Recursive Function Loop Through Character Array

Question

I have an assignment where I'm supposed to loop through a Character Array using a Recursive Function. I figured it would be easy since I would know the length of the array but then the prototype is give to me which I have to use:

void display(char str[])

I can't imagine how I'm supposed to loop through this recursively without knowing the length. Can anybody give me a nudge on this please?

Answer 1

void display(char str[])
{
    if (*str) {
        putchar(*str);
        display(str+1);
    }
}

Answer 2

C strings (assuming your character array is a C string) are assumed to be null terminated. So, you could, for instance, use a recursive function to compute the length and look for the null character for your base case to know you are done.

Answer 3

As mentioned by @abelenky and @Nathan, a character array is assumed to end with a "null" char (usually '\0').
Here's an example on how to find the number of characters

 unsigned int strLen( const char[] str ) {
     unsigned int len = 0;
     while( str[len] ) {
         len++;
     }
     return len;
 }