|signed specifier||Signed integer type specifier|
simple-type-specifier := signed
The signed keyword can be used alone to mean signed int or combined with other type specifiers to force the type to be signed. The int, short, and long types are implicitly signed, so it is most often used with signed char to implement a signed integral value whose range is the smallest that the compiler allows.
A signed integer can be represented using two's complement, ones' complement, or signed magnitude.
char, int, long, short, type, unsigned, Chapter 2