C++ Vector Library - assign() Function

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Description

The C++ function std::vector::assign() assign new values to the vector elements by replacing old ones. It modifies size of vector if necessary.

If memory allocation happens allocation is allocated by internal allocator.

Declaration

Following is the declaration for std::vector::assign() function form std::vector header.

C++98

void assign (size_type n, const value_type& val);

C++11

void assign (size_type n, const value_type& val);

Parameters

• n − Size of vector.

• val − Value for each element.

Return value

None

Exceptions

This member function never throws exception.

Time complexity

Linear i.e. O(n)

Example

The following example shows the usage of std::vector::assign() function.

#include <iostream>
#include <vector>

using namespace std;

int main(void) {
   vector<int> v1;

   cout << "Initial size  = " << v1.size() << endl;

   /* 5 integers with value = 100 */
   v1.assign(5, 100);

   cout << "Modified size = " << v1.size() << endl;

   /* display vector values */
   for (int i = 0; i < v1.size(); ++i)
      cout << v1[i] << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Initial size  = 0
Modified size = 5
100
100
100
100
100