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cpointersmemoryconstantsmemory-address

The memory address of constants in C

I'm learning about pointers in C and I've got a few questions. Here's a piece of code just for an example.

int var = 300;
char s[] = "Clang";
char *p  = "Wonder";

I know that all the variables have their addresses in memory. The variables like var and s and p have their own addresses in memory.

But I wonder if constants have memory addresses as well.

Do 300,"Clang", "Wonder" themselves have memory addresses?

Solution

  • Only objects and functions have addresses in C. Named variables are objects. A string literal "Wonder" used by itself is an object, an array of 7 characters (i.e. char[7]) - the 6 visible characters and the terminating null character - and therefore may have an address. The literal "Clang" is a borderline case here, strictly speaking it does not have an address because it is not an object but just a special initializer syntax.

    The C model is quite unlike Python programming language, where

    a = 300

    a is a name that has no address, whereas 300 is an object that has an address.

    The may is because while C says that an object or function has an address, many compilers optimize code, creating an executable that does not follow the strict C abstract machine; therefore an object might have an address only if you observe it.