View Compilation Error

0_0_13156994_10090.cpp: In function 'void reverse(char*)':
0_0_13156994_10090.cpp:15:29: error: 'strlen' was not declared in this scope
  for ( i = 0; i < strlen(str); i++ ) tmp[strlen(str) - i - 1] = str[i];
                             ^
0_0_13156994_10090.cpp:16:29: error: 'strlen' was not declared in this scope
  for ( i = 0; i < strlen(str); i++ ) str[i] = tmp[i];
                             ^
0_0_13156994_10090.cpp: In function 'int main()':
0_0_13156994_10090.cpp:39:27: error: 'memset' was not declared in this scope
   memset( a, 0, sizeof(a) );memset( b, 0, sizeof(b) );memset( c, 0, sizeof(c) );
                           ^
0_0_13156994_10090.cpp:45:33: error: 'strlen' was not declared in this scope
   for ( i = 0; i < min( strlen(a), strlen(b) ); i++ )
                                 ^
0_0_13156994_10090.cpp:51:20: error: 'strlen' was not declared in this scope
   maxc = ( strlen(a) > strlen(b) ) ? a : b;
                    ^