scanf() vs. cin: Which is Faster for C Input?

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:

Method	Execution Time
scanf()	6.4 seconds
cin and cout	24.3 seconds

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:

Method	Execution Time
cin and cout (with sync_with_stdio(false))	5.5 seconds

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.

The above is the detailed content of scanf() vs. cin: Which is Faster for C Input?. For more information, please follow other related articles on the PHP Chinese website!