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(Built-in) way in JavaScript to check if a string is a valid number
...ter-intuitive. +num converts empty strings or strings with spaces to zero, and isNaN() assumes the same:
+'' // 0
+' ' // 0
isNaN('') // false
isNaN(' ') // false
But parseInt() does not agree:
parseInt('') // NaN
parseInt(' ') // NaN
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Attempt to present UIViewController on UIViewController whose view is not in the window hierarchy
Just started using Xcode 4.5 and I got this error in the console:
33 Answers
33
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How can I echo a newline in a batch file?
... The period thing in "echo." never stops amazing me. It's so dated, and still I always forget that the dot must be strictly concatenated with the command name, with no spaces between. There's no error in the post of yours, I'm writing this just as a reminder: "echo ." != "echo." !
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Python error “ImportError: No module named”
...ssing __init__.py (now called __init__.py.bin) means python doesn't understand toolkit as a package.
You create __init__.py in the appropriate directory and everything works... ?
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Validate phone number with JavaScript
I found this code in some website, and it works perfectly. It validates that the phone number is in one of these formats:
(123) 456-7890 or 123-456-7890
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How do I determine if a port is open on a Windows server? [closed]
...e default option 'telnet' is not recognized as an internal or external command, operable program or batch file. To solve this, just enable it: Click *Start** → Control Panel → Programs → Turn Windows Features on or off. In the list, scroll down and select Telnet Client and click OK.
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Windows recursive grep command-line
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findstr can do recursive searches (/S) and supports some variant of regex syntax (/R).
C:\>findstr /?
Searches for strings in files.
FINDSTR [/B] [/E] [/L] [/R] [/S] [/I] [/X] [/V] [/N] [/M] [/O] [/P] [/F:file]
[/C:string] [/G:file] [/D:dir list] [/A...
How to test an SQL Update statement before running it?
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In addition to using a transaction as Imad has said (which should be mandatory anyway) you can also do a sanity check which rows are affected by running a select using the same WHERE clause as the UPDATE.
So if you UPDATE is
UPDATE foo
SET bar = 42
WHERE col1 = 1
AND col2 = 'foobar';
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How does the “final” keyword in Java work? (I can still modify an object.)
...antics of final. In other words: final is only about the reference itself, and not about the contents of the referenced object.
Java has no concept of object immutability; this is achieved by carefully designing the object, and is a far-from-trivial endeavor.
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Growing Amazon EBS Volume sizes [closed]
I'm quite impressed with Amazon's EC2 and EBS services. I wanted to know if it is possible to grow an EBS Volume.
11 Answer...