Output of the expression (3^6)+(a^a) in C language?

Question

I am an amateur C programmer and I encountered this question in a book,can someone give me its valid explanation. I am getting confused as to what this ^ sign is doing in a C program.

#include <stdio.h>

int main(void)
{
    int a;
    printf("%d", (3^6) + (a^a));
    return 0;
}

Answer 1

int a;
printf("%d",(3^6)+(a^a));

The evaluation of the (3^6)+(a^a) expresion invokes undefined behavior as a is not initialized and has an indeterminate value.

(C11, 6.3.2.1p2) "If the lvalue designates an object of automatic storage duration that could have been declared with the register storage class (never had its address taken), and that object is uninitialized (not declared with an initializer and no assignment to it has been performed prior to use), the behavior is undefined."