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Object reference not set to an instance of an object.Why doesn't .NET show which object is `null`?
...ull
IL_0002: stloc.0 // s
IL_0003: ldloc.0 // s
IL_0004: callvirt System.String.get_Length
IL_0009: call System.Console.WriteLine
It is the callvirt opcode that throws the NullReferenceException and it does that when the first argument on the evaluation stack is a null ...
Django REST framework: non-model serializer
...urn JSON and XML to the API consumer. You can also enable YAML by just installing the required python module. Django-rest-framework will output any basic object like dict, list and tuple without any extra work on your part.
So basically you only have to create the function or class that takes in ar...
Fastest sort of fixed length 6 int array
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Rex KerrRex Kerr
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IllegalStateException: Can not perform this action after onSaveInstanceState with ViewPager
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Please check my answer here. Basically I just had to :
@Override
protected void onSaveInstanceState(Bundle outState) {
//No call for super(). Bug on API Level > 11.
}
Don't make the call to super() on the saveInstanceState method. This was messing t...
Setting up two different static directories in node.js Express framework
...llip KovalevPhillip Kovalev
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Comma in C/C++ macro
...his is also a problem for square brackets and braces, even though those usually occur as balanced pairs.) You can enclose the macro argument in parentheses:
FOO((std::map<int, int>), map_var);
The problem is then that the parameter remains parenthesized inside the macro expansion, which pr...
How to get all subsets of a set? (powerset)
...owerset([4, 5, 6])))
Using yield means that you do not need to calculate all results in a single piece of memory. Precalculating the masks outside the main loop is assumed to be a worthwhile optimization.
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How to tell if JRE or JDK is installed
I have one computer that I intentionally installed JDK on. I have another computer with JRE, for, among other things, testing. However, when I got a java application working on this computer, and then tried it on another, it complained that JDK was required. How can I check if JDK was somehow instal...
SSMS插件开发指南 - C/C++ - 清泛网 - 专注C/C++及内核技术
...(C:\ProgramData\Application Data\Microsoft\MSEnvShared\Addins\)
Will install add-in for all users on the machine.
Putting SSMSAddin.addin into %APPDATA%\Microsoft\MSEnvShared\Addins\
(C:\Users\UserName\AppData\Roaming\Microsoft\MSEnvShared\Addins\)
will install for specific user only.
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Python: most idiomatic way to convert None to empty string?
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If you actually want your function to behave like the str() built-in, but return an empty string when the argument is None, do this:
def xstr(s):
if s is None:
return ''
return str(s)
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