c_cpp CPP - 教程018 - 关联容器和容器适配器

Posted 2021-05-14

// ----- ASSOCIATIVE CONTAINERS -----
// Associative containers store sorted data 
// which makes insertion slower, but searching
// faster

int main()
{
    // ----- SET -----
    // Sets store unique sorted values using a key
    std::set<int> set1 {5,4,3,2,1,1};
    std::cout << "Size : " << set1.size() <<
            "\n";
    
    // Insert value
    set1.insert(0);
    
    // Subscript operator doesn't work
    // std::cout << set1[0] << "\n";
    
    // Get values with an iterator
    std::set<int>::iterator it = set1.begin();
    it++;
    
    std::cout << "2nd : " << *it << "\n";
    
    // Erase value
    set1.erase(5);
    
    // Erase last 2
    it = set1.end();
    std::advance(it, -2);
    set1.erase(it, set1.end());
    
    // Add multiple values
    int arr[] = {6,7,8,9};
    set1.insert(arr,arr+4);
    
    // Find value, get iterator and then value
    auto val = set1.find(6);
    std::cout << "Found : " << *val << "\n";
    
    // Get iterator to value
    auto eight = set1.lower_bound(8);
    std::cout << "8 : " << *eight << "\n";
    
    // Get iterator to value after
    auto nine = set1.upper_bound(8);
    std::cout << "9 : " << *nine << "\n";
    
    // Swap values in sets
    std::set<int> set2 {10,11};
    set1.swap(set2);
    
    // Check if empty and if not print values
    if(!set1.empty()){
        for(int i : set1)
        std::cout << i << "\n";
    }
    
    // ----- END OF SET -----
    
    std::cout << "\n";
    
    // ----- MULTISET -----
    // Stores duplicate values in sorted order
    // Other than that it is the same as set
    std::multiset<int> mset1 {1,1,2,3,4};
    
    // Insert value
    mset1.insert(4);
    mset1.insert(0);
    
    if(!mset1.empty()){
        for(int i : mset1)
        std::cout << i << "\n";
    }
    
    // ----- END MULTISET -----
    
    std::cout << "\n";
    
    // ----- MAP -----
    // Stores using key value pairs and you
    // can't have duplicate keys
    std::map<int, std::string> map1;
    
    // Insert key values
    map1.insert(std::pair <int, std::string> (1, "Bart"));
    map1.insert(std::pair <int, std::string> (2, "Lisa"));
    map1.insert(std::pair <int, std::string> (3, "Marge"));
    map1.insert(std::pair <int, std::string> (4, "Homer"));
    
    // Find element by key
    auto match = map1.find(1);
    std::cout << match->second << "\n";
    
    // Get iterator to value
    auto bart = map1.lower_bound(1);
    std::cout << "LB : " << bart->second << "\n";
    
    // Get next iterator
    auto lisa = map1.upper_bound(1);
    std::cout << "UB : " << lisa->second << "\n";
    
    // Print elements with an iterator
    std::map<int, std::string>::iterator it2;
    for(it2 = map1.begin(); it2 != map1.end(); ++it2){
        std::cout << "Key : " << it2->first << "\n";
        std::cout << "Value : " << it2->second << "\n";
    }
    
    // ----- END OF MAP -----
    
    // ----- MULTIMAP -----
    // Like map except you can have duplicate keys as long
    // as the values are different
    std::multimap<int, std::string> mmap1;
    mmap1.insert(std::pair <int, std::string> (1, "Bart"));
    mmap1.insert(std::pair <int, std::string> (1, "Lisa"));
    mmap1.insert(std::pair <int, std::string> (3, "Marge"));
    std::map<int, std::string>::iterator it3;
    for(it3 = mmap1.begin(); it3 != mmap1.end(); ++it3){
        std::cout << "Key : " << it3->first << "\n";
        std::cout << "Value : " << it3->second << "\n";
    }
    
    // ----- END OF MULTIMAP -----
    
    // ----- CONTAINER ADAPTERS -----
    // Adapt containers to provide a defined interface
    
    // ----- STACK -----
    // Provides an interface for storing elements in a LIFO
    // format
    std::stack<std::string> custs;
    custs.push("George");
    custs.push("Louise");
    custs.push("Florence");
    
    // Get number of elements
    int size = custs.size();
    
    // Check if empty
    if(!custs.empty()){
        for(int i = 0; i < size; i++){
            
            // Get value with top
            std::cout << custs.top() << "\n";
            
            // Delete last value entered
            custs.pop();
        }
    }
        
    // ----- END OF STACK -----
    
    // ----- QUEUE -----
    // Provides an interface for storing elements in a FIFO
    // format
    std::queue<std::string> cast;
    cast.push("Zoidberg");
    cast.push("Bender");
    cast.push("Leela");
    int size2 = cast.size();
    
    if(!cast.empty()){
        for(int i = 0; i < size2; i++){
            
            // Get value with top
            std::cout << cast.front() << "\n";
            
            // Delete last value entered
            cast.pop();
        }
    }
    
    // ----- END OF QUEUE -----
    
    // ----- PRIORITY QUEUE -----
    // Elements are organized with the largest first
    std::priority_queue<int> nums;
    nums.push(4);
    nums.push(8);
    nums.push(5);
    int size3 = nums.size();
    
    if(!nums.empty()){
        for(int i = 0; i < size3; i++){
            
            // Get value with top
            std::cout << nums.top() << "\n";
            
            // Delete last value entered
            nums.pop();
        }
    }
    
    // ----- END OF PRIORITY QUEUE -----
    
    // ----- ENUMS -----
    // Custom data type that assigns names to 
    // constant integers so that a program is
    // easier to read
    
    // You can define the starting index, or any others
    enum day{Mon=1, Tues, Wed, Thur, Fri=5};
    
    enum day tuesday = Tues;
    
    std::cout << "Tuesday is the " << tuesday <<
            "nd day of the week\n";
    
    // Cycle through days
    for(int i = Mon; i <= Fri; i++)
        std::cout << i << "\n";
    
    // ----- END OF ENUMS -----
    
    return 0;
}