Speed Comparison: scanf() vs. cin

Question:

Is it true that using scanf() in C programs is faster than using cin?

Answer:

Yes, scanf() is indeed faster than cin in C , as demonstrated by benchmarking results.

To conduct the test, a simple program was written to read a large list of numbers and calculate their XOR value. The program was implemented with both stdio's scanf() and iostream's cin and cout.

Results:

This significant speed difference is primarily attributed to the iostream functions' overhead in maintaining synchronization with C's stdio functions.

Optimizing cin's Performance:

However, by disabling the synchronization with std::ios::sync_with_stdio(false), the iostream version can achieve comparable performance:

With this optimization, iostream outperforms scanf() and becomes the fastest method.

Conclusion:

While scanf() is inherently faster than cin, its use in C programs is generally not recommended because:

• It is not type-safe, unlike cin.
• It leads to inconsistency in programming style, mixing C-style and C -style code.
• iostream provides a more modern and efficient way for input and output operations, especially when optimized by disabling synchronization.