constexpr T value_or( U&& default_value ) &&; (2) (C++17 起) 若*this 含值则返回其所含的值,否则返回 default_value。 1) 等价于 bool(*this) ? **this : static_cast<T>(std::forward<U>(default_value))。2) 等价于 bool(*this) ? std::move(**this) : static_cast<T>(std::for...
std::optional<T>::value_or template<classU> constexprT value_or(U&&default_value)const&; (1)(since C++17) template<classU> constexprT value_or(U&&default_value)&&; (2)(since C++17) Returns the contained value if*thishas a value, otherwise returnsdefault_value. ...
std::experimental::optional<T>::value_or From cppreference.com <cpp |experimental |optional Library fundamentals experimental::optional experimental::any experimental::basic_string_view experimental::sample experimental::shared_ptr experimental::weak_ptr ...
String surname = "Doe"; // 假设默认姓氏为Doe Serial.println("Enter your surname (or just press Enter to use default surname Doe):"); if (Serial.available() > 0) { surname = Serial.readString(); // 从串口读取输入的姓氏 } Serial.print(name); Serial.print(" "); Serial.print(surname...
glvalue(泛左值) = lvalue (传统意义上的左值)+ xvalue(消亡值,通过右值引用产生) rvalue (传统意义上的右值) = prvalue(纯右值) + xvalue Primary categories 1. lvalue(左值) The following expressions are lvalue expressions: the name of a variable or a function in scope, regardless of type, suc...
std::optional<std::string> create(bool b) { if (b) { return "Godzilla"; } else { return {}; } } create(false).value_or("empty"); // == "empty" create(true).value(); // == "Godzilla" // optional-returning factory functions are usable as conditions of while and if if (au...
A common use case for optional is the return value of a function that may fail. std::optional<std::string> create(bool b) { if (b) { return "Godzilla"; } else { return {}; } } create(false).value_or("empty"); // == "empty" create(true).value(); // == "Godzilla" //...
t perform null checks here.value.ToString();}}public string PropertyWithNullChecksDisabledOnGetterOnly{[Il2CppSetOption(Option.NullChecks,false)]get{// Unity doesn’t perform null checks here.var tmp=newobject();returntmp.ToString();}set{// Unity performs null checks here.value.ToString();}}...
-fp-model=strictTells the compiler to strictly adhere to value-safe optimizations. -fp-speculation=safe/fast/strict/offare all supported. There is no support for #pragma fenv_access. The math library related features in ICC are currently being ported to ICX. We have implemented the IMF (In...
If the image is16-bit unsignedor32-bit integer, the pixels aredivided by 256(缩小256,不是255) .That is, the value range [0,255*256] is mapped to[0,255]. 我实验中,type(某图的某元素)输出class numpy.int16。我还把这张图的像素值,限制255一下: ...