Difference between char[] and char * in C [duplicate]

Question

What is the difference between char[] s and char * s in C? I understand that both create make 's' a pointer to the array of characters. However,

char s[] = "hello";
s[3] = 'a';
printf("\n%s\n", s);

prints helao,while

char * s = "hello";
s[3] = 'a';
printf("\n%s\n", s);

gives me a segmentation fault. Why is there such a difference? I'm using gcc on Ubuntu 12.04.

Answer 1

When using char s[] = "hello";, the char array is created in the scope of the current function, hence the memory is allocated on the stack when entering the function.

When using char *s = "hello";, s is a pointer to a constant string which the compiler saves in a block of memory of the program which is blocked for write-access, hence the segmentation fault.