Khóa học C++ từ cơ bản đến nâng cao

#include <map>
#include <string> // Để sử dụng string
#include <iostream> // Để in ra console

int main() {
    // Khai báo một map lưu tên (string) và tuổi (int)
    map<string, int> age_map;
    cout << "Da khai bao age_map." << endl;

    // Khai báo một map lưu mã sản phẩm (int) và tên sản phẩm (string)
    map<int, string> product_catalog;
    cout << "Da khai bao product_catalog." << endl;

    // Khai báo một map lưu chữ cái (char) và tần suất xuất hiện (int)
    map<char, int> frequency_counter;
    cout << "Da khai bao frequency_counter." << endl;

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;

    // Them moi
    age_map["Alice"] = 30; // Alice chua ton tai, them moi {Alice, 30}
    age_map["Bob"] = 25;   // Bob chua ton tai, them moi {Bob, 25}

    // Cap nhat gia tri cho khoa da ton tai
    age_map["Alice"] = 31; // Alice da ton tai, cap nhat gia tri tu 30 thanh 31

    // Luu y: Truyen khoa chua ton tai vao [] de doc co the gay ra viec them moi ngam!
    // int chieu_cao_david = age_map["David"]; // David chua ton tai, map se them {David, 0}
    // cout << "Tuoi cua David (co the bi them moi): " << age_map["David"] << endl; // David co gia tri mac dinh 0

    return 0;
}

#include <map>
#include <string>
#include <iostream>
#include <utility> // De su dung pair

int main() {
    map<string, string> phone_book;

    // Them moi su dung insert voi pair
    pair<string, string> entry1("Alice", "0912345678");
    auto result1 = phone_book.insert(entry1);
    if (result1.second) {
        cout << "Da them Alice vao danh ba." << endl;
    } else {
        cout << "Alice da co trong danh ba." << endl;
    }

    // Them moi su dung insert voi initializer list (C++11 tro len)
    auto result2 = phone_book.insert({"Bob", "0987654321"});
    if (result2.second) {
        cout << "Da them Bob vao danh ba." << endl;
    } else {
        cout << "Bob da co trong danh ba." << endl;
    }

    // Thu them lai Alice (da co trong map)
    auto result3 = phone_book.insert({"Alice", "0900000000"}); // So dien thoai moi
    if (result3.second) {
        cout << "Da them Alice lan 2 (se khong xay ra)." << endl;
    } else {
        // second == false vi Alice da ton tai.
        // first la iterator tro den phan tu {Alice, "0912345678"}
        cout << "Alice da co trong danh ba. Khong cap nhat so dien thoai moi." << endl;
        cout << "So hien tai cua Alice: " << result3.first->second << endl;
    }

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, double> item_prices;

    // Su dung emplace de them cap khoa-gia tri
    auto result1 = item_prices.emplace("Apple", 1.2);
    if (result1.second) {
        cout << "Da them gia Apple." << endl;
    }

    auto result2 = item_prices.emplace("Banana", 0.75);
    if (result2.second) {
        cout << "Da them gia Banana." << endl;
    }

    // Thu emplace lai Apple
    auto result3 = item_prices.emplace("Apple", 1.5); // Gia moi
     if (!result3.second) {
        cout << "Apple da co trong map. Khong cap nhat gia moi." << endl;
        cout << "Gia hien tai cua Apple: " << result3.first->second << endl;
    }

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;

    // Truy cap gia tri bang khoa ton tai
    int alice_age = age_map["Alice"];
    cout << "Tuoi cua Alice: " << alice_age << endl; // Output: 30

    // Truy cap gia tri bang khoa KHONG ton tai (CAN THAN!)
    // int charlie_age = age_map["Charlie"]; // Charlie chua ton tai, map se them {Charlie, 0}
    // cout << "Tuoi cua Charlie (sau khi truy cap bang []): " << age_map["Charlie"] << endl; // Output: 0

    // Kich thuoc map truoc va sau khi truy cap khoa khong ton tai
    // cout << "Kich thuoc map truoc: 2" << endl;
    // age_map["Charlie"]; // Them Charlie
    // cout << "Kich thuoc map sau: " << age_map.size() << endl; // Output: 3

    return 0;
}

#include <map>
#include <string>
#include <iostream>
#include <stdexcept> // De su dung out_of_range

int main() {
    map<string, int> age_map;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;

    // Truy cap gia tri bang khoa ton tai (an toan)
    try {
        int bob_age = age_map.at("Bob");
        cout << "Tuoi cua Bob: " << bob_age << endl; // Output: 25
    } catch (const out_of_range& e) {
        cerr << "Loi: " << e.what() << endl; // Khong xay ra trong truong hop nay
    }

    // Truy cap gia tri bang khoa KHONG ton tai (se nem ngoai le)
    try {
        int charlie_age = age_map.at("Charlie"); // Charlie chua ton tai
        cout << "Tuoi cua Charlie: " << charlie_age << endl; // Dong nay se khong chay
    } catch (const out_of_range& e) {
        cerr << "Loi: Khong tim thay Charlie trong map! Thong bao: " << e.what() << endl;
        // Output: Loi: Khong tim thay Charlie trong map! Thong bao: map::at
    }

    // Kich thuoc map sau khi dung at() voi khoa khong ton tai
    cout << "Kich thuoc map sau khi dung at() voi Charlie: " << age_map.size() << endl; // Output: 2 (Charlie khong bi them vao)

