What is std::vector::clear() in C++?

Vectors are useful data structures that act like dynamic one-dimensional arrays.

The clear() function is defined in the <vector> library. It is used to delete all the elements in a vector. When the vector is empty, its size becomes zero.

Syntax

myVec.clear()

Parameters

This function takes no parameters.

Return value

The function returns nothing.

The changes are made directly to the vector.

Example

#include <iostream>
#include <vector> // first include <vector>
using namespace std;
int main()
{
  //declaration of int vector
  vector<int> vec = {1, 2, 3, 4, 5};
  
  // returns length of vector as unsigned int
  unsigned int vecSize = vec.size();
  cout << "Before using clear(), size of vector: " << vecSize << endl;
  // calling clear()
  vec.clear();
  // recalculate size of vector
  vecSize = vec.size();
  cout << "After using clear(), size of vector: " << vecSize << endl;
  cout << endl;
  return 0;
}

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