View Compilation Error

0_0_20599021_28133.cpp:6:11: error: variable or field 'swap' declared void
 void swap(x, y){  
           ^
0_0_20599021_28133.cpp:6:11: error: 'x' was not declared in this scope
0_0_20599021_28133.cpp:6:14: error: 'y' was not declared in this scope
 void swap(x, y){  
              ^
0_0_20599021_28133.cpp: In function 'void shiftDown(int)':
0_0_20599021_28133.cpp:33:22: error: 'swap' was not declared in this scope
             swap(x, t);  
                      ^