Where are literal strings placed and why can I return pointers to them?

Question

I stumbled upon this function in an answer to this question:

/* Note: I\'ve formatted the code for readability. */
const char * getString() {
    const char *x =         


        

Answer 1

In C, string literals have static storage duration. Your code is logically equivalent to:

const char * getString() {
    static const char literal[] = "abcstring";
    const char *x = literal;
    return x;
}

with the exception that in the version with the string literal, the storage for the string could overlap with the storage of other string literals.

Answer 2

It varies per ABI, but on x86 they're in static memory/DATA page, pointed to by the DS register.

Answer 3

As an addendum to most of the other answers, you can look at the assembler the compiler generates (e.g. by passing -S to GCC) to see how they are stored. Putting your function into a file by itself, we find that GCC basically generates (I've removed some irrelevant stuff):

.section        .rodata
.LC0:
        .string "abcstring"
        .text

        .globl  getString
        .type   getString, @function
getString:
        # load the address of ".LC0" which is the start of the "abcstring"
        movl    $.LC0, %eax 
        ret

So the string is stored in the .rodata section ("read-only data"), not on the stack and so it has a "global" address (and is always in scope).

Similarly, the string literal in myfunc("thisisastring") is also placed into a .rodata section, and is not on the stack.