C To C++ Converter


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This documentation is for: ctocpp, version 1.2.0
Mail: webmaster@scriptol.com.
Home page: http://www.scriptol.com/
Alternate page: http://scriptol.tuxfamily.org/


Node:Overview, Next:, Previous:Top, Up:Top

Overview

These scripts allow to convert a C file or a whole C project to C++. I have written it because I have not found a such tool over the Net. Since I have written the project before Scriptol was available, it is written in Python and you need to install the Python interpreter to run the scripts. These are simple scripts, anyway. They require C sources written with a clear programming style: one statement per line is required in most case. Programs are available over the web to format properly C sources.
Before to start, you need to mark as "static", any variable or function you want not being converted to class members.

The scripts build classes, and global variables will become members of the classes, functions will become methods.

The command to run the program is:
python ctocpp.py ... some arguments ...
but in this manual, I simplify by:
ctocpp ... some arguments ...

Being an all static system at this stage, the new C++ program is not very different of the C one, apart to be more readable. But this is a basis to add new classes and methods or to integrate it in a larger C++ project.


Node:Requirements & conventions, Next:, Previous:Overview, Up:Top

Requirements & conventions

For Windows, Linux and others, as Python is universal.
Requires the python interpreter (www.python.org) installed.

To convert your C project into a C++ one, you need for:
- Some files with ".c" extensions.
- The python interpreter installed. (Get it at www.python.org)
- The files below, from the current archive:

wstring.py pattern.py mklist.py lexer.py mover.py
mkclass.py allhead.py iscomp.py mkcpp.py mkheader.py

Conventions:
- C sources must have the .c extension.
- C headers must have the .h extension.
- a variable with the "static" modifier remain global and doesn't become a class member (nothing to do with a C++ static member! class attributes are declared as static from variable not declared as static, because static for C++ class is a different thing).
- If a declaration is splitted, parts must be ended by a comma.
Example:
mydecl(int x,
int y);


Node:How it works, Next:, Previous:Requirements & conventions, Up:Top

How it works

The conversion process is accomplished in a single passe if no option is given, or in several steps according to the options:
1) Use -list to build the list of all sources automatically.
2) Use -include to complete the header files.
3) Use -class to create the C++ classes.
The name of a class is the name of the C file, all variables and functions will be declared static.
You can change manually the class produced into ".hpp" files.
4) Use -all to build the new list of header files. 5) Use -prop to produce ".cpp" files inside which all c functions are transformed into methods according to the class declaration.
Global variables are removed from the .cpp files.
References to variables and functions are replaced by to C++ equivalents references to attributes and methods.

You need also a makefile to build your C++ program. This depends the compiler you use and is not covered here.


Node:Other tools, Next:, Previous:How it works, Up:Top

Other tools

Some tools here included may be used for a general purpose, type the name of the tool without parameter to get the usage. The main ones are:
- mkhead.py
may be used as a standalone tool to make and update c header files. Required here for multi-lines declarations.
- search.py
is a general purpose search-replace tool to process strings or identifiers inside text files.
- mover.py
translates a project from a directory to another one. Changes #include statements.

Some .py files are modules called by the named scripts.


Node:Limitations, Next:, Previous:Other tools, Up:Top

Limitations


Node:General restrictions, Next:, Previous:Limitations, Up:Limitations

General restrictions

- The program assumes the C code is written with a good programming style. What is hard to read for an human will be hard to parse for the program too.

- Define statements used in code must be moved to header file, they are processed only in some cases by the scripts.

- The step -class is the more complex ones. If the conversion doesn't work, then perform it manually instead, it is also the less fastidious ones. The following -prop should work without problem, and luckily, what it does is also the more annoying part!


Node:Make list, Next:, Previous:General restrictions, Up:Limitations

Make list

Limitations for the -list command.

- If your project uses a list of files as the ones of Turbo C, you don't need for mklist.
The program is able to build this list providing that all functions have a prototype in header file and this header file is included in each source using the function. Otherwise you have to complete the list.
- The #include statements should use the "" enclosures for your header files and the <> ones, for external libraries.
For example: #include <stdlib.h>
#include "myheader.h"


Node:Make header, Next:, Previous:Make list, Up:Limitations

Make header

Limitations for the -include command.

- The script doesn't manage conditional compilation.
Statements as #if or #ifdef are not managed when building the header file.

- Functions may take macro arguments as the FILE one.
This can be a problem inside an header file. Such problem is already solved if each function has a prototype in the original source, but this is no always the case, as old compiler allows to omit them.
When such problems are encoutered in producing the header file, change manually the file.


Node:Make class, Next:, Previous:Make header, Up:Limitations

Make class

Limitations for the -class command.

- The name automatically choosen, that of the file, may conflict.
A function with the same name that the file will has same name that a class and will be considered as a constructor.


