Humans are also regularly harmed by pollution. Long-term exposure to air pollution, for example, can lead to chronic respiratory disease, lung cancer and other diseases. Toxic chemicals that accumulate in top predators can make some species unsafe to eat.
#include <iostream> is the Standard C++ way to include header files, the. 'iostream' is an identifier that maps to the file iostream.h. In older C++ you had to specify the filename of the header file, hence #include. <iostream.h>. Older compilers may not recognise the modern method, newer.
The ostream class is the primary class used when dealing with output streams. With output streams, the insertion operator (<<) is used to put values in the stream. This also makes sense: you insert your values into the stream, and the data consumer (eg. monitor) uses them.