Why is this an issue?
iostream.h header was provided with the first C++ compiler, CFront, and became the de facto standard. During the formal
standardization process of C++, many shortcomings in
iostream.h were fixed, but at the cost of introducing incompatibilities. Therefore,
it was decided not to change the existing
iostream.h and introduce the standard version as a new
Modern compilers tend to remove the support of the legacy
iostream.h header, and migrating to the standard version is encouraged.
This rule applies not only to
iostream, but to all standard C++ headers.
Noncompliant code example
#include <iostream.h> // Noncompliant
#include <fstream.h> // Noncompliant