return(sizeof(array)) gives unexpected result [duplicate]

Question

I wrote the following program to determine the size of a static array. When I ran it, I got a result I can't explain. I've done some searching on stackexchange and google, but nothing I've read has given me a hint.

#include <stdio.h>
int main()
{
  int arrSize, intSize, elemSize;
  int input[9][9];
  arrSize = sizeof(input);
  intSize = sizeof(int);
  elemSize = sizeof(input[0]);
  printf("Array: %d, Element: %d, Int: %d\n", arrSize, elemSize, intSize);
  return sizeof(input);
}

When I compile and run this program, I get the following result (using linux):

./a.out ; echo $?
Array: 324, Element: 36, Int: 4
68

I see from http://c-faq.com/malloc/sizeof.html that sizeof is computed at compile time, and if I change the return to return sizeof(input[0]) I get 36 which is expected, and I get 4 if I change it to return sizeof(input[0][0]) as expected. So why does sizeof(input) give 68 in the return, but when stored it gives the expected 324?

Answer 1

The exit code for your system must be max 255 we can see that 324 % 256 = 68.

Answer 2

After a child process terminated, its parent process could get the status information of this child process by

waitpid(-1, &status, 0);

And the return status could be extracted from status by WEXITSTATUS(status), according to waitpid(2) this macro

returns the exit status of the child. This consists of the least significant 8 bits of the status argument that the child specified in a call to exit(3) or _exit(2) or as the argument for a return statement in main().

Therefore, if your main() returns 324, the return code you get from shell would be 324 % 256, i.e. 68.