Insertion and Deletion in STL Set C++

Insertion (การแทรก)

Insertion ใน STL set สามารถทำได้โดย insert() และ emplace() operation

Insert(): Insert() ใช้เพื่อแทรก elements ลงใน set Insert operation รับ reference ไปยัง object

List of functions are used:

• st.size() = Returns the size of set.
• st.insert() = It is used to insert elements to the set.

ตัวอย่างโค้ด

#include <iostream>
#include <set>
#include <string>
#include <cstdlib>
using namespace std;
int main() {
    set<int> st;
    set<int>::iterator it;
    int c, i;
    while (1) {
        cout<<"1.Size of the Set"<<endl;
        cout<<"2.Insert Element into the Set"<<endl;
        cout<<"3.Display the set: "<<endl;
        cout<<"4.Exit"<<endl;
        cout<<"Enter your Choice: ";
        cin>>c;
        switch(c) {
            case 1:
                cout<<"Size of the Set: ";
                cout<<st.size()<<endl;
                break;
            case 2:
                cout<<"Enter value to be inserted: ";
                cin>>i;
                st.insert(i);
                break;
            case 3:
                cout<<"Displaying Set by Iterator: ";
                for (it = st.begin(); it != st.end(); it++) {
                    cout << (*it)<<" ";
                }
                cout<<endl;
                break;
            case 4:
                exit(1);
                break;
            default:
                cout<<"Wrong Choice"<<endl;
        }
    }
    return 0;
}

ผลลัพธ์

1.Size of the Set
2.Insert Element into the Set
3.Display the set:
4.Exit
Enter your Choice: 1
Size of the Set: 0
...
Displaying Set by Iterator: 4 6 8 10
1.Size of the Set
2.Insert Element into the Set
3.Display the set:
4.Exit
Enter your Choice: 4
Exit code: 1

Emplace()

Emplace operation ใช้แทรก elements ลงใน set แบบ in-place มันหลีกเลี่ยงการ copy object ที่ไม่จำเป็น และทำ insertion ได้มีประสิทธิภาพมากกว่า insert operation

List of functions used:

• st.size() = Returns the size of set.
• st.emplace() = It is used to insert elements to the set.

ตัวอย่างโค้ด

#include <iostream>
#include <set>
#include <string>
#include <cstdlib>
using namespace std;
int main() {
    set<int> st;
    set<int>::iterator it;
    int c, i;
    while (1) {
        cout<<"1.Size of the Set"<<endl;
        cout<<"2.Insert Element into the Set"<<endl;
        cout<<"3.Display the set: "<<endl;
        cout<<"4.Exit"<<endl;
        cout<<"Enter your Choice: ";
        cin>>c;
        switch(c) {
            case 1:
                cout<<"Size of the Set: ";
                cout<<st.size()<<endl;
                break;
            case 2:
                cout<<"Enter value to be inserted: ";
                cin>>i;
                st.emplace(i);
                break;
            case 3:
                cout<<"Displaying Set by Iterator: ";
                for (it = st.begin(); it != st.end(); it++) {
                    cout << (*it)<<" ";
                }
                cout<<endl;
                break;
            case 4:
                exit(1);
                break;
            default:
                cout<<"Wrong Choice"<<endl;
        }
    }
    return 0;
}

ผลลัพธ์

1.Size of the Set
2.Insert Element into the Set
3.Display the set:
4.Exit
Enter your Choice: 1
Size of the Set: 0
...
Displaying Set by Iterator: 4 6 7 8
1.Size of the Set
2.Insert Element into the Set
3.Display the set:
4.Exit
Enter your Choice: 4
Exit code: 1

Deletion (การลบ)

ใช้ erase() function เราสามารถลบ elements จาก set ได้โดยระบุ argument หรือเป็นตำแหน่ง ค่า หรือช่วงของตัวเลข

List of functions used here:

• st.size() = Returns the size of set.
• st.insert() = It is used to insert elements to the set.
• st.erase() = To delete the element from the set

ตัวอย่างโค้ด

#include <iostream>
#include <set>
#include <string>
#include <cstdlib>
using namespace std;
int main() {
    set<int> st;
    set<int>::iterator it;
    int c, i;
    while (1) {
        cout<<"1.Size of the Set"<<endl;
        cout<<"2.Insert Element into the Set"<<endl;
        cout<<"3.Delete Element from the Set"<<endl;
        cout<<"4.Display the set: "<<endl;
        cout<<"5.Exit"<<endl;
        cout<<"Enter your Choice: ";
        cin>>c;
        switch(c) {
            case 1:
                cout<<"Size of the Set: ";
                cout<<st.size()<<endl;
                break;
            case 2:
                cout<<"Enter value to be inserted: ";
                cin>>i;
                st.insert(i);
                break;
            case 3:
                cout<<"Enter the element to be deleted: ";
                cin>>i;
                st.erase(i);
                break;
            case 4:
                cout<<"Displaying Set by Iterator: ";
                for (it = st.begin(); it != st.end(); it++) {
                    cout << (*it)<<" ";
                }
                cout<<endl;
                break;
            case 5:
                exit(1);
                break;
            default:
                cout<<"Wrong Choice"<<endl;
        }
    }
    return 0;
}

ผลลัพธ์

1.Size of the Set
2.Insert Element into the Set
3.Delete Element from the Set
4.Display the set:
5.Exit
Enter your Choice: 1
Size of the Set: 0
...
Displaying Set by Iterator: 1 3 4
1.Size of the Set
2.Insert Element into the Set
3.Delete Element from the Set
4.Display the set:
5.Exit
Enter your Choice: 5
Exit code: 1