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What is the difference between == and Equals() for primitives in C#?
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Short answer:
Equality is complicated.
Detailed answer:
Primitives types override the base object.Equals(object) and return true if the boxed object is of the same type and value. (Note that it will also work for nullable types; non-null nullab...
Detecting an undefined object property
...ty, and will therefore return undefined by default when you try and access it:
if(!o.hasOwnProperty('myProperty')) {
alert("myProperty does not exist");
}
To check if the value associated with an identifier is the special value undefined, or if that identifier has not been declared. Note: this ...
Does assignment with a comma work?
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There's a lot going on here, but basically, it comes down to the comma operator.
The comma operator evaluates both of its operands (from left to right) and returns the value of the second operand.
This code:
aaa = 1,2,3
Is equivalent to:
aaa = 1;
2;
3;
So...
Why does flowing off the end of a non-void function without returning a value not produce a compiler
...e rationale includes that checking if every code path returns a value is quite difficult, and a return value could be set with embedded assembler or other tricky methods.
From C++11 draft:
§ 6.6.3/2
Flowing off the end of a function [...] results in undefined behavior in a value-returning fun...
notifyDataSetChanged example
...Application the notifyDataSetChanged() method for an ArrayAdapter but it doesn't work for me.
5 Answers
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What does $.when.apply($, someArray) do?
...and Promises and keep coming across $.when.apply($, someArray) . I'm a little unclear on what this does exactly, looking for an explanation that one line works exactly (not the entire code snippet). Here's some context:
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When do you use Java's @Override annotation and why?
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Use it every time you override a method for two benefits. Do it so that you can take advantage of the compiler checking to make sure you actually are overriding a method when you think you are. This way, if you make a common mi...
What is the difference between a function expression vs declaration in JavaScript? [duplicate]
...hes that line of code.
So if you try to call a function expression before it's loaded, you'll get an error! If you call a function declaration instead, it'll always work, because no code can be called until all declarations are loaded.
Example: Function Expression
alert(foo()); // ERROR! foo was...
versionCode vs versionName in Android Manifest
I had my app in the android market with version code = 2 and version name = 1.1
10 Answers
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Check if object exists in JavaScript
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You can safely use the typeof operator on undefined variables.
If it has been assigned any value, including null, typeof will return something other than undefined. typeof always returns a string.
Therefore
if (typeof maybeObject != "undefined") {
alert("GOT THERE");
}
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