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How to overload the operator++ in two different ways for postfix a++ and prefix ++a?
...plement postfix in terms of prefix.
//
Number operator++ (int) // postfix ++
{
Number result(*this); // make a copy for result
++(*this); // Now use the prefix version to do the work
return result; // return the copy ...
Confused about __str__ on list in Python [duplicate]
...
Python has two different ways to convert an object to a string: str() and repr(). Printing an object uses str(); printing a list containing an object uses str() for the list itself, but the implementation of list.__str__() calls repr() for the individual it...
How to use a variable to specify column name in ggplot
...t will remain around for a long time).
The idiomatic way now would be to convert to a symbol the string that the variable contains, using sym()(which is almost the same as base aliases as.name() / as.symbol()), and unquote it using !!
Simulating OP's data we can do :
library(tidyverse)
rates.by....
What is the use of static variable in C#? When to use it? Why can't I declare the static variable in
...
Example without declaring it static:
public class Variable
{
public int i = 5;
public void test()
{
i = i + 5;
Console.WriteLine(i);
}
}
public class Exercise
{
static void Main()
{
Variable var = new Variable();
var.test();
Variab...
Linq list of lists to single list
...
Here is a sample code for you:
List<int> listA = new List<int> { 1, 2, 3, 4, 5, 6 };
List<int> listB = new List<int> { 11, 12, 13, 14, 15, 16 };
List<List<int>> listOfLists = new List<List<int>> { listA, listB };
...
How to elegantly check if a number is within a range?
...
There are a lot of options:
int x = 30;
if (Enumerable.Range(1,100).Contains(x))
//true
if (x >= 1 && x <= 100)
//true
Also, check out this SO post for regex options.
...
Java String - See if a string contains only numbers and not letters
...ontains only numerics.
If you actually want to use the numeric value, use Integer.parseInt() or Double.parseDouble() as others have explained below.
As a side note, it's generally considered bad practice to compare boolean values to true or false. Just use if (condition) or if (!condition).
...
Why NSUserDefaults failed to save NSMutableDictionary in iOS?
...
When I need the data, I read out the NSData, and use NSKeyedUnarchiver to convert NSData back to the object.
It is a little cumbersome, because i need to convert to/from NSData everytime, but it just works.
Here is one example per request:
Save:
NSUserDefaults *defaults = [NSUserDefaults stand...
How does a garbage collector avoid an infinite loop here?
...ion running. The main thread completes effectively right away, at which point the finalizer thread simply runs as many times as it gets a chance to before the process gets torn down. Nothing is keeping the program alive.
s...
What is the C++ function to raise a number to a power?
...e <cmath> header has these overloads:
pow(float, float);
pow(float, int);
pow(double, double); // taken over from C
pow(double, int);
pow(long double, long double);
pow(long double, int);
Now you can't just do
pow(2, N)
with N being an int, because it doesn't know which of float, double...