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This is the answer of exercise #7: AddOne.
Question #0: How many correct ways are there to do this?
The answer is a product of the number of ways to add one to an int and the number of ways to iterate through a std::vector.
The number of ways to add one to an int are five:
- Assignment 1st (x=1+x)
- Assignment 2nd (x=x+1)
- Increase (x+=1)
- Post-increment (x++)
- Pre-increment (++x)
The number of ways to iterate through a std::vector are twelve:
Using a for-loop, requesting the std::vector its size only once- Using a for-loop, requesting the std::vector its size every iteration
- Using an iterator, requesting the std::vector its end only once
- Using an iterator, requesting the std::vector its end only every iteration
- Using an algorithm to a non-inlined function
- Using an algorithm to an inlined function
- Using an algorithm to a functor with a non-inlined operator()
- Using an algorithm to a functor with an inlined operator()
Using BOOST_FOREACH- Using the Boost Lambda library
Using the C++11 its ranged for-loop- Using the C++11 lambda expressions
This makes the number of ways to do this sixty!
There are two more:
- Using an algorithm to std::plus using std::bind1st
- Using an algorithm to std::plus using std::bind2nd
Total: there are sixty-two ways to add one to each element in a std::vector!
P.S. an additional way (though beyond this exercise) is to use assembler.
Question #1: Write a program that tests which way is fastest
This kind of program is called a benchmark.
There are too many ways to write one, so I'll just show you mine:
In the zip file, the results of the profilers gprof and
cachegrind are included as text files.
Go back to Richel Bilderbeek's C++ page.
Go back to Richel Bilderbeek's homepage.
