Question

I have a character arraym
char Input[200];

input as of now has the string “abc.txt”.

I have a method that strictly needs a const char *, how can I convert my input array into a const char *.

I tried casting it, and passing it, but upon using GDB, I feel like since the remaining 192 slots in input are filled with garbage(or are empty)its not being accepted by the function. When I pass the string literal “a.txt” to the function it works. so at this point I would like to extract the filled up elements from input array and convert it to a const char *.

I am taking input as a filename from a user, so I used a char array to store the input.

   int main()
    {
    char *name;

    char input[1024];
    strcpy(input, argv[1]);

    name = input;

    sys_open(input, "O_RDWR", 00700);


    }

Answer 1

You should be able to pass it directly. A char[] can be cast to a const char *, but not vice versa.

The reason that you see all of the garbage in gdb is because arrays are not pre-initialized to contain anything, so you’re just seeing whatever garbage was in there before. As long as your string is null-terminated, it should be fine.