http://en.cppreference.com/w/cpp/language/range-for 语法: for (range_declaration:range_expression)loop_statement for (一个变量名 : 可迭代范围) { //循环语句 } 变量名的类型可以是:容器元素的类型,容器元素的引用类型,auto { auto && __range =range_expression; for (auto __begin =begin_expr,...
Range-based for loop 在范围上执行for循环。 用作更易读的,相当于传统的用于循环操作范围内的值,例如容器中的所有元素。 句法 attr(optional) for ( range_declaration : range_expression ) loop_statement attr - any number of attributes range_declaration - a declaration of a named variable, ...
With arrays taken care of by the first rule, the second rule makes sure that all the standard containers as well as all the user-defined ones that follow the standard sequence interface will work with range-basedforout of the box. For example, in ODB (an ORM for C++), we have the co...
Range-Based for loop应该是一种语法糖,实际上编译器应该是当成普通的for循环来处理的。 从cppreference(en.cppreference.com/w/c)上可以得到印证。 Range-Based for loop的一般形式(省略了不相关的部分)实际上等价于下面的for循环 for ( item-declaration : range-initializer ) statement item-declaration - a...
使用auto声明的变量必须要给初始值,而这里的语法没有给初始值。Range-Based for loop应该是一种语法糖,实际上编译器应该是当成普通的for循环来处理的。 从cppreference(https://en.cppreference.com/w/cpp/language/range-for)上可以得到印证。 Range-Based for loop的一般形式(省略了不相关的部分)实际上等价于...
When used with a (non-const) object that has copy-on-write semantics, the range-basedforloop may trigger a deep copy by (implicitly) calling the non-constbegin()member function. If that is undesirable (for instance because the loop is not actually modifying the object), it can be avoided...
The last rule (the fallback to the free-standingbegin()andend()functions) allows us to non-invasively adapt an existing container to the range-basedforloop interface. 0.2 类型推断 std::vector<int> v = {1, 2, 3, 5, 7, 11};
1. 解释什么是 range-based for loop range-based for loop 是 C++11 引入的一种新的循环结构,用于遍历容器(如数组、vector、list、set、map 等)中的元素。它的语法非常简洁,使得遍历容器变得更加直观和易读。 基本语法如下: cpp for (declaration : container) { // 循环体 } 示例代码: cpp #include &...
One of the more frequently used C++ constructs I use is the range-based for loop. The range-based forloop format was introduced in C++11, so you’ll need to enable that language set (or newer) to reap the benefits. This feature simplifies the verbosity of for loop constructs and is jus...
loop_statement } } range_expression被用于确定将要迭代的序列或范围。序列中的每个元素被解引用,并赋值给由range_declaration指定的变量。 迭代器begin_expr和end_expr可以被定义成如下类型: * 如果__range是数组,(__range)和(__range+__bound)表示数组的范围 ...