很多语言都有Range-based for loops这个功能,现在C++终于知道把这个重要功能加进语法中了。这个功能实在不知道该怎么翻译,语文没有学到家。 基本语法 for ( range_declaration : range_expression) loop_statement 1. 比如说: 1. vector<int> vec; 2. vec.push_back( 1 ); 3. vec.push_back( 2 ); 4. ...
遍历一个map,for循环中val的类型是std::pair;所以对于map这种关联性容器而言,可以使用val.first来提取键值 #include <iostream> #include <string> #include <vector> using namespace std; int main(){ map<string,int> ma={ {"1",1},{"2",2},{"3",3} }; for(auto val : ma){ cout<<val.fi...
template<typenameT, std::size_tN>begin(T(&a)[N]) {returna; }//参数:数组的引用template<typenameT, std::size_tN>end(T(&a)[N]) {returna + N; } 使用range-based for 对 map 的遍历方法: #include<iostream> #include<map> intmain(void) { std::map<std::string, int>mm= { {"1"...
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...
C++ Range-based loop: Here, we are going to learn about the range-based loop in C++, which is similar to the for-each loop.
map<string,int>m{{"a",1},{"b",2},{"c",3}};for(std::map<string,int>::iterator it=m.begin();it!=m.end();it++){std::cout<<it->first<<":"<<it->second<<std::endl;} 通过共同使用auto以及新的for循环,可以使我们减少对于类型的关注,进而将更多的注意力放在函数功能的实现上。
namespace std; // forward-declaration to allow use in Iter class IntVector; class Iter { public: Iter (const IntVector* p_vec, int pos) : _pos( pos ) , _p_vec( p_vec ) { } // these three methods form the basis of an iterator for use with // a range-based for loop bool...
for(std::map<int, set<std::string> >::iterator t : map_thing) {… } C++ CopyYou would say:for(auto t : map_thing) {… } C++ CopyLimitationsThere are two minor limitations to note when using this for loop format:There is no index variable. If your loop operation requires an ...
loop_statement - any statement, typically a compound statement, which is the body of the loop range_declaration may be a structured binding declaration. for (auto&& first,second : mymap) { // use first and second } (since C++17) 解释 以上语法生成的代码相当于以下%28__range,,,__begin和...
42. TMAP和MAP数据结构(42. TMAP and map Data Structures) 43. 基于循环的范围(43. Range-based for Loop) 44. 设计辅助函数(44. Design a Helper Function) 45. YOR游戏测试(45. Playtesting Yor Game) 46. 困难& 播放调谐(46. Difficulty & Play Tuning) 47. 抛光& 包装(47. Polishing & Packaging...