C interpretation of hexadecimal long integer literal “L”

Question

How does a C compiler interpret the \"L\" which denotes a long integer literal, in light of automatic conversion? The following code, when run on a 32-bit platform (32-bit long

Answer 1

It's a hexadecimal literal, so its type can be unsigned. It fits in unsigned long, so that's the type it gets. See section 6.4.4.1 of the standard:

The type of an integer constant is the first of the corresponding list in which its value can be represented.

where the list for hexadecimal literals with a suffix L is

1. long
2. unsigned long
3. long long
4. unsigned long long

Since it doesn't fit in a 32-bit signed long, but an unsigned 32-bit unsigned long, that's what it becomes.

Answer 2

The thing is that the rules of determining the type of the integral literal are different depending on whether you have a decimal number or a hexadecimal(or octal number). A decimal literal is always signed unless postfixes with U. A hexadecimal or octal literal can also be unsigned if the signed type can not contain the value.