Should You Use `std::distance` or Iterator Subtraction for Indexed Iteration?

Benefits of std::distance Over Subtracting Iterators for Indexed Iteration

Consider the following scenario: iterating through a vector and needing the index of the current element pointed to by an iterator. Two common methods used for this purpose are:

1. it - vec.begin()
2. std::distance(vec.begin(), it)

While both approaches provide correct results, they differ in certain aspects.

Pros and Cons of it - vec.begin():

• May not compile if the vector is changed to a different container type (e.g., list).
• Assumes that iterators point to the same container.

Pros and Cons of std::distance(vec.begin(), it):

• Compiles regardless of the container type.
• Guarantees that iterators belong to the same container.

In scenarios where the vector is expected to remain unchanged during iteration, it - vec.begin() can be used for simplicity. However, if there is a possibility of the vector being modified, it is advisable to use std::distance(vec.begin(), it) to ensure correctness and avoid performance issues.

Note that it is a common name for a container iterator (e.g., std::container_type::iterator it;), and its usage should adhere to the guidelines provided.

The above is the detailed content of Should You Use `std::distance` or Iterator Subtraction for Indexed Iteration?. For more information, please follow other related articles on the PHP Chinese website!