is-empty

Is there a way to check strings for nil and "" in Swift? In Rails, I can use blank() to check. I currently have this, but it seems overkill: if stringA? != nil { if !stringA!.isEmpty { ...blah blah } } If you're dealing with optional Strings, this works: (string ?? "").isEmpty The ?? nil coalescing operator returns the left side if it's non-nil, otherwise it returns the right side. You can also use it like this to return a default value: (string ?? "").isEmpty ? "Default" : string! Ryan You could perhaps use the if-let-where clause: Swift 3: if let string = string, !string.isEmpty { /* string

I have two ways of checking if a List is empty or not if (CollectionUtils.isNotEmpty(listName)) and if (listName != null && listName.size() != 0) My arch tells me that the former is better than latter. But I think the latter is better. Can anyone please clarify it? Jon Skeet You should absolutely use isEmpty() . Computing the size() of an arbitrary list could be expensive. Even validating whether it has any elements can be expensive, of course, but there's no optimization for size() which can't also make isEmpty() faster, whereas the reverse is not the case. For example, suppose you had a

I have an object and within it I wanna check if some properties is set to false, like: If (not objresult.EOF) Then 'Some code End if But somehow, sometimes objresult.EOF is Empty , and how can I check it? IsEmpty function is for excel cells only objresult.EOF Is Nothing - return Empty objresult.EOF <> null - return Empty as well! Oorang How you test depends on the Property's DataType: | Type | Test | Test2 | Numeric (Long, Integer, Double etc.) | If obj.Property = 0 Then | | Boolen (True/False) | If Not obj.Property Then | If obj.Property = False Then | Object | If obj.Property Is Nothing Then

How can I check if a variable is empty in Bash? Jay In bash at least the following command tests if $var is empty : if [[ -z "$var" ]]; then #do what you want fi The command man test is your friend. ChristopheD Presuming bash: var="" if [ -n "$var" ]; then echo "not empty" else echo "empty" fi Daniel Andersson I have also seen if [ "x$variable" = "x" ]; then ... which is obviously very robust and shell independent. Also, there is a difference between "empty" and "unset". See How to tell if a string is not defined in a bash shell script? . alexli if [ ${foo:+1} ] then echo "yes" fi prints yes

Is there a JavaScript equivalent to .NET's String.IsNullOrWhitespace so that I can check if a textbox on the client-side has any visible text in it? I'd rather do this on the client-side first than post back the textbox value and rely only on server-side validation, even though I will do that as well. It's easy enough to roll your own : function isNullOrWhitespace( input ) { if (typeof input === 'undefined' || input == null) return true; return input.replace(/\s/g, '').length < 1; } For a succinct modern cross-browser implementation, just do: function isNullOrWhitespace( input ) { return

I have a file called diff.txt. Want to check if it is empty. Did something like this but couldn't get it working. if [ -s diff.txt ] then touch empty.txt rm full.txt else touch full.txt rm emtpy.txt fi Misspellings are irritating, aren't they? Check your spelling of empty , but then also try this: #!/bin/bash -e if [ -s diff.txt ] then rm -f empty.txt touch full.txt else rm -f full.txt touch empty.txt fi I like shell scripting a lot, but one disadvantage of it is that the shell cannot help you when you misspell, whereas a compiler like your C++ compiler can help you. Notice incidentally that I