Here’s a blog post describing the creation of an IsInteger UDF. Basically, it recommends adding ‘.e0’ to the value and using IsNumeric. In this way, anything that already had a decimal point now has two decimal points, causing IsNumeric to be false, and anything already expressed in scientific notation is invalidated by the e0.
Below is an extension method that will allow you to write code like this: int id = request.QueryString.GetValue<int>(“id”); DateTime date = request.QueryString.GetValue<DateTime>(“date”); It makes use of TypeDescriptor to perform the conversion. Based on your needs, you could add an overload which takes a default value instead of throwing an exception: public static T GetValue<T>(this NameValueCollection … Read more
REGEXP_LIKE(column, ‘^[[:digit:]]+$’) returns TRUE if column holds only numeric characters
You can use the T-SQL functions TRY_CAST() or TRY_CONVERT() if you’re running SQL Server 2012 as Bacon Bits mentions in the comments: SELECT CASE WHEN TRY_CAST(‘foo’ AS INT) IS NULL THEN 0 ELSE 1 END SELECT CASE WHEN TRY_CAST(1 AS INT) IS NULL THEN 0 ELSE 1 END If you’re using SQL 2008 R2 or … Read more
If you want to restrict input (as opposed to validation), you could work with the key events. something like this: <input type=”text” class=”numbersOnly” value=”” /> And: jQuery(‘.numbersOnly’).keyup(function () { this.value = this.value.replace(/[^0-9\.]/g,”); }); This immediately lets the user know that they can’t enter alpha characters, etc. rather than later during the validation phase. You’ll still … Read more
int n; bool isNumeric = int.TryParse(“123”, out n); Update As of C# 7: var isNumeric = int.TryParse(“123”, out int n); or if you don’t need the number you can discard the out parameter var isNumeric = int.TryParse(“123”, out _); The var s can be replaced by their respective types!