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Using erase_If with Set in C++ STL

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  • Last Updated : 27 Nov, 2022
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The erase_if function in C++20  is used to erase all the elements in the set satisfying the required condition. This condition is referred to as the predicate

The syntax for the erase_if function is 

erase_if(set, predicate);

The first argument of erase function is the set in which elements need to be erased. The second argument is the predicate which is the condition to be satisfied.

Example:

In this example, we are considering a set of the first 10 natural numbers and using the erase_if function to erase all odd elements from the set.

C++




#include <bits/stdc++.h>
using namespace std;
  
int main()
{
  
    set<int> data = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
    cout << "Original set: " << endl;
    for (auto e : data)
        cout << e << " ";
    cout << endl;
    
  // predicate (the condition to be satisfied to erase elements)
    auto remove_odd
        = [](auto const& x) { return (x % 2) == 0; };
    
  // calling erase_if function
    erase_if(data, remove_odd);
    cout << "After removing odd elements from the set "
            "using erase_if\n";
    for (auto e : data)
        cout << e << " ";
    cout << endl;
    return 0;
}


Output:

Original set: 
1 2 3 4 5 6 7 8 9 10 
After removing odd elements from the set using erase_if
1 3 5 7 9 

Note: erase_if function is available in C++20 and GeeksForGeeks Compiler supports only till C++14 thus you will get an error if you will try running code here. 

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