When debugging or linking, what does the word "symbol" refer to?

Question

I am doing some work with gdb and have found references in the documentation to "symbols". Is this another word for externally (exported) visible variables ?

Thanks,

Scott

Answer 1

And debugging symbols (probably so named because of the way "STABS", for example, stored them in the symbol table) refers also to data above & beyond what the linker needs, such as line number/address mappings, type information, local variables, and lets not forget "static" symbols (which the linker clearly does not need, but which are obviously of great importance for debugging).

Of course, PE images don't need (or typically posses) "symbol tables" as such anyway -- just import/export tables. So, in the context of Windows, "symbols" and "debugging symbols" tend to be used interchangeably to refer to any symbols left over after linking; with MS's toolchain these (almost?) always go into "pdb" files. (See pdb-ms.)

Answer 2

A 'symbol' is a symbolic identifier including function and variable names.

The compiler/linker create a symbol table during the build and this is used by the debugger to provide source-level symbolic names to these entities, as opposed to plain addresses (hence the name "symbolic debugger" which you may come across).

Answer 3

Symbols are human names of variable, function, class... without symbols, you'll see everything just is data at address.
example:
with symbols:

call printf

without symbol

call dword ptr 0x804480 

Answer 4

They're entries in the code's symbol table, generated when compiling it. Variables, functions, etc.