View Compilation Error

0_0_36008106_26230.cpp: In function 'int main()':
0_0_36008106_26230.cpp:13:7: error: 'i' was not declared in this scope
   for(i=0;i<len;i++){
       ^
0_0_36008106_26230.cpp:18:12: error: expected ':' before ';' token
     case'B';r2=m2;
            ^