extern “C” makes names not mangled. It used when: We need to use some C library in C++ extern “C” int foo(int); We need export some C++ code to C extern “C” int foo(int) { something; } We need an ability to resolve symbol in shared library — so we need to get rid mangling … Read more
extern “C” is used to ensure that the symbols following are not mangled (decorated). Example: Let’s say we have the following code in a file called test.cpp: extern “C” { int foo() { return 1; } } int bar() { return 1; } If you run gcc -c test.cpp -o test.o Take a look at … Read more
You need to use extern “C” in C++ when declaring a function that was implemented/compiled in C. The use of extern “C” tells the compiler/linker to use the C naming and calling conventions, instead of the C++ name mangling and C++ calling conventions that would be used otherwise. For functions provided by other libraries, you … Read more
Yes, you are just lucky 🙂 The extern “C” is one language linkage for the C language that every C++ compiler has to support, beside extern “C++” which is the default. Compilers may supports other language linkages. GCC for example supports extern “Java” which allows interfacing with java code (though that’s quite cumbersome). extern “C” … Read more
Compile the C code like this: gcc -c -o somecode.o somecode.c Then the C++ code like this: g++ -c -o othercode.o othercode.cpp Then link them together, with the C++ linker: g++ -o yourprogram somecode.o othercode.o You also have to tell the C++ compiler a C header is coming when you include the declaration for the … Read more
C and C++ are superficially similar, but each compiles into a very different set of code. When you include a header file with a C++ compiler, the compiler is expecting C++ code. If, however, it is a C header, then the compiler expects the data contained in the header file to be compiled to a … Read more
extern “C” doesn’t really change the way that the compiler reads the code. If your code is in a .c file, it will be compiled as C, if it is in a .cpp file, it will be compiled as C++ (unless you do something strange to your configuration). What extern “C” does is affect linkage. … Read more
You need to create a C API for exposing the functionality of your C++ code. Basically, you will need to write C++ code that is declared extern “C” and that has a pure C API (not using classes, for example) that wraps the C++ library. Then you use the pure C wrapper library that you’ve … Read more
extern “C” makes a function-name in C++ have C linkage (compiler does not mangle the name) so that client C code can link to (use) your function using a C compatible header file that contains just the declaration of your function. Your function definition is contained in a binary format (that was compiled by your … Read more