How to Successfully Call C Functions from C Code?

How to Invoke C Functions from C Code

Calling C functions from C can be challenging, particularly if the "extern "C" void foo()" approach fails in the g compilation environment. To address this issue, consider the following alternative:

Compilation and Linking

First, compile the C code using:

gcc -c -o somecode.o somecode.c

Next, compile the C code using:

g++ -c -o othercode.o othercode.cpp

Finally, link the two files together using the C linker:

g++ -o yourprogram somecode.o othercode.o

Header Declaration

In the C code, include the header where the C function is declared. However, to ensure the C compiler recognizes the header as a C header, use the following syntax:

extern "C" {
#include "somecode.h"
}

somecode.h

The somecode.h header should declare the C function, similar to the following:

#ifndef SOMECODE_H_
#define SOMECODE_H_

void foo();

#endif

Additional Notes

• The principle of separate compilation and linking remains the same regardless of the compiler used (e.g., gcc, clang).
• This approach allows for the coexistence of C and C code within a single project.

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