Re: Accessing key and value from an Iterator

From:

Fei Liu <feiliu@aepnetworks.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 18 May 2007 13:59:34 -0400

Message-ID:

<f2kphi$h0c$1@aioe.org>

Josef Meile wrote:

Hi,

I have a Map of records and I know how to iterate over it and get the
records stored on it. ie:

struct featureRecord
{
    featureRecord(CAMERA_FEATURE fId = FEATURE_INVALID_FEATURE,
                             int val = -1) : featureId(fId), value(val)
{};
        //CAMERA_FEATURE is an enum defined in a third party library
    CAMERA_FEATURE featureId;
    int value;
};

map <string, featureRecord> _features;
_features["brightness"] = featureRecord(FEATURE_BRIGHTNESS);
_features["exposure"] = featureRecord(FEATURE_AUTO_EXPOSURE);
_features["focus"] = featureRecord(FEATURE_FOCUS);

map <string, featureRecord>::iterator iter = _features.begin();
while (iter != _features.end())
{
    featureRecord rec = iter->second;
    printf("feature id: %d",rec.featureId);
        ++iter;
}

Is there any way of getting the key as well? ie: printing something
like:

Feature brightness, id: 0
Feature exposure, id: 1
Feature focus, id: 2

I found that qt has an special Map iterator that does this:
* Qt 4's New Style of Iterators -> The Qt 4 Alternative: Java-Style
Iterators
  http://doc.trolltech.com/qq/qq12-qt4-iterators.html

Where you have an iterator that has a value() and key() method, but I
don't want to
use qt since it seems to be a big library.

Regards
Josef

For STL map, iter->first points to the key and iter->second points to
the value.