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C++ Vector Library - assign() Function
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
template <class InputIterator> void assign(InputIterator first, InputIterator last);
C++11
template <class InputIterator> wvoid assign (InputIterator first, InputIterator last);
Parameters
first − Input iterator to the initial position in range.
last − Input iterator to the final position in range.
Return value
None
Exceptions
This member function never throws exception. If value of (first, last) is not valid index then behavior is undefined.
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> v(5, 100); cout << "Initial vector contents" << endl; for (int i = 0; i < v.size(); ++i) cout << v[i] << endl; cout << endl; cout << "Modified vector contents" << endl; v.assign(v.begin(), v.begin() + 2); for (int i = 0; i < v.size(); ++i) cout << v[i] << endl; return 0; }
Let us compile and run the above program, this will produce the following result −
Initial vector contents 100 100 100 100 100 Modified vector contents 100 100
vector.htm
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