Amumu - 5 months ago 42

C Question

So the reason for

`typedef`

`uint64_t`

`long long`

However, there is

`uint_fast32_t`

`typedef`

`uint32_t`

Answer

`int`

may be as small as 16 bits on some platforms. It may not be sufficient for your application.`uint32_t`

is not guaranteed to exist. It's an optional`typedef`

that the implementation must provide iff it has an unsigned integer type of exactly 32-bits. Some have a 9-bit bytes for example, so they don't have a`uint32_t`

.`uint_fast32_t`

states your intent clearly: it's a type of*at least*32 bits which is the best from a performance point-of-view.`uint_fast32_t`

may be in fact 64 bits long. It's up to the implementation.

... there is

`uint_fast32_t`

which has the same typedef as`uint32_t`

...

What you are looking at is not the standard. It's a particular implementation (BlackBerry). So you can't deduce from there that `uint_fast32_t`

is always the same as `uint32_t`

.

See also: