View Compilation Error

0_0_36892674_28735.cpp: In function 'int main(int, char**)':
0_0_36892674_28735.cpp:12:3: error: 'len' was not declared in this scope
   len=strlen(str1);
   ^
0_0_36892674_28735.cpp:13:11: error: 'str' was not declared in this scope
   for(i=0;str[i]!='\0';i++)
           ^