View Compilation Error

0_0_38407037_21999.cpp: In function 'int main()':
0_0_38407037_21999.cpp:11:3: error: expected ',' or ';' before 'for'
   for(int i=0;i<len-3;i++)
   ^
0_0_38407037_21999.cpp:11:15: error: 'i' was not declared in this scope
   for(int i=0;i<len-3;i++)
               ^