There are two ways to convert any fundamental data to string.
- std::to_string
- std::ostringstream
- boost::lexical_cast
In this post, I will analyze which one is the fastest to convert any fundamental data to string. I am using google benchmark to measure the time difference. In all charts, y-axis is time in nano seconds and x-axis is both real time and cpu time.
- type=int input_count = 1
For only, one conversion, both std::stringstream and std::ostringstream take nearly same time. boost::lexical_cast in the fastest. And std::to_string is in between.
2. type=int input_count > 30
Here both std::stringstream and std::ostringstream outperform std::to_string and boost::lexical_cast. You can get better result by reusing std::stringstream and std::ostringstream buffer.
```cpp
std::ostringstream oss;
oss.str(“”);
oss.clear();
```
Creating stream objects are very expensive. So, reuse of buffer gives better result.
3. type=double input_count=1
Performance is very similar to integer. Boost lexical_cast outperforms everyone.
3. type=double input_count=30
For multiple inputs, boost::lexical_cast outperforms everyone else.
So, my observations are
- Always use std::to_string to convert any single value to std::string.
- In case of double, use std::string. If you need, precision, use std::ostringstream.
- In all other cases, use std::ostringstream.
- Prefer boost::lexical_cast if you have boost in your project
Image produced: https://github.com/asit-dhal/BenchmarkViewer