Passing strings to functions and modifying them

Hey all
This is a newbie question... I want to pass a couple of strings to a function and then have that function modify them. The function isn't returning anything, just modifying the strings... when I call the strings again from my main program, they haven't changed. If I print em out from within the function, they have changed. So what's the correct way to pass the address of those strings so I can change em?

Thanks
d02

If you are passing a char array or a char *, then any changes made in the function will be seen in the main program.

Unfortunately this not what I'm seeing.

Code:

---

void changeString (char* chSt)
{
        chSt = "blah";
}

int main(int argc, char** argv)
{
        char* chSt = "-";
        changeString (chSt);
        printf("%s", chSt);
       
        return 0;       
}

---

will output "-"

TiA
d02

Remember the rules for function parameters: you can change what is pointed to, you cannot change what is passed in.

You can modify the string pointed to in a function, and that works just fine. You cannot just try to make the pointer point to some completely different place, and expect that to work (that tries to modify the passed-in pointer). If you want to make the pointer point somewhere else, you must pass it in pointer-to-pointer.

As you may or may not know, "string literals" are/can be stored in read-only memory, so any attempt to modify them will die a horrible death (at least we don't blue screen anymore, just that little box).

Oh, and I suppose I should mention that = is not really considered a valid way to assign a string in C, except in the passing-around-pointers-to-constant-chars sense -- strcpy is generally used.

Thanks, that explanation really helped out!

http://cpwiki.sourceforge.net/Common...kes_and_errors
This code can't modify the string because you're using string literals. And they should be const.