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Polymorphism in C++
...ecific code selected?
Run time means the compiler must generate code for all the types the program might handle while running, and at run-time the correct code is selected (virtual dispatch)
Compile time means the choice of type-specific code is made during compilation. A consequence of this: say...
Counting inversions in an array
...m to do the following: Given array A[1... n] , for every i < j , find all inversion pairs such that A[i] > A[j] . I'm using merge sort and copying array A to array B and then comparing the two arrays, but I'm having a difficult time seeing how I can use this to find the number of inversions...
How to change collation of database, table, column?
...
You need to either convert each table individually:
ALTER TABLE mytable CONVERT TO CHARACTER SET utf8mb4
(this will convert the columns just as well), or export the database with latin1 and import it back with utf8mb4.
...
How can I force division to be floating point? Division keeps rounding down to 0?
... a floating point number in Python in the following?
c = a / b
What is really being asked here is:
"How do I force true division such that a / b will return a fraction?"
Upgrade to Python 3
In Python 3, to get true division, you simply do a / b.
>>> 1/2
0.5
Floor division, the classic di...
How to delete all Annotations on a MKMapView
Is there a simple way to delete all the annotations on a map without iterating through all the displayed annotations in Objective-c?
...
How do I show the value of a #define at compile-time?
...ring. When there is more than one component to the argument then they must all be strings so that string concatenation can be applied. The preprocessor can never assume that an unquoted string should be treated as if it were quoted. If it did then:
#define ABC 123
int n = ABC;
would not compile.
...
Is there a “goto” statement in bash?
...atement in bash ? I know It is considered bad practice, but I need specifically "goto".
12 Answers
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Reference — What does this symbol mean in PHP?
... have the same results.
Pre-increment is a little bit faster because it really increments the variable and after that 'returns' the result. Post-increment creates a special variable, copies there the value of the first variable and only after the first variable is used, replaces its value with seco...
How to implement an abstract class in ruby?
I know there is no concept of abstract class in ruby. But if at all it needs to be implemented, how to go about it? I tried something like...
...
PHP mkdir: Permission denied problem
...te permissions on the directory.
Here's what you do in Ubuntu
Make sure all files are owned by the Apache group and user. In Ubuntu it is the www-data group and user
chown -R www-data:www-data /path/to/webserver/www
Next enabled all members of the www-data group to read and write files
chmod -R...