alt Hacker NewsThe C language does not have any data type that has the property "can't be negative".
Signed integers can be negative. The so-called "unsigned" integers of C are integer residues modulo 2^N, which are neither positive nor negative, i.e. these concepts are not applicable to "unsigned" integers.
An alternative view is that any C "unsigned" is both positive and negative. For example the unsigned short "1" is the same number as "65537" and as "-65535".
So any sizeof value in C is negative (while also being positive).
In contradiction with what you say, the change described in TFA, by making sizes 64-bit signed integers, is the only method to guarantee that the sizes are non-negative in a language that does not have dedicated non-negative integers.
Other programming languages have non-negative integers, but C and C++ and many languages derived from them do not have such integers.
The arithmetic operations with non-negative integers differ from the arithmetic operations of C. On overflows and underflows, they either generate exceptions or have saturating behavior.
Replies
Are you claiming that the following program could possibly print "-1" ?
#include <stdio.h>
int main() {
unsigned short a = 1;
long b = a;
printf("%ld\n", b);
}
Leaving aside the fact that, yes, unsigned integer types are definitely not negative -- my point wasn't about types at all. Objects cannot take up a negative number of bytes of memory!
> An alternative view is that any C "unsigned" is both positive and negative. For example the unsigned short "1" is the same number as "65537" and as "-65535".
This can be disproven by the fact that dividing by `unsigned e = 1U` is well defined and always yields the starting number. If the unsigned numbers were really modular numbers as you suggest, division could not be defined.