Call C methods from C++/Java/C# code?

Question

Many of today's programming languages are based on C; like C++, C#, Java, Objective-C. So could I call a C method from C++ code? Or call C from Java or C#? Or is this goal out of reach and unreasonable? Please include a quick code sample for my and everyone else's understanding.

"…are based on C; like…C#, Java…" -- Are they? I think this is limited to curly braces and semicolons in those cases. — sellibitze, Jun 13 '10 at 08:22
agree, syntax resemblance does not mean they are based on C even if they could be (or could have been as C++); C has no methods. C++ and Objective-C can call C functions and link to C-written libraries without problems. — ShinTakezou, Jun 13 '10 at 09:48

score 5 · Accepted Answer · edited May 23 '17 at 11:48

5

C++,C#, Objective-C, and Java can all call C routines. Here are a few links that will give you an overview of the process needed to call C from each language you asked about.

edited May 23 '17 at 11:48

Community

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answered Jun 13 '10 at 07:50

Alan

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Can it call C routines from just compiled C code. Or does the C code have to be in a library? – Mohit Deshpande Jun 13 '10 at 07:52
C++ and Objective-C can compile C, as they are both supersets. C# and Java will require C code to exist in libs – Alan Jun 13 '10 at 07:55
the article about java is not about calling c from java but calling java from c – ManBugra Jun 13 '10 at 08:20

score 2 · Answer 2 · 2010-06-13T08:57:33.457

An example of calling C from C++. Save this C function in a file called a.c:

int f() {
   return 42;
}

and compile it:

gcc -c a.c

which will produce a file called a.o. Now write a C++ program in a file called main.cpp:

#include <iostream>
extern "C" int f();

int main() {
   std::cout << f() << std::endl;
}

and compile and link with:

g++ main.cpp a.o -o myprog

which will produce an execuatable called myprog which prints 42 when run.

score 1 · Answer 3 · answered Jun 13 '10 at 08:52

1

To Call C Methods In Java...

there a Keyword "native" in Which You can write machine-dependent C code and invoke it from Java....

Basically it creates a DLL file..then u have to load it in ur program...

a nice example here....

answered Jun 13 '10 at 08:52

vs4vijay

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score 0 · Answer 4 · answered Jul 29 '10 at 17:46

To call C methods from Java, there are multiple options, including:

JNA - Java Native Access. Free. Easy to use. Hand-declaration of Java classes and interfaces paralleling existing C structs and functions. Slower than JNI - by a few hundred nanoseconds per call.
JNI - Java Native Interface. Free. Fastest option. Requires a layer of native glue code between your Java code and the native functions you want to call.
JNIWrapper - Commercial product, similar to JNA.

score 0 · Answer 5 · answered Mar 02 '11 at 15:20

0

To call C/C++ from Java, also give a look at BridJ (it's like JNA with C++ and better performance).

answered Mar 02 '11 at 15:20

zOlive

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Call C methods from C++/Java/C# code?

5 Answers5