=====begin=====
Syntax:

<code>
    #include <map>
    iterator begin();
    const_iterator begin() const;
</code>

The begin() function returns an iterator to the first element of the map. If the map doesn't contain any element, then begin() returns the same as [[end]]().

begin() should run in [[/complexity|constant time]].

For example, the following code uses begin() to initialize an iterator that is used to traverse a list:

<code>
    map<string,int> stringCounts;
    string str;

    while( cin >> str ) ++stringCounts[str];

    map<string,int>::iterator iter;
    for( iter = stringCounts.begin(); iter != stringCounts.end(); ++iter ) {
      cout << "word: " << iter->first << ", count: " << iter->second << endl;
    }
</code>

When given this input:

<code terminal>
    here are some words and here are some more words
</code>

...the above code generates this output:

<code terminal>
    word: and, count: 1
    word: are, count: 2
    word: here, count: 2
    word: more, count: 1
    word: some, count: 2
    word: words, count: 2
</code>


Related Topics: [[end]], [[rbegin]], [[rend]]