View Compilation Error

0_0_17508645_25492.cpp: In function 'void gcd(int, int, int&, int&)':
0_0_17508645_25492.cpp:15:9: error: 'ngcd' was not declared in this scope
  return ngcd;
         ^
0_0_17508645_25492.cpp:15:9: error: return-statement with a value, in function returning 'void' [-fpermissive]