C calculate values with different datatypes

Asked Sep 22 '14 at 22:47

Active Sep 22 '14 at 22:49

Viewed 39 times

I just try to calculate this on my microcontroller programm:

uint16_t aOffset = 0;
uint16_t bOffset = 0;
uint16_t a = 530;
uint16_t b = 530;
int16_t aReal = a - aOffset;
int16_t bReal = b - bOffset;
int32_t c = (int32_t) aReal * bReal;

printf("%d, %d, %d\n", aReal, bReal, c);

And the output is:

530, 530, 18756

But the output should be:

530, 530, 280900

What's wrong here?

asked Sep 22 '14 at 22:47

stonar96

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Cannot reproduce. This prints "`530, 530, 280900`" on my machine. – jwodder Sep 22 '14 at 22:49
1

try `printf("%" PRId16 ", %" PRId16 ", %" PRId32 "\n", aReal, bReal, c);` – BLUEPIXY Sep 22 '14 at 22:54
@BLUEPIXY: Or cast to `long` and use `"%ld"`. – Keith Thompson Sep 22 '14 at 22:56

C calculate values with different datatypes

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