I have two possible questions; can you use a ternary operator to initialize objects with overloaded constructors like
class thing { int x; int y;
[Code].....
I can get around it if I need to but I'd like to learn more about the ternary operator if I can, since I couldn't find anything online that addressed this particular issue, at least in a way I could detect.
I'm doing a refresher for C++ and have gotten to operator overloading. I'm trying to perform an operator overload with the insertion (<<) operator, but I have encountered a problem.
Here's my class [In a header file "Shinigami.h"]
#include<string> namespace K{ class Quincy; class Shinigami{ friend std::ostream& operator<<(std::ostream&, const Shinigami&);
[Code] .....
If the operator function is a friend of the 'Shinigami' class, why doesn't it recognize any of it's private members? I need it to be in this file because I'm doing a bit of association with the 'Quincy' class.
I thought it was the namespace, but I included that.
but how do you use an array as the condition, how will the code look?For example i want to write
Code:
string numbers[5] = {"one","two","three","four","five"}; numbers == "one" ? thumb : again; thumb and again will replace something else. Don't worry about them.
how do i say that if the numbers array is representing "one" then it replaces as "thumb", otherwise "again".
Is it usual to rely completly on the new operator in constructors/copy constructors. What if new trows an exception? The application ends and that's it? The new operator can be placed where it can't be catch like in constructor initialization list. What kind of practice I should adopt when using "new" in those cases?
The sample code below is taken from here... [URL] ....
class MemoryBlock { public:
// Simple constructor that initializes the resource. explicit MemoryBlock(size_t length) : _length(length) , _data(new int[length])
In that situation, << does not call the overloaded function, but rather calls the << method defined in the i/o library, which prints a message to the controlling terminal. So once it prints the message to the terminal, it then returns the out instance. Why return the out instance rather than a boolean like true? As you can see from the example, once the message is printed to terminal, out is not used anymore.
In stl map, if I insert two keys, say a and b. It looks like compare operator is called twice. First time a<b is called and second time b<a is called. Why are both a<b and b<a called?
Code: #include <iostream>#include <iomanip> using namespace std; class Score { private: // Value at which we'll shift digits from million_counter to billion_counter static const int THRESHOLD = 1000000000;
[Code] ....
It gives the errors: line 105 error: million_counter was not declared in this scope line 106 error: normalizeScore was not declared in this scope line 110 error: million_counter was not declared in this scope and more of that until line 170 error: no match for 'operator<<' in 'std:perator<< <std::char_traits<char> >((* & std::cout), ((const char*)"a+b is ")) <<operator+((*c(const Score*) (& a)), (*(const Score*)(& b)))'
I thought that because i declared friend functions, they would be able to access the private variables of the class.
I have done alot of googling for the scope resolution operator and Ive gained a bit of an understanding as to what it does i know it can distinguish between global and local variables, but I see it used to access methods/members of classes such as this example, why not just use a dot instead to access it?:
sql:: Driver *driver;
Why is the scope resolution operator being used here?
I liked that the above code does not put the result into a variable and then test the variable which would use more memory, and more lines of code. Is this thinking bad?
Well... I observed, as a non-professional programmer that "overloading operators" has some strict rules and some conventions... so any operator can differ from another. In order to have a clearest idea, I'd like to ask you to specify, for every operator, the correct (or best) way to overload it.
There are cases where you define &operator and cases where you define operator (without "&"). There are cases where operator are defined as "friend" inside class, and other cases where operator is declared externally.
example: ostream &operator<< (why it uses & ??)
So can we have a summary for all kind of operators?
I keep getting an undesired value in this code. I've tried several methods, but none are giving me the correct answer. The out put is always zero, when in this case it should be 10!!
Here's the object structure:
template<class T, class _b> struct quantity { private: T value; public: explicit quantity(T val): value(val) {}; T getValue() { return value; };
Why does it seem that the assignment operator is the harder operator to overload? Maybe it's just my luck, but I seem to always run into issues whenever I work with it. I hardly ever experience errors when overloading any of the other operators.
I'm trying to overload operator<<, but I get an error saying 'ostream' does not name a type. Am I forgetting to declare something else? ostream& operator<< (ostream& out, Struct &b);I made sure to #include <iostream> too.
I'm writing a program in C that performs operations on an array of 4-byte unsigned integers. Here's some usage examples:
+ n m // print sum of elements at indexes n and m & n m // bitwise and of elements... < n m // shift element at index n by m bits
I will have to implement functions for sum, bitwise-and, bitwise-or, xor, left-shift, right-shift... All with the same function format:
void print_operation(unsigned n, unsigned m) { printf("%u ", n some_operator m); }
Is there any way that I can pass an operator as an argument so that I can have a single elegant function that looks like this? I'd really like this to work like callback functions.
void print_operation(unsigned n, unsigned m, some_type oper) { printf("%u ", oper(n, m)); }
I am having a bit of an issue figuring out how to operator overload with chaining. I have this as my operator= function (Its for linked lists)
WORD & WORD::operator=(const WORD & Org){ cout << " operator= has been called WITH CHAINING "; character *p = front;
[Code] ....
I want to be able to do X = X = X where X is of class WORD, but it errors when that line is called. And by error, I dont mean a written error, it just compiles, then says 'MSVC has stopped working' on a new pop up.
I want to overload ostream& operator << so that it prints content of whatever container I want. I wrote something like this:
Code: #include <iostream> #include <list> #include <set> template <class T> ostream& operator << (ostream& strm, T l) { for (class T::iterator it = l.begin(); it != l.end();++it)
[Code] ...
It works. However, it'd be nice to actually have these spaces between numbers. There's the problem: when I uncomment the code (and remove ++it from the for loop), the compilers gives me a bunch of messages with the "main" reading:
Code: stl_test.cpp: In function "std::ostream& operator<<(std::ostream&, T)": stl_test.cpp:19: error: ambiguous overload for "operator<<" in "strm << " " "
Why does it not work? (it seems like << isn't overloaded for const char *, but simple cout << " "; works, so...)