#3 When filling up or copying into a vector, prefer assignment over insert() or push_back(). If you’re interested, you can check C++ Coding Standards: 101 Rules, Guidelines, and Best Practices, item # 82 for details of the swap idiom. Helper function to populate the test vectorsĬout ( c ).swap( c ) // the shrink-to-fit idiom to shed excess capacityĬontainer().swap( c ) // the idiom to shed all contents and capacity Test struct to be inserted/removed from vector We’re using a TestStruct and a FillVector() method to populate the test vectors.
#Stl vector code code#
Feel free to download it for profiling vector performance on your system.The code snippets in the post will reflect just one iteration to keep things simple. We’ll be running each test 100 times and taking the average runtime for comparison purposes.The actual code used to run the test is available here. We’ll be using the Stopwatch made by Kjell available at. Infrastructure and methodology for the performance tests:Īll the tests are performed on my Surface Book having a core i7 Ghz processor, 8 GB RAM and VS2015 C++ Compiler running under Windows 10. We’ll look at both efficient and inefficient ways to perform the most common programming tasks using vectors, measure the performance gain we obtain by using vectors efficiently and try to understand why we’re getting the performance gain. In this article we’ll look at 6 ways to optimize usage of vectors. However, Vector is just a tool and like any tool, it can be used both effectively or ineffectively. For mere mortals like us, we take this as gospel and just run with it.
In the words of Bjarne Stroutsoup – “ By default, use Vector when you need a container”.
Vector is like the swiss army knife of C++ STL containers.
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