auto

  1. auto不能识别含两个及以上double的类型，e.g.std::pair<double,double> or std::vector<double>
  2. 若类型名太长且引用次数多，可使用别名using
  3. auto常用于for循环计数变量，e.g.
std::vector vec {1,2,3,4};
for(auto elem : vec){
    std::cout << elem << " ";
}
  1. auto常用于函数传参，使函数可以接受任意类型的参数，e.g.
void  borges(auto cuento){
    std::cout << cuento << std::endl;
}

borges(std::string{"el sur"});//auto deduced as `std::string`

初始化变量

  1. 初始化变量可以使用std::vector或std::map进行统一初始化，也可以进行结构化绑定(Structured Binding)（需要已知变量数，不可用于std::vector一类）
//统一初始化
#include 
int main() {
    std::vector v{1, 2, 3, 4, 5};
    return 0;
}
---
#include 
#include 
int main() {
    std::map ages{
        {"Alice", 25},
        {"Bob", 30},
        {"Charlie", 35}
    };

    // Accessing map elements
    std::cout << "Alice's age: " << ages["Alice"] << std::endl;
    std::cout << "Bob's age: " << ages.at("Bob") << std::endl;
    return 0;
}

//结构化绑定
auto [var1, var2, ..., varN] = expression;
---
std::tuple getClassInfo() {
    std::string className = "CS106L";
    std::string location = "online";
    std::string language = "C++";
    return {className, location, language};
}
int main() {
    auto [className, location, language] = getClassInfo();
    std::cout << "Join us " << location << " for " << className << " to learn " << language << "!" << std::endl;
    return 0;
}

 

四山便是清凉国，一室可为安乐窝
最后更新于 2025-07-13