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How to check for an undefined or null variable in JavaScript?
...xistingObj.someUndefProperty. An undefined property doesn't yield an error and simply returns undefined, which, when converted to a boolean, evaluates to false. So, if you don't care about
0 and false, using if(obj.undefProp) is ok. There's a common idiom based on this fact:
value = obj.prop || de...
Are PDO prepared statements sufficient to prevent SQL injection?
...erver's expecting on the connection both to encode ' as in ASCII i.e. 0x27 and to have some character whose final byte is an ASCII \ i.e. 0x5c. As it turns out, there are 5 such encodings supported in MySQL 5.6 by default: big5, cp932, gb2312, gbk and sjis. We'll select gbk here.
Now, it's very i...
Android destroying activities, killing processes
Hi I'm wondering how Android is managing memory and I can't find precise answer anywhere.
Let's assume I have an application with 5 activities on current activity stack (4 are stopped and 1 is resumed), there is no service connected. I press HOME button so that all of my activities are stopped.
I st...
What is the difference between LR, SLR, and LALR parsers?
What is the actual difference between LR, SLR, and LALR parsers? I know that SLR and LALR are types of LR parsers, but what is the actual difference as far as their parsing tables are concerned?
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What's the difference between a POST and a PUT HTTP REQUEST?
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HTTP PUT:
PUT puts a file or resource at a specific URI, and exactly at that URI. If there's already a file or resource at that URI, PUT replaces that file or resource. If there is no file or resource there, PUT creates one. PUT is idempotent, but paradoxically PUT responses are n...
Why is the gets function so dangerous that it should not be used?
...hat.)
It remained an official part of the language up to the 1999 ISO C standard, but
it was officially removed by the 2011 standard. Most C implementations still support it, but at least gcc issues a warning for any code that uses it.
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How do you get the logical xor of two variables in Python?
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Although this is clever and short, I'm not convinced it's clean. When someone reads this construct in the code, is it immediately obvious to them that this is an xor operation? I felt obliged to add a comment - a sign for me that I'm writing unclear...
What is the difference between 'protected' and 'protected internal'?
Can someone please elaborate me the difference between 'protected' and 'protected internal' modifiers in C#?
It looks they behave in same manner.
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What is the difference between ELF files and bin files?
The final images produced by compliers contain both bin file and extended loader format ELf file ,what is the difference between the two , especially the utility of ELF file.
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Which is faster : if (bool) or if(int)?
The above topic made me do some experiments with bool and int in if condition. So just out of curiosity I wrote this program:
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