S12 / MagniV MicrocontrollersのトピックRe: Basic question on pointers....

Basic question on pointers....

FIDDO — Tue, 10 Jun 2014 04:20:39 GMT

Consider the following example

void tester(unsigned char *);

void main()

{

unsigned int test,y;

tester(&test);

y=test

}

void tester( unsigned char *x)

{

*x=36;

}

What will be the value of y now?

whether address of test will be removed from the subroutine void tester once its exits!!

Please clarify!

Re: Basic question on pointers....

ah — Thu, 12 Jun 2014 20:31:15 GMT

Value of y will be 36.

the address of variable test is taken as the value x is pointing to. so the address of variable will hold value 36.

as y is assigned to test, y becomes 36.

I hope it helps.

-AH

Re: Basic question on pointers....

StenS — Tue, 17 Jun 2014 05:06:11 GMT

Not quite true! y and test are of type unsigned int (16 bits) while the argument to the tester-routine is a pointer to an unsigned char. The compiler will probably give you a warning, but will compile and the program will run. Since the Freescale-controllers are big-endian, the tester-routine will write the number 36 to the most significant byte of the test-integer, giving a result of 0x2400 = 9216.

/Sten