There are multiple classes that are grouped together as “numeric” classes, the 2 most common of which are double (for double precision floating point numbers) and integer. R will automatically convert between the numeric classes when needed, so for the most part it does not matter to the casual user whether the number 3 is … Read more
If you want to evaluate a string expression use the below code snippet. using System.Data; DataTable dt = new DataTable(); var v = dt.Compute(“3 * (2+4)”,””);
Update for C++11 As of the C++11 standard, string-to-number conversion and vice-versa are built in into the standard library. All the following functions are present in <string> (as per paragraph 21.5). string to numeric float stof(const string& str, size_t *idx = 0); double stod(const string& str, size_t *idx = 0); long double stold(const string& str, … Read more
a.sort(function(a,b){return a – b}) These can be confusing…. check this link out.
No, this is not possible. The key will always be converted to a string. See Property Accessor docs Property names must be strings. This means that non-string objects cannot be used as keys in the object. Any non-string object, including a number, is typecasted into a string via the toString method. > var foo = … Read more
Cast from string using float(): >>> float(‘NaN’) nan >>> float(‘Inf’) inf >>> -float(‘Inf’) -inf >>> float(‘Inf’) == float(‘Inf’) True >>> float(‘Inf’) == 1 False
In Bash, you should do your check in an arithmetic context: if (( a > b )); then … fi For POSIX shells that don’t support (()), you can use -lt and -gt. if [ “$a” -gt “$b” ]; then … fi You can get a full list of comparison operators with help test or … Read more
Note: This is an updated answer. Comments below refer to an old version which messed around with keycodes. jQuery Try it yourself on JSFiddle. There is no native jQuery implementation for this, but you can filter the input values of a text <input> with the following inputFilter plugin (supports Copy+Paste, Drag+Drop, keyboard shortcuts, context menu … Read more
This is generally done with a simple user-defined function (i.e. Roll-your-own “isNumeric” function). Something like: public static boolean isNumeric(String str) { try { Double.parseDouble(str); return true; } catch(NumberFormatException e){ return false; } } However, if you’re calling this function a lot, and you expect many of the checks to fail due to not being a … Read more
2nd October 2020: note that many bare-bones approaches are fraught with subtle bugs (eg. whitespace, implicit partial parsing, radix, coercion of arrays etc.) that many of the answers here fail to take into account. The following implementation might work for you, but note that it does not cater for number separators other than the decimal … Read more