Question

I’m looking at stdint.h and given that it has uint16_t and uint_fast16_t, what is the use for uint_least16_t what might you want that couldn’t be done equally well with one of the other two?

Answer 1

Say you’re working on a compiler with:

• unsigned char is 8 bits
• unsigned short is 32 bits
• unsigned int is 64 bits

And unsigned int is the ‘fastest’. On that platform:

• uint16_t would not be available
• uint_least16_t would be a 32 bit value
• uint_fast16_t would be a 64 bit value

A bit arcane, but that’s what it’s for.

How useful they are is another story – I see the exact size variants all the time. That’s what people want. The ‘least’ and ‘fast’ versions I’ve seen used pretty close to never (it’s possible that it was only in example code – I’m really not sure).