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Null vs. False vs. 0 in PHP
...ill get inequality.
So why are they useful ?
Well, look at the strrpos() function. It returns False if it did not found anything, but 0 if it has found something at the beginning of the string !
<?php
// pitfall :
if (strrpos("Hello World", "Hello")) {
// never exectuted
}
// smart move ...
Insert, on duplicate update in PostgreSQL?
...RT, as appropriate:
CREATE TABLE db (a INT PRIMARY KEY, b TEXT);
CREATE FUNCTION merge_db(key INT, data TEXT) RETURNS VOID AS
$$
BEGIN
LOOP
-- first try to update the key
-- note that "a" must be unique
UPDATE db SET b = data WHERE a = key;
IF found THEN
...
Why do we need message brokers like RabbitMQ over a database like PostgreSQL?
...em) on top of a database. I can tell you that it is possible, but it's not fun and it doesn't usually pay off to do it. Some of the problems you mention can be worked around, but it does increase the complexity quite a lot. All in all I agree: use a dedicated MQ system, if you need one. For low work...
Why not infer template parameter from constructor?
... infer template parameters from class constructors, much as it can do from function parameters? For example, why couldn't the following code be valid:
...
Code Golf - π day
...
@Load: 5.1.2.2.1/1: The function called at program startup is named main. It shall be defined … or in some other implementation-defined manner. So that's because the implementation can accept this form.
– kennytm
...
Find XOR of all numbers in a given range
...s the fact that there is a pattern of results in the running XORs. The f() function calculates the XOR total run from [0, a]. Take a look at this table for 4-bit numbers:
0000 <- 0 [a]
0001 <- 1 [1]
0010 <- 3 [a+1]
0011 <- 0 [0]
0100 <- 4 [a]
0101 <- 1 [1]
0110 <- 7 [a+1...
Is there a better way to express nested namespaces in C++ within the header
...races that were missing comments about which brace closes which scope? Not fun.).
MY_COMPANY_BEGIN
MY_LIBRARY_BEGIN
class X { };
class Y { };
MY_LIBRARY_END
MY_COMPANY_END
If you want to put all namespace declarations on a single line you can do that as well with a bit of (pretty ugly) preproc...
Is the != check thread safe?
...
It has all been well explained by Stephen C. For fun, you could try to run the same code with the following JVM parameters:
-XX:InlineSmallCode=0
This should prevent the optimisation done by the JIT (it does on hotspot 7 server) and you will see true forever (I stopped a...
What's the difference between an exclusive lock and a shared lock?
...
I wrote this answer down because I thought this would be a fun (and fitting) analogy:
Think of a lockable object as a blackboard (lockable) in a class room containing a teacher (writer) and many students (readers).
While a teacher is writing something (exclusive lock) on the board:...
Image Processing: Algorithm Improvement for 'Coca-Cola Can' Recognition
...
Fun problem: when I glanced at your bottle image I thought it was a can too. But, as a human, what I did to tell the difference is that I then noticed it was also a bottle...
So, to tell cans and bottles apart, how about sim...