View Compilation Error

0_0_24895937_24128.cpp: In function 'int main()':
0_0_24895937_24128.cpp:11:23: error: 'strlen' was not declared in this scope
         a_len=strlen(a);
                       ^
0_0_24895937_24128.cpp:68:3: error: expected '}' at end of input
   }
   ^