The difference between include <iostream> and include <iostream.h> in C + +---->

To put it simply:. h is the header file for standard C, and No. h is the standard C + + header file, both of which are header files. The reason for the difference between these two forms is that the development history of C + + is decided, just right there are other people also ask this question, here I answer again (note that vs2008 and VS2005 support for standard C + + is the same):

1, take iostream and stdio.h for example, iostream is the library of C + +, stdio.h is the library of standard C.

2. The new C + + standard rejects the. h header file, so there is no iostream.h header file in the vs2005.

3, in the early VS version, such as VC6.0, with the old version of the C + + standard library, such as iostream.h, and then the standard library did not introduce namespaces. So the direct # include <iostream.h> is possible. But in vs2005, the new C + + standard library was used, with # include <iostream> only.

4. Namespaces can contain many things, such as function names, identifiers, data types, and so on. The new C + + standard puts the names in the standard library in the Std namespace, so after # include <iostream>, you must use the namespace STD of the standard library to use the classes and functions in the standard library, which is the using namespace std ;

5, for the standard library of C, for example, stdio.h, there is no concept of namespaces, so directly included can be used.

6, the new C + + standard library in order to unify the previous C standard library, the original C standard library has also been put into the Std namespace, and the original C standard library removed. h suffix, preceded by the letter "C", for example stdio.h becomes Cstdio, when used for # include < Cstdio>, whose contents are the same as # include <stdio.h>, but have to use the namespace STD, which is the using namespace std;

7, therefore, for the new C + + standard library, there is no. h header file, such as iostream, after the header file is included, you must use the STD namespace to use the contents of the library. For the C standard library, there are two methods of use, one is the old. h form, such as stdio.h directly containing it, and the other is in C + + unified form, such as Cstdio, and the C + + standard library, including the subsequent addition of using the namespace STD, can be used. It is recommended to use the following unified form, such as you want to both C and C + + libraries, you can write: #include <cstdio> #include <iostream>using namespace std;

The difference between include <iostream> and include <iostream.h> in C + +---->