View Compilation Error

0_0_23027658_23625.c: In function 'main':
0_0_23027658_23625.c:12:10: error: 'b' undeclared (first use in this function)
   memset(b,0,sizeof b);
          ^
0_0_23027658_23625.c:12:10: note: each undeclared identifier is reported only once for each function it appears in