Node:Step by step, Next:, Previous:Make class, Up:Top

Step by step

If your source are are saved and if you are sure your code is compatible with C++ conventions that are more restrictive than C ones, but compatible with it, you can type a single command:

COMMAND: ctocpp mainfile.c projectlist

In other cases, process step by step as below...


Node:Moving the files, Next:, Previous:Step by step, Up:Step by step

Moving the files

Step 1: Move the files. This is optional.

COMMAND: mover mainfile.c olddir@newdir [olddir@newdir]

- mainfile.c is the file that holds the main() function.
- olddir is a directories where the files are stored.
- newdir is the new location.
- several old@new couples are required if the project stays inside several directories.
You can move all directories into a single one.
N.B.: If you move the files with a file manager, the #include statements will not be updated.


Node:Making a list, Next:, Previous:Moving the files, Up:Step by step

Making a list

Step 2: Make the project list with mklist.py

COMMAND: ctocpp -l mainfile.c prjlist

- mainfile.c is the file that holds the main() function.
- prjlist is the name of the file that will contains the list of all .c sources of the project (you choose a name for it).
It will be overwritten without prompting.


Node:Verify headers, Next:, Previous:Making a list, Up:Step by step

Verify headers

Step 3: Make declarations inside headers, matching the definitions inside sources.

C compiler are less restrictive than C++ one, a function can be used without prototypes.
To update your sources to C++ rules, use mkheader.py

COMMAND: ctocpp -i mainfile.c projectlist

- do not forget the @ before the project's filename.


Node:Generating classes, Next:, Previous:Verify headers, Up:Step by step

Generating classes

Step 4:
If you want to define you own classes, skip this step.
-class or mkclass allows to make a class from variables and prototypes from an header file. If produces a new .hpp file and doesn't change the previous header.

COMMAND: ctocpp -c mainfile.c projectlist

- Do not forget the symbol before the project's filename.
- If a function has name that is that of the file, it will be considered as a constructor. The class name must be changed.

When all C++ headers are created you may change the default classes names or move their members from class to class if you want.
If a method has the same name that the class, you must to rename the class, as the name is reserved to a constructor.


Node:List of headers, Next:, Previous:Generating classes, Up:Step by step

List of headers

Step 5:
Now you need the list of all header files.
This is not the same that the list of sources, as the project may use header to include with no corresponding source.

COMMAND: ctocpp -a mainfile.c projectlist

- Headlist if the name of the file to create, that will hold all header filenames. No symbol at this stage (It is used to differentiate a source from a list of files).
- The file is overwritten without prompting.


Node:Propagating changes, Next:, Previous:List of headers, Up:Step by step

Propagating changes

Step 6:
The last step produces a full set of C++ files with .cpp extensions, from .c and .hpp files.
- Function are transformed in methods.
- Global variables are made static and integrated into class declarations.
- Call of functions are replaced by call of methods.
- Global variables references are replaced by references to members.

COMMAND: ctocpp -c mainfile.c projectlist

- Prjlist is the name of the file that hold all .c sources in the project. The symbol prefixes the name.
- Headlist is a file that holds all .h headers. Symbol before it.


Node:Example, Next:, Previous:Propagating changes, Up:Top

Example

Now you are ready to compile your C++ project.

N.B.: When you use a sub-program directly, if you omit the "@" symbol in front of a filename when required, the script will process the file itself, not a list of files. This allows to convert a single file.

Example: CDList (available at http://scriptol.tuxfamily.org)

The / symbol is inverted for Windows.
The scripts are installed into the /ctocpp directory.
The CDList files are in the /cdwin directory.
The program use a personal GUI library, in the /gui directory.
The main function is inside the listit.c file.
I choose to move all necessary file into the /cdnew directory and give the new project file the "cdlist" name:

You can type simply: ctocpp \cdnew\listit.c \cdnew\cdlist But this is not recommend, as you may have to rename classes automatically created.
Or you can perform detailed steps:

From the /ctocpp directory, using the scripts directly:
Step 1: mover /cdwin/listit.c /gui:/cdnew /cdwin:/cdnew
Step 2: mklist /cdnew/listit.c /cdnew/cdlist.prj
Step 3: mkheader @/cdnew/cdlist.prj
Step 4: mkclass @/cdnew/cdlist.prj
Step 5: allhead /cdnew/listit.c /cdnew/cdlist.hpj
Step 6: mkcpp @/cdnew/cdlist.prj @/cdnew/cdlist.hpj

N.B.:
- the @ symbol is used when the file is a list of files and when it is read, not when it is created.

Delete the .c files and type: make -fcdcpp.mak
(makefile for Turbo C++)


Node:Index, Previous:Example, Up:Top

Index

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