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
“Can C++ functions marked as Extern “C” throw?” Yes, in the sense that neither the language nor the compiler will prevent you from doing so. No, in the sense that if you throw, it would be an undefined behaviour, as the C++ exception crosses language boundaries. In practice: do not do it. Catch the exception … 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
Language linkage is the term used for linkage between C++ and non-C++ code fragments. Typically, in a C++ program, all function names, function types and even variable names have the default C++ language linkage. A C++ object code can be linked to another object code which is produced using some other source language (like C) … Read more
The ‘extern “C”‘ should not be required on the function defintion as long as the declaration has it and is already seen in the compilation of the definition. The standard specifically states (7.5/5 Linkage specifications): A function can be declared without a linkage specification after an explicit linkage specification has been seen; the linkage explicitly … 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
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
It was sort of answered above, but I’ll try to put things into context. First, C came first. As such, what C does is, sort of, the “default”. It does not mangle names because it just doesn’t. A function name is a function name. A global is a global, and so on. Then C++ came … 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