const vs non-const version of begin( )

[subramanian100in]

Suppose I have

vector<intv;
vector<int>::co nst_iterator citer = v.begin( );

Here which version of begin( ) is called ? const or non-const
version ?

Kindly explain

Thanks
V.Subramanian

[Kai-Uwe Bux]

su************* *@yahoo.com, India wrote:

Suppose I have

vector<intv;
vector<int>::co nst_iterator citer = v.begin( );

Here which version of begin( ) is called ? const or non-const
version ?

Should be non-const ...

Kindly explain

.... because v is not const.
Best

Kai-Uwe Bux

[=?UTF-8?B?RXJpayBXaWtzdHLDtm0=?=]

On 2007-10-25 09:59, su************* *@yahoo.com, India wrote:

Suppose I have

vector<intv;
vector<int>::co nst_iterator citer = v.begin( );

Here which version of begin( ) is called ? const or non-const
version ?

The non-const version. The reason for this is the fact that v is not
const. Consider the following example:

#include <vector>

void foo(const std::vector<int >& v)
{
std::vector<int >::const_iterat or it = v.begin();
}

int main()
{
std::vector<int v;
std::vector<int >::iterator it = v.begin();
std::vector<int >::const_iterat or cit = v.begin();

foo(v);
}

In foo() you must use a const_iterator since v is const, in main()
however you can use either since a const_iterator can be constructed
from an iterator. Notice though that I have not found anything in the
standard requiring this, so it might not be portable.

--
Erik Wikström

[Pete Becker]

On 2007-10-25 03:59:36 -0400, "su************ **@yahoo.com, India"
<su************ **@yahoo.comsai d:

Suppose I have

vector<intv;
vector<int>::co nst_iterator citer = v.begin( );

Here which version of begin( ) is called ? const or non-const
version ?

As everyone else has said, non-const. If that's a problem, there are
two ways to call the const version.

((const vector<int>&)v) .begin();
v.cbegin();

The latter is a recent addition to the C++0x specification, so chances
are your library doesn't have it.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)