Numeric Value

Question

How to know whether a TextBox.Text Value is a number? I mean how to know if TextBox is having 1234 or is having ABCD? May be is easy but I'm a begginer. Sorry. Thanx in advance.

Carlos Sanchez · Answer

Thanks everybody. The most of the solutions are similar. Regular expressions are interesting I will use them in many others situations and I'll replace several parts of my code. Thank you. Carlos

Mykonine · Answer

I use this one: bool isNumber = true; try { int n = int.Parse(textBox1.Text); } catch { isNumber = false; }

asic · Answer

hi this is  regular expression ^ means: matches the position in the start of the string [0-9] means: match the range of numbers of the range 0:9 ........... $ means: match this at the end of the string the hole statement means match that the string characters from start till end equal to 0-9 only numbers but this way is complicated for my opinion .........use any methode other people said in the first they are enough ............... thanks

Carlos Sanchez · Answer

What it means ^[0-9]+$ n' what else you can do with this? Can you explain some more about it? Thanx everybody.

jcity444 · Answer

Also you can use regular expressions using System.Text.RegularExpressions; .... Regex expression = new Regex(^[0-9]+$); if (expression.Match(textBox1.Text).Success == false) { MessageBox.Show(not a number!); } -Mike G.

supersonic_skymaster · Answer

whoops there is an error. instead of || in the if statement replace that with &&.

supersonic_skymaster · Answer

A way that I usually used to see whether there letters is: private bool IsAlpha( string strToCheck ) { bool Valid = true; foreach( char c in strToCheck ) { if ( !( c >= 65 && c = 97 && c <= 122 ) ) { Valid = false; break; } } return Valid; } 65 through 90 are the ascii code for the capital letters. 97 through 122 are the ascii code for the lower case letters.

Carlos Sanchez · Answer

Is a good method. thanx jamesdivine.

james · Answer

there may be a better way but this is what I've used in the past private bool IsNumeric(object myobject) { bool tmpbool = true; try { int tmpint = Convert.ToInt32(myobject); } catch(Exception) { tmpbool = false; } return tmpbool; }