View Compilation Error

0_0_29285783_22972.cpp: In function 'int main()':
0_0_29285783_22972.cpp:13:31: error: 'memset' was not declared in this scope
   memset(str1, 0, sizeof(str1));
                               ^
0_0_29285783_22972.cpp:15:23: error: 'strlen' was not declared in this scope
   int len1 = strlen(s1), len2 = strlen(s2);
                       ^
0_0_29285783_22972.cpp:16:20: error: 'strcmp' was not declared in this scope
   if (strcmp(s1, s2) == 0)
                    ^
0_0_29285783_22972.cpp:18:49: error: 'len2' was not declared in this scope
   else if (s1[0] != s2[0] || s1[len1 - 1] != s2[len2 - 1]) {
                                                 ^
0_0_29285783_22972.cpp:24:23: error: 'len2' was not declared in this scope
   for (int i = 0; i < len2; i++)
                       ^