Does std::map Guarantee Ordered Iteration?

Order of Iteration in Std::map

In the context of C , the std::map data structure provides a mapping between keys and corresponding values. A crucial characteristic of std::map is that it maintains a sorted order of its elements based on the keys.

The question arises: does the standard guarantee the order of iteration through a std::map? The answer to this question is a resounding yes. The standard dictates that iterating through the elements of a std::map from std::map::begin() to std::map::end() will result in the iteration of elements in ascending order according to the keys.

For instance, consider a std::map named map_. Suppose we insert elements with keys 1, 2, and 3 into the map. Iterating over the map using a for loop will print the values 2, 3, and 4, corresponding to keys 1, 2, and 3, respectively. This order is guaranteed by the standard.

The sorting order is not an arbitrary feature but rather an intrinsic aspect of the std::map data structure. This ordering enables efficient operations such as binary search, resulting in logarithmic complexity in the number of elements.

Additional Features:

• *begin() provides the element with the smallest key.
• *rbegin() provides the element with the largest key.
• Equality of key values is determined by the expression !compare(a,b) && !compare(b,a), where compare is the comparison operator.

The above is the detailed content of Does std::map Guarantee Ordered Iteration?. For more information, please follow other related articles on the PHP Chinese website!