I'm having some trouble wrapping my head around this simple dereferencing statement.
I've tried printing **names, and then I get what I expect to get from *names -- 'C'. However, *names gives me 'D'.
#include <stdio.h>
int main(void)
{
char *names[] = {"Carl", "David", "Gibson", "Long", "Paul"};
printf("%c\n", *names);
return 0;
}
The console prints out 'D'. I'm not sure why the resulting char from *names is not the first letter of the first item, 'C'.
This is undefined behavior and the output varies with the compiler.
When I run this with gcc, there is no output. Using **names prints 'C'.
The undefined behavior is because of the wrong format specifier. You use %c, but *names point to the first element in the array, ie a char array storing "Carl".
Use the %s format specifier to print strings.
printf("%c\n", *names);
When you compile this code, GCC will give you the following:
test.c:5:12: warning: format ‘%c’ expects argument of type ‘int’, but argument 2 has type ‘char *’ [-Wformat=]
printf("%c\n", *names);
~^ ~~~~~~
%s
So you're basically trying to print the first character of the first name, but instead of passing a char as an argument, your're passing a pointer to char. What you could do is this:
printf("%c\n", *names[0]);
in which you specify that you want the first character from the first element.
Also, using **names is the same as using *names[0]
printf("%s\n", *names);orprintf("%c\n", **names);%cformat specifier expects a single character (an integer argument toprintf). The%sformat specifier expects a string (achar *). You're passing achar *to a%cspecifier, which makes no sense. Your compiler should have warned about this (make sure your code is clear of warnings before posting here, unless you truly don't understand the warning, in which case that should be the title of your post).printf("%c\n", (*(names[1]+(sizeof(char)*2))));where the1represents the second name in the array, and the2represents the letter within the name. This would outputvfromDavid. Or alternatively, just use%s;).sizeofout, pointer arithmetic already scales by the element size. The only reason it isn't blowing up in your face is thatsizeof(char)is guaranteed to be 1.