Suggestions about Improving Efficiency (gcc)
During the migration of CorbaFreeDynaMIT, we have noticed that some previous code may more or less decrease the efficiency. We are not talking about the algorithm at this time, though it should be more critical and significant.
Anyway, here are a few "rules of thumb" to avoid defect.
- Remove unnecessary code from loop. For example, making a function call to check the size of a list during the loop can be taken out of the loop if the size is not going to change during the loop.
- Use header files properly.To minimize the time we have to wait on the compiler, it's good to only include the headers we really need. Many people simply include iostream when they don't need to -- and that can penalize the runtime as well. (http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#10)
- Use "\n" in output stream other than std::endl whenever possible. std::endl not only sends out a new line, but also flush the stream, sending out the output immediately, and the buffer is lost. The next time we add something to the stream, we have to re-allocate the buffer, which is time-consuming and ususally unnecessary.