Menu
int is 32 bits in size. long , ptr , and off_t are all 64 bits (8 bytes) in size.
The size of a signed int or unsigned int item is the standard size of an integer on a particular machine. For example, in 16-bit operating systems, the int type is usually 16 bits, or 2 bytes. In 32-bit operating systems, the int type is usually 32 bits, or 4 bytes.
The simplest way to get the multiplication to happen in an unsigned type that is at least uint32_t, and also at least unsigned int, is to involve an expression of type unsigned int.
v = 1U * s1 * s2;
This either converts 1U to uint32_t, or s1 and s2 to unsigned int, depending on what's appropriate for your particular platform.
@Deduplicator comments that some compilers, where uint32_t is narrower than unsigned int, may warn about the implicit conversion in the assignment, and notes that such warnings are likely suppressable by making the conversion explicit:
v = (uint32_t) (1U * s1 * S2);
It looks a bit less elegant, in my opinion, though.
Congratulations on finding a friction point.
A possible way:
v = (uint32_t) (UINT_MAX<=0xffffffff
? s1 * s2
: (unsigned)s1 * (unsigned)s2);
Anyway, looks like adding some typedefs to <stdint.h> for types guaranteed to be no smaller than int would be in order ;-).
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With