1, C++ is case sensitive, that is, it distinguishes between uppercase and lowercase characters.
C++ can use printf(), scanf(), and all other standard C input tools and output functions, only the regular stdio.h header file needs to be included.
The main() function can return an integer value to the function that calls it, and does not get any information from the function that calls it. In C++, main() is equivalent to main(void)
The input and output functions cin and cout functions are in the header file <iostream >. In the new style of C++, there is no extension .h after the header file. Such header files can include the namespace. If you use iostream instead of iostream.h, you should use namespace compilation instructions: using namespace std;classes, functions, and variables are the standard components of the C++ compiler, and they are now placed in the namespace std. This means: the cout function defined in iostream is actually: std::cout; endl is actually: std::endl; therefore, there can be:std::cout << "Hello, world.";