In C memory layout, where are static local variables and automatic local variables stored respectively?
Static local variables reside in the static data segment for the program's entire execution lifetime, whereas automatic local variables are dynamically allocated on the function activation stack frame.
What is the compilation result of attempting to declare 'static register int val;' inside a C function?
In C standard, a variable declaration can have at most one storage class specifier. Combining 'static' and 'register' causes a compilation error.
What happens to the caller variables 'a' and 'b' when calling 'swap(a, b)' where 'swap' is defined as 'void swap(int x, int y) { int t=x; x=y; y=t; }'?
Arguments in C are passed by value by default. The function swap operates on local copies 'x' and 'y', leaving 'a' and 'b' unchanged in the calling function.
What is the output of the following C program?
#include <stdio.h>
int main(void) {
extern int num;
printf("%d", num);
return 0;
}
int num = 85;The 'extern' keyword declares 'num' as a global variable defined elsewhere at file scope. The global definition 'int num = 85;' resolves the symbol.
Which of the following operations is illegal on a variable declared with the 'register' storage class specifier in C?
Because register variables may reside directly in CPU registers rather than RAM, applying the address-of operator '&' is strictly forbidden in C.