operators

Why aren't "and" and "or" operators in Python?

I wasn't aware of this, but apparently the and and or keywords aren't operators. They don't appear in the list of python operators. Just out of sheer curiosity, why is this? And if they aren't operators, what exactly are they? ...

isn't there an operator in c to change the sign of a int float etc from negative to positive or vice versa?

trying to find absolute value and i thought there was a simple way to just invert the sign with '~' or something. ...

a = b = 5 in VB.NET - impossible?

Is it possible in VB.NET doing a = b = 5? (I know that = is a comparison operator too) I mean do not result (if b = 2 by e.g.) a = false b = 2 HOW to do it, however, in situations like bellow? The inconvenient caused this question in my code: some objects a, b, .. z are passed by ref in a method, if I don't initialize them compile...

+ and += operators are different?

>>> c = [1, 2, 3] >>> print(c, id(c)) [1, 2, 3] 43955984 >>> c += c >>> print(c, id(c)) [1, 2, 3, 1, 2, 3] 43955984 >>> del c >>> c = [1, 2, 3] >>> print(c, id(c)) [1, 2, 3] 44023976 >>> c = c + c >>> print(c, id(c)) [1, 2, 3, 1, 2, 3] 26564048 What's the difference? are += and + not supposed to be merely syntactic sugar? ...

What does this statement mean?

While $w is an Array ( [0] => 4, [1] => 6 ) what does this statement mean: $day == $w[0] || $day == $w[1] || $day < ((7 + $w[1] - $w[0]) % 7); Please help. I have not seen the || operator inside other than an if or while statement. Thank you. EDIT 01: This is the original function where it is used to find the number of a particul...

Logic differences in C and Java

Compile and run this code in C #include <stdio.h> int main() { int a[] = {10, 20, 30, 40, 50}; int index = 2; int i; a[index++] = index = index + 2; for(i = 0; i <= 4; i++) printf("%d\n", a[i]); } Output : 10 20 4 40 50 Now for the same logic in Java class Check { public static void main(String[] ar) { int ...

explicit copy constructor or implicit parameter by value

I recently read (and unfortunately forgot where), that the best way to write operator= is like this: foo &operator=(foo other) { swap(*this, other); return *this; } instead of this: foo &operator=(const foo &other) { foo copy(other); swap(*this, copy); return *this; } The idea is that if operator= is called with...

How does conversion operator return a value?

I am a newbie to c++ and please don't get mad at me for asking something very basic. Here's my quesion: For a class A, an integer conversion operator would look something like operator int() //Here we don't specify any return type { return intValue; } How does the above function is able to return something when its signature say...

Javascript question

(myVar && foo()) what does the above code mean? what is it equivalent to? this is an inline code i think it runs on a single line ...

how does less than (<) operator work with mixed types in c

Can someone explain how does less than op work in C? In particular how it works when types of left hand side and right hand side operands are different? Does it compare them based on type of the first one or the second one? ...

C++ Trouble with operator code inheritage: am I require to copy same code for all derived classes?

I'd like to write a group of class D_I (aka I=1,2,... just I mean '_I' to be class proper name, not integer) which handle some (boolean, for example) operations F with same meaning for all classes. But also I want to operate with "sums" of object of such classes, different classes of the group might be "added" together. Mentioned operati...

The 3 different equals

Can someone explain to me the difference between =, ==, and ===? I think using one equal sign is to declare a variable while two equal signs is for a comparison condition and lastly three equal signs is for comparing values of declared variables. ...

"or" operator without repeating the left hand condition again.

Ever since I started programming properly using good old VB6 and up until present day, I often still get burned (and just have) by this in programming: if x == something or x == somethingelse I often end up writing: if x == something or somethingelse Just out of pure interest, does any langauge/languages out there support this? ...

pass < or > operator into function as parameter?

Inside my function there is an if() statement like this: if(passedValue < staticValue) But I need to be able to pass a parameter dictating whether the if expression is like above or is: if(passedValue > staticValue) But I cant really pass < or > operator in has a parameter, so I was wondering what is the best way to do this? Also ...

How does the Groovy in operator work?

The Groovy "in" operator seems to mean different things in different cases. Sometimes x in y means y.contains(x) and sometimes it seems to call y.isCase(x). How does Groovy know which one to call? Is there a particular class or set of classes that Groovy knows about which use the .contains method? Or is the behavior triggered by the ...

C++: Overloading operator=

Okay so I have a class that has 'weak typing' I.E. it can store many different types defined as: #include <string> class myObject{ public: bool isString; std::string strVal; bool isNumber; double numVal; bool isBoolean; bool boolVal; double operator= (const myObject &); }; I would like ...

Objective-C Condtions operators weirdness

Okay here's the damned thing: - (void)setMinimumNumberOfSides:(NSNumber *)newMinimumNumberOfSides { if (newMinimumNumberOfSides != minimumNumberOfSides) { NSNumber *minimum = [[NSNumber alloc] initWithInt:(int)2]; if (newMinimumNumberOfSides > minimum) { [newMinimumNumberOfSides retain]; [mi...

What will this construction do?

std::vector<int> a; int p; int N; // ... p = a[ N>>1 ]; What is the N>>1 part? ...

Ruby: difference between || and 'or'

It is really hard to google this, because neither || nor 'or' are good words to search for :) I am wondering if there is a difference between the two, or if it is just a matter of preference? ...

Using operator+ without leaking memory?

So the code in question is this: const String String::operator+ (const String& rhs) { String tmp; tmp.Set(this->mString); tmp.Append(rhs.mString); return tmp; } This of course places the String on the stack and it gets removed and returns garbage. And placing it on the heap would leak memory. So how shoul...