On 2017-02-16 22:54 +0800, Xi Ruoyao wrote: > According to the Standard, '32768' is a decimal literal, but '-32768' > is not. It's an expression using unary '-' to the literal '32768'. > Here '32768' has type int32_t. So the expression also has type > int32_t despite the result can fit into an int16_t. It's called 'literal' in C++ Standard. In C Standard it's just called integer constant. For example, in C99 6.4.4.1 the grammar of decimal-constant is: decimal-constant: nonzero-digit decimal-constant digit We can see a decimal constant must begin with a nonzero-digit, '-' is not a nonzero-digit. So '-32768' is not a decimal-constant. The description of 6.4.4.1 also said: An integer constant begins with a digit. -- Xi Ruoyao <ryxi@xxxxxxxxxxxxxxxxx> School of Aerospace Science and Technology, Xidian University
