c++ - Why does bitwise AND operation 16 & 017 give an unexpected result? -

i have following code:

#include <iostream> using namespace std;  int main() {     int val = 16;     printf("%d\t%d\t",val,val & 017);      return 0; } 

why output

16   0 

and not

16   16 

as expect boolean operation

16 , 17 = 16 

the literal 017 interpreted octal representation because starts 0. details on see e.g. here. note that

(17)_8 == (15)_10 == (1111)_2 

and (16)_10 == (10000)_2 result clear.