auto

问题 Why doesn't defining a variable with auto keyword carry the constexpr 'ness of the expression used to initialize it? As an example, consider the following code: #include <string_view> constexpr std::string_view f() { return "hello"; } static constexpr std::string_view g() { constexpr auto x = f(); // (*) return x.substr(1, 3); } int foo() { return g().length(); } With GCC 10.2 and --std=c++20 -fsanitize=undefined -O3 , this compiles into: foo(): mov eax, 3 ret But if we remove the constexpr

问题 C++14 supports generic lambdas. However, the following code is rejected by clang 3.4. #include <utility> void f(int); void f(int&); int main() { [](auto&& v) { f(std::forward<auto>(v)); }(8); // error } How to perfectly forward auto&& in a generic lambda? 回答1: auto is not a type so I’m not surprised this doesn’t work. But can’t you use decltype ? [](auto&& v) { f(std::forward<decltype(v)>(v)); }(8); Scott Meyers has more details. 来源： https://stackoverflow.com/questions/24535430/how-to

问题 C++14 supports generic lambdas. However, the following code is rejected by clang 3.4. #include <utility> void f(int); void f(int&); int main() { [](auto&& v) { f(std::forward<auto>(v)); }(8); // error } How to perfectly forward auto&& in a generic lambda? 回答1: auto is not a type so I’m not surprised this doesn’t work. But can’t you use decltype ? [](auto&& v) { f(std::forward<decltype(v)>(v)); }(8); Scott Meyers has more details. 来源： https://stackoverflow.com/questions/24535430/how-to

问题 (This question has been broken out from the discussion to this answer, which highlights CWG 1892) Some paragraphs of the standard applies specific rules to function declarators ; e.g. [dcl.spec.auto]/3 regarding placeholder types [ emphasis mine]: The placeholder type can appear with a function declarator in the decl-specifier-seq , type-specifier-seq , conversion-function-id , or trailing-return-type , in any context where such a declarator is valid. If the function declarator includes a

问题 Please considere the following code-snippet: #include <iostream> void print(auto arg) { std::cout << arg << std::endl; } int main() { print("Hi"); return 0; } As you can see here (https://godbolt.org/z/2GSrXs) using GCC the code compiles and runs fine. As you can see here (https://godbolt.org/z/rtR6w9) using Visual C++ the code does not compile and results in the error message: <source>(3): error C3533: a parameter cannot have a type that contains 'auto' . It seems to me that this feature has

问题 Please considere the following code-snippet: #include <iostream> void print(auto arg) { std::cout << arg << std::endl; } int main() { print("Hi"); return 0; } As you can see here (https://godbolt.org/z/2GSrXs) using GCC the code compiles and runs fine. As you can see here (https://godbolt.org/z/rtR6w9) using Visual C++ the code does not compile and results in the error message: <source>(3): error C3533: a parameter cannot have a type that contains 'auto' . It seems to me that this feature has

问题 I just trained a Google Auto ML Vision model and exported as TensorFlowJS to implement it in React Native. The Problem I am facing: Google splits the weights into 6 different shard*.bin files. As it is a graph model, I can't use the tensorflowjs_converter to leverage the --weight_shard_size_bytes setting. I did not find any other way to import it into my React Native app than by using the BundleResourcesIO function which needs one bin file. The model should be bundled locally. Does anyone

问题 This question already has answers here : Why floating point value such as 3.14 are considered as double by default in MSVC? (5 answers) All floats are doubles? (3 answers) How a floating point literal is treated either double or float in Visual C++? (2 answers) why sizeof(13.33) is 8 bytes? (5 answers) What is the type of the value 1.0e+1 (4 answers) Closed 1 year ago . In the snippet below, auto deduces the variable to double , but I want float . auto one = 3.5; Does it always use double for

问题 This question already has answers here : Why floating point value such as 3.14 are considered as double by default in MSVC? (5 answers) All floats are doubles? (3 answers) How a floating point literal is treated either double or float in Visual C++? (2 answers) why sizeof(13.33) is 8 bytes? (5 answers) What is the type of the value 1.0e+1 (4 answers) Closed 1 year ago . In the snippet below, auto deduces the variable to double , but I want float . auto one = 3.5; Does it always use double for

问题 Hey my StackView is doing nothing, there are two problems: The first is that the elements on the VC are completely displaced when I turn around the simulator or change the device, so the StackView is not doing what it should do! The second thing is that the StackView is covering the navigation bar and I don't know how to make it visible. Can someone help me? import UIKit class RegisterViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate { let