Mixed-Language Programming & External Linkage
By Giri Mandalika, December 01, 2005
Calling C code from C++ should be relatively straightforward, but understanding the concept of linkage is key to ensuring a smooth compile.
December, 2005: Mixed-Language Programming & External Linkage
Figure 2: Using elfdump to look at symbol tables.
%elfdump -s libgreet.so
Symbol Table Section: .symtab
index value size type bind oth ver shndx name
...
[1] 0x00000000 0x00000000 FILE LOCL D 0 ABS libgreet.so
...
[37] 0x00000268 0x00000004 OBJT GLOB D 0 .rodata _lib_version
[38] 0x000102f3 0x00000000 OBJT GLOB D 0 .data1 _edata
[39] 0x00000228 0x00000028 FUNC GLOB D 0 .text greet
[40] 0x0001026c 0x00000000 OBJT GLOB D 0 .dynamic _DYNAMIC
%elfdump -s mixedcode.o
Symbol Table Section: .symtab
index value size type bind oth ver shndx name
[0] 0x00000000 0x00000000 NOTY LOCL D 0 UNDEF
[1] 0x00000000 0x00000000 FILE LOCL D 0 ABS mixedcode.cpp
[2] 0x00000000 0x00000000 SECT LOCL D 0 .rodata
[3] 0x00000000 0x00000000 FUNC GLOB D 0 UNDEF
__1cDstd2l6Frn0ANbasic_ostream4Ccn0ALchar_traits4Cc____pkc_2_
[4] 0x00000000 0x00000000 FUNC GLOB D 0 UNDEF __1cFgreet6F_pc_
[5] 0x00000000 0x00000000 NOTY GLOB D 0 UNDEF __1cDstdEcout_
[6] 0x00000010 0x00000050 FUNC GLOB D 0 .text main
[7] 0x00000000 0x00000000 NOTY GLOB D 0 ABS __fsr_init_value
%dem __1cFgreet6F_pc_
__1cFgreet6F_pc_ == char*greet()
