C++ – static variables stored in C and C++

ccompiler-construction

In what segment (.BSS, .DATA, other) of an executable file are static variables stored so that they don't have name collision?
For example:


foo.c:                         bar.c:
static int foo = 1;            static int foo = 10;
void fooTest() {               void barTest() {
  static int bar = 2;            static int bar = 20;
  foo++;                         foo++;
  bar++;                         bar++;
  printf("%d,%d", foo, bar);     printf("%d, %d", foo, bar);
}                              }

If I compile both files and link it to a main that calls fooTest() and barTest repeatedly, the printf statements increment independently. Makes sense since the foo and bar variables are local to the translation unit.

But where is the storage allocated?

To be clear, the assumption is that you have a toolchain that would output a file in ELF format. Thus, I believe that there has to be some space reserved in the executable file for those static variables.
For discussion purposes, lets assume we use the GCC toolchain.

Best Answer

Where your statics go depends on whether they are zero-initialized. zero-initialized static data goes in .BSS (Block Started by Symbol), non-zero-initialized data goes in .DATA

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