EXAMPLES:
undef $foo;
my $bar = undef;
SEE ALSO:
perldoc -f undef
Questions tagged [undef]
57 questions
1
vote
4 answers
c# Quick way to undef all parameters
I have a C# winform app which is doing a lot of calculation. there is a "run" button to trigger the process. I would like to be able to "re-trigger or re-run or re-submit" the information without having to restart the program. Problem is I have a…
John Ryann
- 2,283
- 11
- 43
- 60
1
vote
1 answer
How do I remove this UndefVar error in my code?
I'm using this notebook provided by the Computational Thinking course and am running into an error when I execute this code.
import Pkg
Pkg.add(["Images", "ImageIO", "ImageMagick"])
using Images
philip_file =…
whyharsha
- 87
- 6
1
vote
2 answers
How do I make the STDIN in the Array stop? (PERL)
My @array will not stop taking in STDIN...
my @array = undef;
while (@array = undef){
@array = ;
for (@array[x]=5){
@array = defined;
}
}
Soup
- 45
- 5
1
vote
1 answer
Seeming evaluation of preprocessor code inside a #if false block
I'm working in C# via MonoDevelop 4.0.1 (Current version for Unity),
and have hit a seeming language weirdness.
Here's my entire .cs file:
#if false
#define foo
#endif
class myClass {
int member;
}
#if false
#error this error does not…
orion elenzil
- 4,484
- 3
- 37
- 49
1
vote
2 answers
Is it really necessary to explicitly define "undefine" even when the define is commented out?
I was having some problems with this code executing:
#if TRACE
dbgLog = new LogInfo( "PlatypusCE" );
#endif
This was occurring even though "TRACE" was commented out above, right after a large block of general comments:
//#define…
B. Clay Shannon-B. Crow Raven
- 8,547
- 144
- 472
- 862
1
vote
1 answer
undef value and printing it
This is my first time using Perl.
In Perl threads, the return value of the threads->exit() subroutine is undef value if the context is scalar.
#!/usr/bin/perl
use threads;
$t=threads->create({"context"=>"scalar"},
sub {…
Mahmoud Emam
- 1,499
- 4
- 20
- 37
1
vote
3 answers
How can I gracefully iterate over a key - value hash generated from JSON containing values set to 'undef' and 'null'?
I am pulling a third party's json response and sometimes the values of the fields are literally 'undef' or 'null'. If I try to do a print of the key and value of each object in this json, whenever there is a undef value it will throw an…
user2407720
0
votes
1 answer
Loop through headers in C preprocessor
Is there a way to loop through all the included/defined header files and then #undef them all?
If looping is the issue, is there another way to #undef all of them with ease?
tekknolagi
- 10,663
- 24
- 75
- 119
0
votes
2 answers
How to overwrite a macro definition using compiler options
I want to redefine a macro, without modifying the header or source files.
For example:
#define macro_1 Present -- Is what actually defined in the header file
For one set of execution I need this macro to be same as it is , but for another set of…
krupa n
- 1
- 2
0
votes
1 answer
weird behavior of #undef
#include
#define MY_CONST 10
#define MY_OTHER_CONST MY_CONST
#undef MY_CONST
int main() {
enum my_enum : int {
MY_CONST = 100
};
std::cout << MY_OTHER_CONST;
return 0;
}
I would expect 10 as an output, but this…
user3600124
- 829
- 1
- 7
- 19
0
votes
1 answer
Why is #undef not working for my function?
I defined something at the beginning:
#define noprint
Then I returned in my functions if it's defined:
void print()
{
#ifdef noprint
return;
#else
//do stuff
#endif
}
Then in the main function:
main()
{
#undef…
user15114051
0
votes
1 answer
Can #undef affect member functions in C++?
I have an Unreal Engine 4 project with several plugins. On of these plugins contains a FileHelper class with a method CreateFile. This has worked fine for months, but in a recent commit, a different plugin added a call to FileHelper::CreateFile and…
Tare
- 482
- 1
- 9
- 25
0
votes
2 answers
perl out of memory message processing just 64 XML file each of 2MB - unix
I tried globalising variables and undef , increasing data segment space in unix , localising variable , but still getting the same error. I need to process around 750 files .Can anyone help? Thanks. I know reading the entire file into string may be…
Dexters
- 2,419
- 6
- 37
- 57
0
votes
2 answers
How to check for an undef value in a Matrix (in Julia) and assign a new value?
I want to create a matrix A of undefined values and have the following code that works just fine.
A = Matrix{Tuple{Float64, Array{Int64, 1}}}(undef, 100, 100)
Later, I want to check if a particular cell is undefined and if so, assign a value after…
whyharsha
- 87
- 6
0
votes
1 answer
How should an undef error be interpreted in Erlang?
I am trying to make sense of the following error:
4> c(sv).
{ok,sv}
5> B=sv:start().
<0.93.0>
6> =ERROR REPORT==== 14-Jul-2020::21:44:13.256000 ===
Error in process <0.93.0> with exit value:
{undef,[{common,createProcess,
…
Bercovici Adrian
- 8,794
- 17
- 73
- 152