Is `std::copy()` or `std::memcpy()` Faster for Data Copying in C ?

Is std::copy() or std::memcpy() Faster for Data Copying?

When faced with the task of copying data in C , it's common to choose between std::copy() and std::memcpy(). While both functions perform data copying, they have different characteristics that can impact performance.

Traditionally, std::memcpy() was considered faster due to its direct and efficient memory copying mechanism. However, recent testing has revealed that std::copy() can provide a performance advantage.

Std::copy() vs. Std::memcpy() Performance Comparison

In a series of experiments, it was observed that std::copy() outperformed std::memcpy() in two different scenarios:

1. SHA-2 Hashing: Std::copy() showed a 2.99% performance improvement over std::memcpy() in a SHA-2 hashing implementation.
2. MD5 Hashing with Link Time Optimization: With link time optimization enabled, std::copy() exhibited a 0.72% performance improvement over std::memcpy() in a MD5 hashing implementation.

Explanation of Performance Differences

While std::memcpy() directly copies memory, std::copy() retains information about the data types involved. This allows compilers to optimize code based on the types and memory layout. Additionally, std::copy() supports aligned memory copying, which can further enhance performance.

When to Use Std::copy() or Std::memcpy()

Based on the performance comparison, it's generally recommended to use std::copy() unless there's a specific reason to use std::memcpy(). Std::copy() is more versatile, supports overlap in one direction, and provides comparable or better performance in a wide range of use cases.

Avoid Premature Optimization

It's important to note that these performance differences are often negligible and depend on specific implementation details. Premature optimization should be avoided, and it's crucial to focus on readable and maintainable code initially. In cases where performance is critical, experimentation and benchmarking should be performed to determine the best approach for a specific scenario.

The above is the detailed content of Is `std::copy()` or `std::memcpy()` Faster for Data Copying in C ?. For more information, please follow other related articles on the PHP Chinese website!