Question

This is my code:

// Start performance test clock
assert((start=clock())!=-1);

// Some reading and writing methods

// Get stop time
stop = clock();

cout << stop << endl;

// Calculate operation time
double result = (double)(stop-start)/CLOCKS_PER_SEC;

// Print result
cout << "--> Finished analysing in " << result << "s" << endl;

It works great when I debug my program, but when I run the release version,
stop receives a much smaller value than start, and result is a negative number.

Any ideas?

Answer 1

The assignment of start should not be in the assert statement. assert is typically a no-op in release builds. So in the debug build, the statement start=clock() would be executed, but in the release build, it would not. So it is possible (depending on earlier code and the declaration of start) that it is not initialized. It is typically desirable to avoid using assert statements that have side effects; it can lead to subtle differences/bugs between debug and release builds.

It might be better to write it like this:

start = clock();
assert(start != -1);