sizeof(array) works in a block, but as a function parameter, it'll return sizeof(void*). i.e. void f(int a[4]) { printf("%d", sizeof(a)); } int main() { int b[

sizeof(array) works in a block, but as a function parameter, it'll return sizeof(void*). i.e. void f(int a[4]) { printf("%d", sizeof(a)); } int main() { int b[4]; f(b); } ... yields "4" (on my 32-bit machine)