Question

In my code I have

char* s = strchr(first,'/');
if(s==NULL) s = "";
else s = s+1;

But my gcc compiler complains at the penultimate line with

warning: assignment discards qualifiers from pointer target type

From what I understand about ANSI C, it is because I am setting s (a non-const value) to a string literal (a const value). (Am I wrong here?) Yet I need s to be non-const (because I may be changing its value by adding 1 to it), and I also need to set s to an empty string literal. Do I have any options in terms of better code design here to achieve these two objectives without the compiler yelling?

I do have the -Wwrite-strings flag enabled.

Answer 1

You should use strcpy instead of assigning string literals. The problem is that the string literal is constant, and s will contain the address of that string, not the string itself, which is bad.

For example if you have:

char str[100];
str = "Hello world";

The address of the 100 char’s allocated will be replaced with the address of "Hello world" constant string.

Easiest way to make a string empty is to set the first value to NULL (*s = NULL);