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 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, ...
continue语句来开始下一次迭代,使用break跳出循环。这一点和普通的for循环一样。 深入分析 1. for ( range_declaration : range_expression) loop_statement 1. “等价于” 1. { 2. auto && __range = range_expression ; 3. auto __begin = begin_expr(__range); 4. auto __end = end_expr(__ran...
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)实际上等价于下面的for循环: > `for ( item-declaration : range-initializer...
(__range,__beginand__endare for exposition only): { auto&& __range =range_expression ;for(auto __begin = begin_expr, __end =end_expr; __begin!= __end; ++__begin) { range_declaration= *__begin; 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...
for(inti:{1,2,3})inti=1;// error: redeclaration Temporary range initializer Ifrange-initializerreturns a temporary, its lifetime is extended until the end of the loop, as indicated by binding to the forwarding reference/* range */.
; for (auto &c : s) { /* ... */ } 直觉上c的类型应该是const char&,但是怎么推理得到c的类型呢?细究起来确实花了一番功夫。 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(...
The range-based for loop follows this general format:for( declaration : expression) { //do some loop stuff } C++ CopyHere’s an simple example which prints all the elements in a std::vector:std::vector<int> v1 = {-1, 3, 5, -8, 0}; std::cout << std::endl << "v1: " <...
C++11 引入了 range-based for loop,作为对旧有遍历方式的扩展和简化,旨在提高代码的可读性和安全性。 3. 说明 [-wc++11-extensions] 编译器标志的含义 -Wc++11-extensions 是GCC 编译器的一个警告标志,用于提示代码中使用了 C++11 的扩展特性。当你在编译 C++ 代码时,如果启用了这个警告标志,并且代码中使用...
Finally, C++ has the same concept; you can provide a container to your for loop, and it will iterate over it. We've already seen a few basic examples in What is C++11? To refresh your memory, the range-based for loop looks like this: ...