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;
    age_map["Charlie"] = 35;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;

    cout << "Duyet map su dung range-based for loop:" << endl;
    // Moi phan tu trong map la mot pair<const KeyType, ValueType>
    for (const auto& pair : age_map) {
        // pair.first la khoa (string)
        // pair.second la gia tri (int)
        cout << pair.first << " is " << pair.second << " years old." << endl;
    }
    // Output thu tu:
    // Alice is 30 years old.
    // Bob is 25 years old.
    // Charlie is 35 years old.

    cout << "\nDuyet map su dung iterator:" << endl;
    for (auto it = age_map.begin(); it != age_map.end(); ++it) {
        // it la mot iterator tro toi pair<const KeyType, ValueType>
        // it->first la khoa
        // it->second la gia tri
        cout << it->first << ": " << it->second << endl;
    }
    // Output thu tu:
    // Alice: 30
    // Bob: 25
    // Charlie: 35

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;

    // Kiem tra su ton tai cua Alice
    if (age_map.count("Alice")) {
        cout << "Alice is in the map." << endl;
    } else {
        cout << "Alice is not in the map." << endl; // Khong chay
    }

    // Kiem tra su ton tai cua Charlie
    if (age_map.count("Charlie")) {
        cout << "Charlie is in the map." << endl; // Khong chay
    } else {
        cout << "Charlie is not in the map." << endl;
    }

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;

    // Tim Alice
    auto it_alice = age_map.find("Alice");
    if (it_alice != age_map.end()) {
        cout << "Found Alice! Age: " << it_alice->second << endl; // Output: Found Alice! Age: 30
    } else {
        cout << "Alice not found." << endl; // Khong chay
    }

    // Tim Charlie
    auto it_charlie = age_map.find("Charlie");
    if (it_charlie != age_map.end()) {
        cout << "Found Charlie! Age: " << it_charlie->second << endl; // Khong chay
    } else {
        cout << "Charlie not found." << endl;
    }

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;
    age_map["Charlie"] = 35;

    cout << "Map ban dau co " << age_map.size() << " phan tu." << endl; // Output: 3

    // Xoa Bob bang khoa
    size_t removed_count = age_map.erase("Bob");
    if (removed_count > 0) {
        cout << "Da xoa Bob. Con " << age_map.size() << " phan tu." << endl; // Output: Da xoa Bob. Con 2 phan tu.
    }

    // Thu xoa David (khong ton tai)
    size_t removed_david = age_map.erase("David");
    if (removed_david == 0) {
        cout << "David khong co trong map, khong xoa duoc." << endl; // Output: David khong co trong map, khong xoa duoc.
    }

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;
    age_map["Charlie"] = 35;

    // Tim Bob
    auto it_bob = age_map.find("Bob");

    // Xoa Bob bang iterator
    if (it_bob != age_map.end()) {
        // Luu y: erase(iterator) tra ve iterator den phan tu tiep theo
        auto it_next = age_map.erase(it_bob);
        cout << "Da xoa Bob bang iterator." << endl;
        if (it_next != age_map.end()) {
             cout << "Phan tu tiep theo la: " << it_next->first << endl; // Output: Phan tu tiep theo la: Charlie
        }
    }

    cout << "Map hien tai co " << age_map.size() << " phan tu." << endl; // Output: 2

    return 0;
}

#include <map>
#include <string>
#include <iostream>

int main() {
    map<string, int> age_map;
    age_map["Alice"] = 30;
    age_map["Bob"] = 25;

    cout << "Kich thuoc ban dau: " << age_map.size() << endl; // Output: 2
    cout << "Map co rong khong? " << (age_map.empty() ? "Co" : "Khong") << endl; // Output: Khong

    age_map.clear(); // Xoa het cac phan tu

    cout << "Kich thuoc sau khi clear: " << age_map.size() << endl; // Output: 0
    cout << "Map co rong khong sau clear? " << (age_map.empty() ? "Co" : "Khong") << endl; // Output: Co

    return 0;
}

#include <iostream>
#include <map>
#include <string>
#include <sstream> // De tach chuoi thanh tu
#include <cctype> // De xu ly ky tu (chuyen thanh chu thuong)
#include <algorithm> // De su dung transform

int main() {
    string text = "This is a sample text. This text is a sample.";
    map<string, int> word_counts;

    // Tao mot stringstream tu chuoi van ban
    stringstream ss(text);
    string word;

    // Doc tung tu tu stringstream
    while (ss >> word) {
        // Don gian hoa tu: chuyen thanh chu thuong va loai bo dau cham, phay
        transform(word.begin(), word.end(), word.begin(),
                       [](unsigned char c){ return tolower(c); });

        // Loai bo cac ky tu dac biet o cuoi tu (vi du: dau cham)
        while (!word.empty() && ispunct(word.back())) {
            word.pop_back();
        }

        // Neu tu khong rong, tang bien dem trong map
        if (!word.empty()) {
            word_counts[word]++; // Day la dieu ky dieu cua map!
        }
    }

    // In ket qua (map tu dong sap xep theo tu)
    cout << "Tan suat xuat hien cua cac tu:" << endl;
    for (const auto& pair : word_counts) {
        cout << pair.first << ": " << pair.second << endl;
    }
    /* Output (co the khac tuy vao cach xu ly chuan hoa tu):
    a: 2
    is: 2
    sample: 2
    text: 2
    this: 2
    */

    return 0;
}