What’s an object file in C?

by

An object file is the real output from the compilation phase. It’s mostly machine code, but has info that allows a linker to see what symbols are in it as well as symbols it requires in order to work. (For reference, “symbols” are basically names of global objects, functions, etc.)

A linker takes all these object files and combines them to form one executable (assuming that it can, ie: that there aren’t any duplicate or undefined symbols). A lot of compilers will do this for you (read: they run the linker on their own) if you don’t tell them to “just compile” using command-line options. (-c is a common “just compile; don’t link” option.)

More Related Contents:

  1. Linker errors when compiling against glib…?
  2. Undefined reference to `initscr’ Ncurses
  3. Compiling multiple C files in a program
  4. How do I make this Linux program compile? [closed]
  5. Why do you have to link the math library in C?
  6. Why does the order of ‘-l’ option in gcc matter? [duplicate]
  7. Override a function call in C
  8. Is there a way to use gcc to convert C to MIPS?
  9. Can the linker inline functions?
  10. How to link multiple implementation files in C
  11. How to make weak linking work with GCC?
  12. When / How does Linux load shared libraries into address space?
  13. Undefined reference error for template method [duplicate]
  14. shared global variables in C
  15. Is a Linux executable “compatible” with OS X?
  16. What is -ffreestanding option in gcc?
  17. Why do you have to link the math library in C?
  18. Linking a C program directly with ld fails with undefined reference to `__libc_csu_fini`
  19. What is the reason function names are prefixed with an underscore by the compiler?
  20. .bss vs COMMON: what goes where?
  21. Undefined reference to `stdscr’ while using ncurses
  22. What is the use of .exp and what is the difference between .lib and .dll?
  23. How do I link object files in C? Fails with “Undefined symbols for architecture x86_64”
  24. Should variable definition be in header files?
  25. ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long unsigned int’ [-Wformat=] [duplicate]
  26. c math linker problems on Ubuntu 11.10 [duplicate]
  27. how do compilers assign memory addresses to variables?
  28. library not found for -lrt with QtCreator [mac os]
  29. Is accessing the “value” of a linker script variable undefined behavior in C?
  30. Query on -ffunction-section & -fdata-sections options of gcc

Leave a Comment