The preprocessor #include directive has the form #include <FILENAME>, where FILENAME is a string for the included header file.

Standard C library headers can be included in C++ source files exactly as in C source files. For example, both C and C++ source files can make references to functions printf, scanf, fprintf, and others by including header file <stdio.h>.

C++ also allows standard C library functions to be referenced using names qualified by namespace std. However, in that case, standard C library header filenames must be transformed by the following rule:

1. the header file name no longer maintains the .h extension, and
2. the header file name has to be preceded by character c.

For example, header file ctype.h becomes cctype.

Apply this rule to the following standard C library header filenames to match their corresponding C++ header file [so that functions declared in these standard C library headers can only be referenced in C++ code by qualifying their names with namespace std].