View Compilation Error

0_0_33081240_19500.cpp:12:11: error: '::main' must return 'int'
 void main()
           ^
0_0_33081240_19500.cpp: In function 'int main()':
0_0_33081240_19500.cpp:19:26: error: 'strlen' was not declared in this scope
     int length=strlen(str);
                          ^