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vector::begin

Returns a random-access iterator to the first element in the vector.

const_iterator begin() const;
iterator begin();

A random-access iterator addressing the first element in the vector or to the location succeeding an empty vector. You should always compare the value returned with vector::end to ensure it is valid.

If the return value of begin is assigned to a vector::const_iterator, the vector object cannot be modified. If the return value of begin is assigned to an vector::iterator, the vector object can be modified.

// vector_begin.cpp
// compile with: /EHsc
#include <vector>
#include <iostream>

int main()
{
    using namespace std;
    vector<int> c1;
    vector<int>::iterator c1_Iter;
    vector<int>::const_iterator c1_cIter;

    c1.push_back(1);
    c1.push_back(2);

    cout << "The vector c1 contains elements:";
    c1_Iter = c1.begin();
    for (; c1_Iter != c1.end(); c1_Iter++)
    {
        cout << " " << *c1_Iter;
    }
    cout << endl;

    cout << "The vector c1 now contains elements:";
    c1_Iter = c1.begin();
    *c1_Iter = 20;
    for (; c1_Iter != c1.end(); c1_Iter++)
    {
        cout << " " << *c1_Iter;
    }
    cout << endl;

    // The following line would be an error because iterator is const
    // *c1_cIter = 200;
}
The vector c1 contains elements: 1 2
The vector c1 now contains elements: 20 2

Header: <vector>

Namespace: std

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