Header files (answers to jit-anonymous questions) Angle brackets <> specify header files found in standard locations, double quotes “” specify current directory (or non standard location) <iostream.h>, <ctype.h> “ctimer.h”, “date.h” in new versions of C++, the .h isn’t used for standard C++ classes, e.g., <iostream>, <string>, STL <vector> on our system these files just use #include <iostream.h>, but could pre-compile or otherwise optimize the headers on other system using the .h puts classes into the global namespace, otherwise must qualify use: std::cout vs cout

Standard/STL classes vs libtapestry classes libtapestry strings aren’t as efficient, e.g., no sharing on assignment reference counted, shared storage copy on write always copy (libtapestry) shared vs static libraries static code stored in executable when compiled shared/dynamic linked when program run advantages? string a = “hello”; string b = a; “hello” libtapestry.a a b “hello” standard (libg++.so) “hello” a b b[0] = ‘j’; // what happens?

STL classes (e.g., vector) In general, the STL classes aren’t safe, e.g., bad index not checked on our systems, a “safe” version of classes can be used by using #define __STL_DEBUG before any #include specific differences in STL vector vs libtapestry vector STL libtapestry size() length() push_back() append() append/push_back works differently: size() in libtapestry is number of times append called libtapestry vector, map, stack, queue are as efficient as STL classes (sometimes more efficient) and are safe

Using the system, dot files The shell is the program you type commands at different shells: sh, csh, bash, ksh, tcsh use tcsh unless you’re positive you want something else the shell looks at your PATH environment variable to determine where commands you type are found uses directories specified in left-to-right order setenv PATH /afs/acpub/project/cps/bin:${PATH} also /bin/sh variable called path (lower case) set differently .cshrc file, used each time you start a shell .login file, used when you log in .emacs file, used when you launch emacs/xemacs