reference

问题 What is the difference between the following parameter passing mechanisms in C++? void foo(int &x) void foo(int *x) void foo(int **x) void foo(int *&x) I'd like to know in which case the parameter is being passed by value or passed by reference. 回答1: void foo(int &x) passes a reference to an integer. This is an input/output parameter and can be used like a regular integer in the function. Value gets passed back to the caller. void food(int *x) passes a pointer to an integer. This is an input

问题 The basic example: var b = 10; var c = b; b++; console.log(b,c); >> 11 10 c looks like a copy of b . But in another case: var x = {}; var y = x; x.abc = 10; console.log(x.abc, y.abc); >> 10 10 Why is the y not a copy of x , but a reference which points to the same instance x points to? Also, I guessed b++ creates another instance, so b points to the new instance but c points to the old one. However... var u = 10; setTimeout(function() { console.log(u); }, 10000) u++; >> 11 If u++ creates a

问题 I'm no Access expert, and I have an (I hope!) simple question... I have a form with a number of records. In some textboxes I just present values from the underlying table - so they are bound to the corresponding fields. But some textboxes should contain calculated values. Some calculations are complicated and involves many fields from the table. I write the calculation as a VBA function. I could enter something like this as "Control Source": =MyFunction([Field1], [Field2], [Field3] ...) But I

问题 This question already has answers here : Closed 9 years ago . Possible Duplicates: How to pass objects to functions in C++? is there any specific case where pass-by-value is preferred over pass-by-const-reference in C++? I have members of a class implemented like this: void aaa(int a, float b, short c) { bbb(a, b); } void bbb(int a, float b) {} If the values of a, b and c were stored in my class as constants, then would it have been better/sensible to use my functions as shown below or as

问题 I am trying to create a script that allows me to display a hyperlink that redirects the user to a random url selected out of four sites. So far I have created an array for the sites, and a function that attempts to generate the random url. For my purpose it is important for the output ("Click to go to a random site") is not a button, but a simple (clickable) string. When running the code I get a reference error "link is not defined (on line 18)". I thought that I had defined link in the code

问题 I am trying to create a script that allows me to display a hyperlink that redirects the user to a random url selected out of four sites. So far I have created an array for the sites, and a function that attempts to generate the random url. For my purpose it is important for the output ("Click to go to a random site") is not a button, but a simple (clickable) string. When running the code I get a reference error "link is not defined (on line 18)". I thought that I had defined link in the code

问题 There's some debate here over which is better for referencing our common code base from other projects: by project or by assembly. I'm in favor of referencing the project, especially since we have automated unit tests that prove that the common code does what it needs to. The thought from the other camp is to lock down those projects and only release assemblies once a month or something. Then force all projects to reference the assemblies. They think this will protect them from deploying

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: warning: returning reference to temporary I am getting the error "returning reference to temporary" on the second line below. class Object : public std::map <ExString, AnotherObject> const { public: const AnotherObject& Find (const ExString& string ) const { Object::const_iterator it = find (string); if (it == this->end()) { return AnotherObject() }; return ( it->second ); } } My class implements std::map. I am

问题 I have a CommonUtils lib I have built into a dll which I file reference from several of my projects. CommonUtils depends on log4net.dll which was set as a file reference and copy-local=true when CommonUtils.dll was built. log4net.dll and CommonUtils.dll are not in GAC. Everything works fine in MyWorkingProject where I only have a file reference to CommonUtils.dll - log4net.dll shows up in the output directory (as it is a dependency of CommonUtils.dll but not referenced from MyWorkingProject).

问题 I'm developing an iPhone app, and I'm kinda new to Objective-C and also the class.h and class.m structure. Now, I have two classes that both need to have a variable of the other one's type. But it just seems impossible. If in class1.m (or class2.m) I include class1.h, and then class2.h, I can't declare class2 variables in class1.h, if I include class2.h and then class1.h, I can't declare class1 variables in class2.h. Hope you got my idea, because this is driving me nuts. Is it really