Question

Is it OK that a char* variable will point to a string (that’s written in the source code)?
Can I manipulate/modify the space allocated for the literal string as long as I’m not exceeding it’s length?
As much as I understand the format of an executable, it’s fine, but I want to be sure. Thank you 🙂

Answer 1

Depends a bit on your runtime characteristics, but in general, doing something like:

char *s = "a literal string";
s[3] = 'q';

will compile, but not work at runtime. The literal string in this case is generally in a read-only section of the executable. The following example, however, will work:

char s[] = "a literal string";
s[3] = 'q';

In this case, the literal string is an initialiser for an array (s) on the stack. So the answer to your first question is “yes” and the answer to your second question is “maybe”.

There is a semantic difference between the two examples. The first one creates a pointer to a literal string, and the second creates an array and initialises it with the contents of a literal string.