Iterating through a map.

foo.cpp

#include <map>
#include <iostream>
#include <string>
using namespace std;

int main() {
    // A map
    map<string, int> a_map;

    // Put some things in it.
    a_map["foo"] = 42;
    a_map["baz"] = -1;
    a_map["quux"] = 79;

    // Iterator over it
    for (map<string, int>::const_iterator i = a_map.begin(); // initial state of loop
         i != a_map.end(); // check for end of loop
         ++i) // advance
    {
        cout << "found an entry:" << endl;

        // I think i->first and i->second are equivalent to (*i).first and
        // (*i).second ... Perhaps there was a reason not to do that a long
        // time ago, or perhaps my brain is just old.
        cout << "  key: " << (*i).first << endl;
        cout << "  value: " << (*i).second << endl;
    }

    return 0;
}

// Line 16 looks better depending on how modern your C++ compiler is.  With C++11, it could be
// for (auto i = a_map.begin(); ...
//
// With GNU C++ before C++11, you could do this:
//
// for (typedecl(a.map.begin()) i = a_map.begin(); ...