Re: Query regarding iterators and vector
Jerry Coffin <jcoffin@taeus.com> wrote:
prasadmpatil@gmail.com says...
I am new STL programming.
I have a query regarding vectors. If I am iterating over a vector
using a iterator, but do some operations that modify the size of the
vector. Will the iterator recognize this?
I wrote the following program to test this out.
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main()
{
vector<int> a;
a.push_back(1);
a.push_back(2);
a.push_back(3);
cout<<"Vector test begin"<<endl;
vector<int>::iterator iter0;
for(iter0=a.begin(); iter0!=a.end(); iter0++)
{
cout << "\n value: " << (*iter0)<<endl;
if(*iter0 == 2)
{
a.push_back(4);
a.push_back(5);
}
}
cout<<"Vector test end";
}
A push_back on a vector invalidates all iterators into that vector.
Not quite true. push_back only invalidates the iterators if size() <
capacity() before the push_back occurs. If the OP had done a reserve(5)
before entering the loop, all would have been well.
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