Hello everyone
I am taking a compilers course and have stumbled on a problem which I
am unable to resolve. Here is the code I am dealing with:
/* f1.c */
#include <stdio.h>
double c;
int main() {
c = 1;
printf("sizeof(c) = %lu\n", sizeof(c));
return 0;
}
/* f2.c */
int c = 0;
I compile the program using gcc f1.c f2.c. From what I have learnt, I
believe that the output of the file should be sizeof(c) = 4 since the
declaration of c in f1.c is weak and would be resolved to the symbol c
in file f2.c which is strong. I also checked the symbol table using
the readelf utility which also shows that the size of c is 4. Here is
a snippet of the output from readelf -s ./a.out:
Num: Value Size Type Bind Vis Ndx Name
--------------------------------------------------------------
61: 0000000000400430 42 FUNC GLOBAL DEFAULT 14 _start
62: 000000000060103c 4 OBJECT GLOBAL DEFAULT 26 c
63: 0000000000601038 0 NOTYPE GLOBAL DEFAULT 26 __bss_start
--------------------------------------------------------------
But the output from the program is sizeof(c) = 8. Could someone please
explain this behavior? I am using Ubuntu 16.04, gcc version 5.4.0
Thank You
--
Lakshay G.
