15 Aug
2024
15 Aug
'24
11:54 p.m.
On 08/15/2024 6:10 PM EDT Mike Katz via cctalk
<cctalk(a)classiccmp.org> wrote:
I'm pretty certain you are wrong about the byte case below. The C standard says
something about no math will be done smaller than a short. I don't have it handy so
can't quote exactly.
But what that means is before the two bytes are added, they are promoted to short /
uint16_t and then added.
int foo( void )
{
uint32_t Long1 = 10;
uint32_t Long2 = 20;
uint16_t Short1 = 10;
unit16_t Short2 = 20;
uint8_t Byte1 = 10;
uint8_t Byte2 = 20;
//
...
// Everything to the right of the equals will not be
promoted at
all, the math will be performed and the result will be promoted to a
uint16 when assigned.
//
Short1 = Byte1 + Byte2;
In this program segment:
uint8_t a = 255;
uint8_t b = 255;
uint16_t c = 0;
c = a + b;
printf("c: %d \n", c);
it will print 510 instead of the 254 that would result if it were added as bytes.
Will
Grownups never understand anything by themselves and it is tiresome for children to be
always and forever explaining things to them,
Antoine de Saint-Exupery in The Little Prince