new-operator

问题 Consider the code auto p = new T( U(std::move(v)) ); The initializer is then U(std::move(v)) . Let's assume that T( U(std::move(v)) ) does not throw. If the initializer is evaluated after the underlying memory allocation, the code is then strong-exception-safe. Otherwise, it is not. Had memory allocation thrown, v would have already been moved. I'm therefore interested in the relative order between memory allocation and initializer evaluation. Is it defined, unspecified, or what? 回答1: Yes,

问题 Im trying to understand why new runs against the function rather than the return of the function in the example y = : function returnFunction(){ return function blah(str){ this.x = str; return this;}} y = new returnFunction()("blah") // output: Window {x: "blah"; top: Window, window: Window, location: Location, ....} x = new (returnFunction())("blah") // output: blah {x: "blah"} z = new function blah(){return this;}() // output: blah {} zz = new function(){return this;}() //note the missing

问题 When I type -> rails new test_app, it only does the following -> create create README.md create Rakefile create .ruby-version create config.ru create .gitignore create Gemfile run git init from "." I was able to run this command successfully (where it created all the folders and files needed in a rails app) in my c:\users\ directory, however was not able to run it anymore after that. I have also deleted all rails related files in that directory and retried, but have had no success. Please

问题 When I type -> rails new test_app, it only does the following -> create create README.md create Rakefile create .ruby-version create config.ru create .gitignore create Gemfile run git init from "." I was able to run this command successfully (where it created all the folders and files needed in a rails app) in my c:\users\ directory, however was not able to run it anymore after that. I have also deleted all rails related files in that directory and retried, but have had no success. Please

问题 //TeamSize is an integer int Seg_id = shmget(SHM_KEY,sizeof(Word)*TeamSize,IPC_CREAT); void* Seg_ptr = shmat(Seg_id,0,0); new(Seg_ptr) Word[TeamSize]; I am having trouble with this segment of code. The Word class is a class that I defined with 8 bytes char array and some parse functions. I think I am using shmget and shmat just like how others use them. But I keep getting seg fault. When I print out Seg_id, it looks normal just some number. But Seg_ptr points at 0xffffffffffffffff. Then the

问题 Situation I am writing a memory manager for dynamic memory (de)allocations. For a class A to use it when operator new (or delete ) is called, it is sufficient for class A to inherit from a class CustomAllocate , which itself overloads new and delete in a way that uses the memory manager. Problem However, apparently I completely missed out on alignment requirements. Unfortunately, CustomAllocate::new has no information about how a class A inheriting from it should be aligned as the only

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: How do you realloc in C++? I know that C++ arrays can be reallocated (expanded) using realloc() if memory has been allocated via malloc() or calloc() . My question is, how can I expand an array in C++ whose memory has been allocated via the new operator? 回答1: You can't - that's why in C++ you use std::vector<> . If you wanted to do this, you'd have to allocate a new array (via new ), then copy the old items

问题 So I am starting to learn C#, like literally just started learning, and coming from a Java background, it doesn't look too bad. However, I have a question. I am following THIS tutorial on using the client-object model. And just starting from the top, I added the references, but using Microsoft.SharePoint.Client; keeps giving me the error that "the namespace 'SharePoint' does not exist in the namespace 'Microsoft', but I clearly see it on the right side panel. So looking at the instructions,

问题 In our iPhone XCode 3.2.1 project, we're linking in 2 external static C++ libraries, libBlue.a and libGreen.a. libBlue.a globally overrides the " new " operator for it's own memory management. However, when we build our project, libGreen.a winds up using libBlue's new operator, which results in a crash (presumably because libBlue.a is making assumptions about the kinds of structures being allocated). Both libBlue.a and libGreen.a are provided by 3rd parties, so we can't change any of their

问题 In our iPhone XCode 3.2.1 project, we're linking in 2 external static C++ libraries, libBlue.a and libGreen.a. libBlue.a globally overrides the " new " operator for it's own memory management. However, when we build our project, libGreen.a winds up using libBlue's new operator, which results in a crash (presumably because libBlue.a is making assumptions about the kinds of structures being allocated). Both libBlue.a and libGreen.a are provided by 3rd parties, so we can't change any of their