How to change the actual argument passed to a function in C?

Question

I want to change the actual argument passed to a function and not a copy of it. For example:

char str[] = \"This is a string\";

I want to c

Answer 1

I think you mean something like this:

void update_string(char ** ptr)
{
    *ptr = strdup("This is a test");
    return;
}

Then call the function like this:

char * str = strdup("hello world\n");
printf("%s\n", str);
update_string(&str);
printf("%s\n", str);