How to delete an element from the Set by passing its value in C++

Last Updated : 07 Jan, 2019

Given a Set, the task is to remove the last element from this Set in C++.

Examples:

Input: set = [10 20 30 70 80 90 100 40 50 60],
              valueOfElementToBeDeleted = 100
Output: 10 20 30 40 50 60 70 80 90

Input: set = [1 2 3 4 5],
              valueOfElementToBeDeleted = 3
Output: 1 2 4 5

Sets are a type of associative containers in which each element has to be unique because the value of the element identifies it. The value of the element cannot be modified once it is added to the set, though it is possible to remove and add the modified value of that element.

Approach: In this method, the last element is deleted by using the erase function and calling it with the value of the last element as its argument. If the value of the last element is not known, then use the previous method.

Syntax:

size_type erase (const value_type& valueOfElementToBeDeleted);

Below is the implementation of the above approach:

C++

// C++ program to delete an element 
// of a Set by passing its value 
  
#include <iostream> 
#include <set> 
using namespace std; 
  
// Function to print the set 
void printSet(set<int> myset) 
{ 
  
    // Get the iterator 
    set<int>::iterator it; 
  
    // printing all the elements of the set 
    for (it = myset.begin(); it != myset.end(); ++it) 
        cout << ' ' << *it; 
    cout << '\n'; 
} 
  
// Function to delete the element of set 
void deleteByValue(set<int> myset,  
           int valueOfElementToBeDeleted) 
{ 
  
    // printing all the elements of the set 
    cout << "\nSet originally: "; 
    printSet(myset); 
  
    // Erase the element that is equal to 
    // the value passed as the parameter 
    myset.erase(valueOfElementToBeDeleted); 
  
    // printing all the elements of the set 
    cout << "Set after deleting "
         << valueOfElementToBeDeleted 
         << ": "; 
    printSet(myset); 
} 
  
// Driver code 
int main() 
{ 
    set<int> myset; 
  
    // Get the set 
    for (int i = 1; i < 10; i++) 
        myset.insert(i * 10); 
  
    // Get the valueOfElementToBeDeleted 
    int valueOfElementToBeDeleted = 50; 
  
    // Delete an element from the Set 
    deleteByValue(myset, valueOfElementToBeDeleted); 
  
    return 0; 
} 

Python3

# Python3 program to delete an element of a  
# set by passing of a set by passing its value 
  
# function to print the set 
def printset(myset): 
      
    for i in myset: 
        print(i, end = " ") 
    print()  
  
# function to delete the element of a set 
def deleteByValue(myset, value): 
      
    myset = sorted(myset) 
      
    # printint original value 
    print("Set orginally:", end = " ") 
    printset(myset) 
      
    # Erase the element that is equal to 
    # the value passed as the parameter 
    myset.remove(value) 
      
    # printing all the elements of the set 
    print("Set after deleting", value,  
                        ":", end = " ") 
    printset(myset) 
  
# Driver code 
myset = set() 
  
for i in range(1, 10): 
    myset.add(i * 10) 
  
# Get the valueOfElementToBeDeleted  
value = 50
  
# Delete an element from the Set 
deleteByValue(myset, value); 
  
# This code is contributed 
# by Mohit kumar 29 

Output:

Set originally:  10 20 30 40 50 60 70 80 90
Set after deleting 50:  10 20 30 40 60 70 80 90

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