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What does “while True” mean in Python?
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while True means loop forever. The while statement takes an expression and executes the loop body while the expression evaluates to (boolean) "true". True always evaluates to boolean "true" and thus executes the loop body indefinitely. It's an idiom that you'll just get used to eventually! Most ...
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 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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How to read a line from the console in C?
... line in a C console program
The text entered might have a variable length and we can't make any assumption about its content.
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How to get .app file of a xcode application
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Build a release version, and the .app file is under build/Release folder of your project. Just copy it to Applications folder of your friend's machine. I don't think you need to build a installer.
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How do I encode and decode a base64 string?
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Null checks for input strings in both functions and the solution is perfect :)
– Sverrir Sigmundarson
Mar 29 '14 at 23:05
24
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How to check if a variable is an integer in JavaScript?
How do I check if a variable is an integer in JavaScript, and throw an alert if it isn't? I tried this, but it doesn't work:
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Java Replacing multiple different substring in a string at once (or in the most efficient way)
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Future reader : for regex, "(" and ")" will enclose the group to search. The "%" counts as a literal in the text. If your terms don't start AND end with the "%" they will not be found. So adjust prefixes and suffixes on both parts (text + code).
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problem with and :after with CSS in WebKit
...n a select box with the pseudo :after (to style my select box with 2 parts and without images). Here's the HTML:
9 Answers
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Can't find the 'libpq-fe.h header when trying to install pg gem
...nx), 11.10 (Oneiric Ocelot), 12.04 (Precise Pangolin), 14.04 (Trusty Tahr) and 18.04 (Bionic Beaver)):
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/usr/include/postgresql/libpq-fe.h
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So try installing libpq-dev or its equivalent for your OS:
For Ubuntu/Debian systems: sudo apt-get install libpq-dev
On Red Hat Linux (RHEL) systems:...