Suppose that on a platform, the minimal signed value is −2^15 = −32768 and the maximum value is 2^15 −1 = 32767. The constant 32768 then doesn’t fit into signed and is thus signed long. As a consequence, the expression -32768 has type signed long. Thus the minimal value of the type signed on such a platform cannot be written as a literal constant.

From Modern C by Jens Gustedt.

Its trivial to understand why 32768 is signed long, but why is -32768 also signed long and not signed, given the minimum signed value of -32768?

CodePudding user response：

Because -32768 is the unary operator - applied to 32768.

If you write e.g. ( ( - 32767 ) - 1 ), you get your constant in int type.

CodePudding user response：

If int is a 16-bit type in your platform then 32768 doesn't fit in it. Therefore 32768 must have the next larger type which is long. -32768 isn't a negative integer literal but a unary minus applied to the literal 32768. Since 32768 is long, so is -32768

This is exactly the same as

• -9'223'372'036'854'775'808LL is unsigned
• Why does the smallest int, −2147483648, have type 'long'?
• Why does MSVC pick a long long as the type for -2147483648?