Measure execution time of a function in C++
We can find out the time taken by different parts of a program by using the std::chrono library introduced in C++ 11. We have discussed at How to measure time taken by a program in C. The functions described there are supported in C++ too but they are C specific. For clean and robust C++ programs we should strive to use C++ specific language constructs only.
std::chrono has two distinct objects–timepoint and duration. A timepoint as the name suggests represents a point in time whereas a duration represents an interval or span of time. The C++ library allows us to subtract two timepoints to get the interval of time passed in between. Using provided methods we can also convert this duration to appropriate units.
The std::chrono provides us with three clocks with varying accuracy. The high_resolution_clock is the most accurate and hence it is used to measure execution time.
Step 1: Get the timepoint before the function is called
Step 2: Get the timepoint after the function is called
Step 3: Get the difference in timepoints and cast it to required units
A complete C++ program demonstrating the procedure is given below. We fill up a vector with some random numbers and measure the time taken by sort() function to sort this vector.
Output: (Machine Dependent)
Time taken by function: 3062 microseconds