Ch (computer programming)

Ch (/ˌsiːˈeɪtʃ/) is a cross-platform C and C++ interpreter originally designed by Dr. Harry H. Cheng as a scripting language for beginners to learn math, computing, numerics, and programming in C/C++.

Now developed by SoftIntegration, Inc., Ch is written in C and runs under Windows, Linux, Mac OS X, FreeBSD, AIX, Solaris, QNX and HP-UX. It supports C90 and major C99 features, but it does not support the full set of C++ features. C99 complex number, IEEE-754 floating-point arithmetic, VLA features were supported in Ch before they became part of the C99 standard .

Ch is now used and integrated into curriculum by many universities and schools for learning computing and programming in C/C++ . Ch can also be run as an interactive shell to execute C statement, C script file, Unix commands, and Windows commands (under windows only).

Features

C/C++ interpreter

Ch supports the 1999 ISO C Standard (C99) and C++ classes. It is a superset of C with C++ classes. C99 major features such as complex numbers, variable length arrays (VLAs), IEEE-754 floating-point arithmetic and generic mathematical functions are supported. Wide characters in Addendum 1 for C90 is also supported.

The following C++ features are available in Ch:

• Member function
• Mixed code and declaration
• The this-> pointer
• Reference type and pass-by-reference
• Function-style type conversion
• Class
• private/public data and functions in class. Ch is compatible with C++ that by default, members of a class definition are assumed to be private until a 'public' declaration is given
• Static member of class/struct/union
• Const member functions
• The new and delete operators
• Constructors and destructors
• Polymorphic functions
• The scope resolution operator ::
• The I/O cout, cerr, cin with endl
• Arguments for variadic functions are optional

Ch supports classes in C++ with the following additional capabilities:

• Classes inside member functions
• Nested functions with classes
• Pass member function to argument of pointer-to-function type of functions

Embeddable scripting

Ch can interface with existing C/C++ libraries and call C/C++ functions from Ch script. As a C/C++ interpreter, Ch can be used as a scripting engine for your applications. The pointer to array or variables can be passed and shared in both binary C space and ch scripting space. It extends your applications with a C compatible scripting language. One of the embedded ch scripting application is Mobile-C. Mobile-C has been used for collaborative visualization of distributed mesh model.

Shell programming and cross-platform scripting

Ch is a C-compatible shell similar to C-shell (csh). It can be used as login shell. Ch has a built-in string type (string_t) for automatic memory allocation and de-allocation. It makes C/C++ easy of scripting. It supports shell alias, history, filename wildcarding, piping and iteration etc.

2D/3D plotting and numerical computing

Ch has built-in 2D/3D graphical plotting features and computational arrays for numerical computing. A 2D linear equation of the form b = A*x can be written verbatim in Ch.

Examples

"Hello, world!" in Ch

There are two ways to run Ch code. One is:

   printf("Hello world!\n");

Another is:

   #include <stdio.h>
   int main() {
       printf("Hello world!\n");
   }

Ch also supports interactive shell command and C statements.

 > int i, *p, **p2     // i is an integer, p pointer, p2 double pointer
 > i=10                // i is assigned value 10
   10
 > p=&i                // p points to address of i
   00D847C0
 > *p                  // the memory pointed by p has value 10
   10
 > p2=&p               // p2 points to address of p
   00D84D30
 > **p2                // the memory pointed by the pointer at p2 has value 10
   10
 >

Numerical computing in Ch

   #include <stdio.h>
   #include <array.h>
   int main() {
       array double A[2][3] = {1, 2, 3,
                           4, 5, 6};
       array double B[3][2];
       printf("A= \n%f \n", A+A);
       B = 2*transpose(A);
       printf("B= \n%f \n", B);
   }

The output is:

   A=
   2.000000 4.000000 6.000000
   8.000000 10.000000 12.000000
   B=
   2.000000 8.000000
   4.000000 10.000000
   6.000000 12.000000

Shell programming

Find and compile all .c files into .o in the current directory for which the .o file is old or absent:

   #!/bin/ch
   #include <sys/stat.h>
   struct stat cstat, ostat;
   string_t c, o;
   foreach (c; `find . -name "*.c"`)
   {
       o=`echo $c | sed 's/.c$/.o/'`;
       stat(o, &ostat); stat(c, &cstat);
       if (ostat.st_mtime > cstat.st_mtime)
       {
           echo "compiling $c to $o";
           gcc -c -o "$o" "$c";
       }
   }

2D/3D plotting in Ch

To plot a sine wave:

  #include <math.h>
  #include <chplot.h>
  int main() {
       int numpoints = 36;
       array double x[numpoints], y[numpoints];
       linspace(x, 0, 360); // assign x with values from 0 to 360 linearly
       y = sin(x*M_PI/180);
       plotxy(x, y, "Ch plot", "xlabel", "ylabel");
   }

See also

• CINT
• Pike (programming language)

Further reading

• Heller, Martin (2001). "The Ch Language Environment". Byte Magazine. {{cite journal}}: Cite journal requires |journal= (help)
• Cheng, Harry (2002). "C99 & Numeric Computing". Dr. Dobb's Journal: 28–34. {{cite journal}}: Cite journal requires |journal= (help)
• Cheng, Harry (2006). "Ch: A C/C++ Interpreter for Script Computing". Dr. Dobb's Journal: 6–12. {{cite journal}}: Cite journal requires |journal= (help)
• Cheng, Harry (2009). C For Engineers & Scientists, An Interpretive Approach. McGraw-Hill. ISBN 978-0077290467.

External links

• SoftIntegration Home Page
• Mobile-C: a Multi-Agent Platform for Mobile C/C++ Agents Home Page
• C99 features in Ch
• Ch Shell
• SQLite in Ch
• Perl Compatible Reg. Expressions in Ch
• ChScite
• Ch Mini-XML
• GNU Scientific Library in Ch
• Ch libxml2 package
• ChOpenAL