C語言中 sizeof 特殊用法
阿新 • • 發佈:2018-12-19
6.23 Arithmetic on void
- and Function-Pointers
In GNU C, addition and subtraction operations are supported on pointers to void
and on pointers to functions. This is done by treating the size of a void
or of a function as 1.
A consequence of this is that sizeof
is also allowed on void
and on function types, and returns 1.
The option -Wpointer-arith requests a warning if these extensions are used.
typedef int boot_os_fn (int flag, int argc);
sizeof(boot_os_fn) 大小為 1
sizeof(void) 大小為 1
基本疑惑在函式型別上
typedef int(*boot_os_fn) (int flag, int argc);
sizeof(boot_os_fn) 大小為 4 或者8 32bit or 64bit 系統上