### 4.2 Global Variables ¶

A variable whose scope is not specific to just one source file is represented by the ‘`G`’ symbol descriptor. These stabs use the `N_GSYM` stab type (C_GSYM for XCOFF). The type information for the stab (see The String Field) gives the type of the variable.

For example, the following source code:

    char g_foo = 'c';

yields the following assembly code:

    .stabs "g_foo:G2",32,0,0,0     # 32 is N_GSYM
         .global _g_foo
         .data
    _g_foo:
         .byte 99

The address of the variable represented by the `N_GSYM` is not contained in the `N_GSYM` stab. The debugger gets this information from the external symbol for the global variable. In the example above, the `.global _g_foo` and `_g_foo:` lines tell the assembler to produce an external symbol.

Some compilers, like GCC, output `N_GSYM` stabs only once, where the variable is defined. Other compilers, like SunOS4 /bin/cc, output a `N_GSYM` stab for each compilation unit which references the variable.