Questions about items that can be described as empty or having no data value
Questions tagged [is-empty]
776 questions
3929
votes
54 answers
How do I check for an empty/undefined/null string in JavaScript?
Is there a string.Empty in JavaScript, or is it just a case of checking for ""?

casademora
- 67,775
- 17
- 69
- 78
470
votes
11 answers
What is the best way to test for an empty string in Go?
Which method is best (most idomatic) for testing non-empty strings (in Go)?
if len(mystring) > 0 { }
Or:
if mystring != "" { }
Or something else?

Richard
- 10,122
- 10
- 42
- 61
337
votes
10 answers
How to find whether or not a variable is empty in Bash
How can I check if a variable is empty in Bash?

Tree
- 9,532
- 24
- 64
- 83
319
votes
12 answers
How to check if a file is empty in Bash?
I have a file called diff.txt. I Want to check whether it is empty.
I wrote a bash script something like below, but I couldn't get it work.
if [ -s diff.txt ]
then
touch empty.txt
rm full.txt
else
touch full.txt
rm…

Mich
- 3,253
- 2
- 14
- 6
263
votes
18 answers
Detect if an input has text in it using CSS -- on a page I am visiting and do not control?
Is there a way to detect whether or not an input has text in it via CSS? I've tried using the :empty pseudo-class, and I've tried using [value=""], neither of which worked. I can't seem to find a single solution to this.
I imagine this must be…

JacobTheDev
- 17,318
- 25
- 95
- 158
164
votes
2 answers
ValueError when checking if variable is None or numpy.array
I'd like to check if variable is None or numpy.array. I've implemented check_a function to do this.
def check_a(a):
if not a:
print "please initialize a"
a = None
check_a(a)
a = np.array([1,2])
check_a(a)
But, this code raises…

Light Yagmi
- 5,085
- 12
- 43
- 64
163
votes
24 answers
Check string for nil & 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
}
}

netwire
- 7,108
- 12
- 52
- 86
122
votes
5 answers
Check if array is empty or null
I would like to know how to check if an array is empty or null in jQuery. I tried array.length === 0 but it didn't work. It did not throw any error either.
This is the code:
var album_text = new…

input
- 7,503
- 25
- 93
- 150
95
votes
13 answers
Checking if a collection is empty in Java: which is the best method?
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…

Vikrant
- 1,809
- 1
- 13
- 18
75
votes
8 answers
'IsNullOrWhitespace' in JavaScript?
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…

Scott
- 4,066
- 10
- 38
- 54
74
votes
7 answers
How to convert empty spaces into null values, using SQL Server?
I have a table and the columns on this table contains empty spaces for some records. Now I need to move the data to another table and replace the empty spaces with a NULL value.
I tried to use:
REPLACE(ltrim(rtrim(col1)),' ',NULL)
but it doesn't…

niceApp
- 2,913
- 8
- 35
- 36
64
votes
8 answers
How to fully dump / print variable to console in the Dart language?
Hey there I am searching for a function which is printing a dynamic variable as completely as possible to the console in Dart language.
In PHP for instance I would use var_dump() in order to get all information about a variable.
In JavaScript I…

Blackbam
- 17,496
- 26
- 97
- 150
62
votes
4 answers
Why use null function instead of == [] to check for empty list in Haskell?
I am reading through the "Starting Out" chapter of Learn You a Haskell for Great Good!. It says:
null checks if a list is empty. If it is, it returns True, otherwise it returns False. Use this function instead of xs == [] (if you have a list called…

徐保钰
- 793
- 1
- 7
- 17
58
votes
6 answers
Is it possible to set an object to null?
Further in my code, I check to see check if an object is null/empty.
Is there a way to set an object to null?

John
- 629
- 1
- 5
- 7
55
votes
4 answers
VBA Check if variable is empty
I have an object and within it I want to check if some properties are set to False, like:
If (Not objresult.EOF) Then
'Some code
End if
But sometimes, objresult.EOF is Empty; how can I check for this?
IsEmpty function is for excel cells…

fessguid
- 559
- 1
- 5
- 3