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MongoDB SELECT COUNT GROUP BY
...
I need some extra operation based on the result of aggregate function. Finally I've found some solution for aggregate function and the operation based on the result in MongoDB. I've a collection Request with field request, source, status...
Why are preprocessor macros evil and what are the alternatives?
...can't be debugged.
When you have a macro that translates to a number or a string, the source code will have the macro name, and many debuggers, you can't "see" what the macro translates to. So you don't actually know what is going on.
Replacement: Use enum or const T
For "function-like" macros,...
How do I reverse a C++ vector?
...am>
template<class InIt>
void print_range(InIt first, InIt last, char const* delim = "\n"){
--last;
for(; first != last; ++first){
std::cout << *first << delim;
}
std::cout << *first;
}
int main(){
int a[] = { 1, 2, 3, 4, 5 };
std::vector<int> v(a, ...
Markdown `native` text alignment
...
For Markdown Extra you can use custom attributes:
# Example text {style=text-align:center}
Vim: How to insert in visual block mode?
...ress ctrl+v, press j a few times, and I see the cursor highlight the first character of a few lines. I press shift+i. The cursor is moved to the first character of the first line, but I'm back to normal mode. I know this because if I press "a", it moves the character to the right, and it says "-- IN...
Shell script “for” loop syntax
...ort those features in the POSIX standard, but by default let some of their extra features through. The C-style for-loop is not a POSIX feature, but may be in sh mode by the actual shell.
– chepner
Sep 12 '13 at 19:41
...
What is two way binding?
... emberjs, to create two way binding is by creating a new property with the string Binding at the end, then specifying a path from the global scope:
App.wife = Ember.Object.create({
householdIncome: 80000
});
App.husband = Ember.Object.create({
householdIncomeBinding: 'App.wife.householdIncome'...
Difference between array_map, array_walk and array_filter
...onal array. Every element's value changes in place into a more informative string specifying its key, category and value.
<?php
$f = function(&$item,$key,$prefix) {
$item = "$key: $prefix: $item";
};
array_walk($nu, $f,"fruit");
var_dump($nu);
?>
See demo
Note: the callba...
How to write log base(2) in c/c++
...uld work assuming integer is 32 bit wide, no ? For 64 bit it would have an extra i>>32 . But since Java has only 32-bit ints, it is fine. For C/C++ it needs to be considered.
– Zoso
May 27 '17 at 8:12
...
Why would iterating over a List be faster than indexing through it?
...effectively O(N^2) just to traverse the list!
If instead I did this:
for(String s: list) {
System.out.println(s);
}
then what happens is this:
head -> print head -> item1 -> print item1 -> item2 -> print item2 etc.
all in a single traversal, which is O(N).
Now, going to th...