pass-by-reference

问题 I'm looking for a way to use a function as an argument to another function in GLSL. In regular C, it can be simulated by passing a function pointer as a function argument. It also seems that other languages (like HLSL) now provide ways to deal with high-level constructs like higher-order functions, or can simulate them with clever use of HLSL structures. unfortunately I'm stuck with GLSL for now, and I can't find any way to simulate higher-order functions. Is it really impossible in current

问题 How can I pass a map by reference into a function? Visual Studio 2010 is giving me an unresolved externals error. Currently, I have the following simplified code: void function1(){ map<int, int> * my_map = new map<int, int>(); function2(*my_map); } void function2(map<int, int> &temp_map){ //do stuff with the map } There's a few answers to similar questions here, but they make use of typedef and adding std:: to the beginning of the definition but I'm really not sure why. int ComputerPlayer:

问题 How can I pass a map by reference into a function? Visual Studio 2010 is giving me an unresolved externals error. Currently, I have the following simplified code: void function1(){ map<int, int> * my_map = new map<int, int>(); function2(*my_map); } void function2(map<int, int> &temp_map){ //do stuff with the map } There's a few answers to similar questions here, but they make use of typedef and adding std:: to the beginning of the definition but I'm really not sure why. int ComputerPlayer:

问题 short int PC = 0; int main() { foo(&PC) ; } void foo(short int PC) { PC++; } How do I successfully update the global variable of PC? Note : PC must be passed as a parameter and the global variable needs to be modified via the parameter. As you can tell I am new to C and am trying to understand the difference between * and & . Any help would be much appreciated. 回答1: You just need to take the argument as a pointer: short int PC = 0; void foo(short int *pc) { (*pc)++; } int main() { foo(&PC) ;

问题 I know that pointers hold the address of a variable. And references point to the same address in the symbol table (that is, the same address of the variable, that they are assigned to). My question is, how do reference to pointers exactly work. And when do we need them, as opposed to using pointer alone (and not using reference to pointer). It will be helpful if you could explain me the use of reference to pointer, with respect to a singly linked list. I have the following code that deletes

问题 As seen here, structs are passed by copy and classes by reference. But why is passing a struct by reference using the ref keyword still slower than passing a reference to a class ? I got different speeds for my program by replacing the struct keywords with class . All of the variables were already passed with the ref keyword. By changing keywords, I got 20% speed increase in my tests. Shoudn't the speed remain the same since I was already passing by reference ? What am I not understanding ?

问题 Below is my code for assembly language. I can pass by a stack parameter value using "push [edi]" but I cannot seem to pass by reference using "push OFFSET [edi]". What's the correct syntax to pass something by reference in this case? sortList PROC ;Parameter memory addresses: ;numbers @ [ebp+8] ;list @ [ebp+12] ;Used to access stack parameters push ebp mov ebp, esp ;Sets up the array mov edi, [ebp+12] ;Puts in the address of the list array mov ecx, [ebp+8] ;Sets up the loop counter for the

问题 So for the past few days I have been tearing my hair out trying to get a class to clone properly. The problem is that cloning doesn't remove/redo any of the pass-by-reference. The result is, that the main data object is still passed as a reference, thus completely negating the effect of the clone. Here's a simplified version of the problem: class my_class { private $data; public $var1; public $var2; public $var3; public function __construct() { $this->data = new stdClass; $this->data->var1 =

问题 Code: #include <functional> struct Foo { virtual void mf() = 0; }; struct Bar: Foo { virtual void mf() {} }; int main() { Bar o; std::reference_wrapper<Foo const> wrapper( o ); } Result with MinGW g++ 4.6.1: [d:\dev\test] > g++ foo.cpp -std=c++0x [d:\dev\test] > _ Result with Visual C++ 10.0: [d:\dev\test] > cl foo.cpp foo.cpp C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\xxcallwrap(8) : error C2259: 'Foo' : cannot instantiate abstract class due to following members: 'void

问题 I got the answer NO! Because passing by value and passing by reference looks identical to the caller. However, the code below compiles right class A { public: void f(int i) {} void f(int& i) {} }; But when I try to use it, there is compile error. int main () { A a; int i = 9; int& j = i; a.f(1); a.f(i); a.f(j); return 0; } Why does not the compiler disable it even without knowing it is going to be used? 回答1: Yes, they can be overloaded based on reference or not. That is why it's perfectly