11

                this code may help you to check whether the given value is numeric or not using System.Text.RegularExpressions; public static bool CheckNumeric(string strText) { return CheckRegExPattern(@"^[0-9]+$", strText.Trim()); } -- modified at 7:05 Friday 9th June, 2006

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                • M Mairaaj Khan

                  David Anton wrote:

                  2. You don't want to do this in a KeyPress event since that won't handle pasting code from another source.

                  Hi David Anton I didn't understand this point! _____________________________ Success is not something to wait for, its something to work for.

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                  Dave Doknjas
                  wrote on last edited by
                  #12

                  Standard Windows copy/paste doesn't trigger KeyPress events. User the TextChanged event to capture pasting of text also. David Anton www.tangiblesoftwaresolutions.com Instant C#: VB to C# converter Instant VB: C# to VB converter Instant C++: C# to C++ converter Instant C++: VB to C++ converter Clear VB: Cleans up VB.NET code

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                  • A angelagke

                    Thanks for your source code :) just now i also found another way to validate the numeric field, I would like to share it with you : public bool chkNumeric(string strText) { char[] chars = strText.ToCharArray(); for (int i = 0; i < chars.Length; i++) { if (chars[i] > 57 || chars[i] < 48) { return false; } } return true; } angela

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                    Dustin Metzgar
                    wrote on last edited by
                    #13

                    You're kidding right?

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                    • A alwz_nikhil

                      Use this public bool IsNumeric(string s) { try { Int32.Parse(s); } catch { return false; } return true; } Nikhil

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                      Dustin Metzgar
                      wrote on last edited by
                      #14

                      Be careful. The exception police will get you. As has been explained to me, relying on exceptions is bad practice. Use TryParse instead of Parse and it returns a boolean to let you know if it worked or not.

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                      • D Dave Doknjas

                        Standard Windows copy/paste doesn't trigger KeyPress events. User the TextChanged event to capture pasting of text also. David Anton www.tangiblesoftwaresolutions.com Instant C#: VB to C# converter Instant VB: C# to VB converter Instant C++: C# to C++ converter Instant C++: VB to C++ converter Clear VB: Cleans up VB.NET code

                        M Offline
                        M Offline
                        Mairaaj Khan
                        wrote on last edited by
                        #15

                        David Anton wrote:

                        Standard Windows copy/paste doesn't trigger KeyPress events. User the TextChanged event to capture pasting of text also.

                        of course! I checked it last day and found the same situation. It means that we can't rely on only keyPress event for validation, we have to check some other events too; like, as you mentioned, TextChanged etc. Thanks. _____________________________ Success is not something to wait for, its something to work for.

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                        • S Suamal

                          this code may help you to check whether the given value is numeric or not using System.Text.RegularExpressions; public static bool CheckNumeric(string strText) { return CheckRegExPattern(@"^[0-9]+$", strText.Trim()); } -- modified at 7:05 Friday 9th June, 2006

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                          Mairaaj Khan
                          wrote on last edited by
                          #16

                          Suamal wrote:

                          CheckRegExPattern

                          What is this? I didn't find it.

                          Suamal wrote:

                          using System.Text.RegularExpressions; public static bool CheckNumeric(string strText) { return CheckRegExPattern(@"^[0-9]+$", strText.Trim()); }

                          While taking idea from this I tryed to implement it like this: using System.Text.RegularExpressions; public bool CheckNumeric(string strtext) { System.Text.RegularExpressions.Regex rr = new Regex(@"^[0-9]+$"); return rr.IsMatch(strtext); } ///In Button click event MessageBox.Show(this.CheckNumeric(TextBox1.Text).ToString()); Its working, but i'm unable to interpret this @"^[0-9]+$" Thanks and Best Regards _____________________________ Success is not something to wait for, its something to work for.

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                          • M Mairaaj Khan

                            Suamal wrote:

                            CheckRegExPattern

                            What is this? I didn't find it.

                            Suamal wrote:

                            using System.Text.RegularExpressions; public static bool CheckNumeric(string strText) { return CheckRegExPattern(@"^[0-9]+$", strText.Trim()); }

                            While taking idea from this I tryed to implement it like this: using System.Text.RegularExpressions; public bool CheckNumeric(string strtext) { System.Text.RegularExpressions.Regex rr = new Regex(@"^[0-9]+$"); return rr.IsMatch(strtext); } ///In Button click event MessageBox.Show(this.CheckNumeric(TextBox1.Text).ToString()); Its working, but i'm unable to interpret this @"^[0-9]+$" Thanks and Best Regards _____________________________ Success is not something to wait for, its something to work for.

                            M Offline
                            M Offline
                            Mairaaj Khan
                            wrote on last edited by
                            #17

                            At last found the site .NET Framework Regular Expressions [^] Thanks God and Thanks to the forum _____________________________ Success is not something to wait for, its something to work for.

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