Declaration of arrays before "normal" variables in c?
- by bjarkef
Hi
We are currently developing an application for a msp430 MCU, and are running into some weird problems. We discovered that declaring arrays withing a scope after declaration of "normal" variables, sometimes causes what seems to be undefined behavior. Like this:
foo(int a, int *b);
int main(void)
{
int x = 2;
int arr[5];
foo(x, arr);
return 0;
}
foo sometimes is passed a pointer as the second variable, that does not point to the arr array. We verify this by single stepping through the program, and see that the value of the arr variable in the main scope is not the same as the value of the b pointer variable in the foo scope. And no, this is not really reproduceable, we have just observed this behavior once in a while.
Changing the example seems to solve the problem, like this:
foo(int a, int *b);
int main(void)
{
int arr[5];
int x = 2;
foo(x, arr);
return 0;
}
Does anybody have any input or hints as to why we experience this behavior? Or similar experiences? The MSP430 programming guide specifies that code should conform to the ANSI C89 spec. and so I was wondering if it says that arrays has to be declared before non-array variables?
Any input on this would be appreciated.
