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set::clear() function in C++ STL

C++ STL set::clear() function: Here, we are going to learn about the clear() function of set in C++ STL (Standard Template Library).
Submitted by Radib Kar, on February 16, 2019

C++ STL set::clear() function

set::clear() function is a predefined function, it is used to clear the entire set irrespective of its elements.

Syntax

set<T> st; //declaration
st.clear()

Parameter(s)

This function does not accept any parameter.

Return value

This function does not return any value. The function clears the entire set irrespective of its elements.

Sample Input and Output

For a set of integer,
set<int> st;
st.insert(4);
st.insert(5);
set content:
    4
    5

st.clear();  
set content:
empty set

Header file

Header file to be included:

#include <iostream>
#include <set>
OR
#include <bits/stdc++.h>

Example

#include <bits/stdc++.h>
using namespace std;

void printSet(set<int> st) {
  set<int>::iterator it;
  cout << "Set contents are:\n";
  if (st.empty()) {
    cout << "empty set\n";
    return;
  }
  for (it = st.begin(); it != st.end(); it++) cout << *it << " ";
  cout << endl;
}

int main() {
  cout << "Example of clear function\n";
  set<int> st;
  set<int>::iterator it;
  cout << "inserting 4\n";
  st.insert(4);
  cout << "inserting 6\n";
  st.insert(6);
  cout << "inserting 10\n";
  st.insert(10);

  printSet(st);  // printing current set

  cout << "clearing all elements\n";
  st.clear();
  printSet(st);

  return 0;
}

Output

Example of clear function
inserting 4
inserting 6
inserting 10
Set contents are:
4 6 10
clearing all elements
Set contents are:
empty set