Solaris Linux Environment - Writing, Compiling and Running C++ and C Programs

CentOS Linux Environment

• Open the terminal window.
  Click on the background screen (blue screen). A menu will appear. Click on open terminal
• Check that you are in your home directory using the UNIX command pwd, if not use the UNIX command cd to get to your home directory.
• It is sensible to make a directory for all your C++ or C programming work, e.g. type the UNIX command
  
  mkdir CPP_Prog
  
  Generally, you may call the exercise directories by whatever names you wish within the UNIX rules. It is usual practice to name directories with a name that indicates their contents, e.g. CPP_Prog in the above case. A course lecturer may ask you to use specified names for some of your sub-directories if he or she is going to collect your course assignments directly from your home directory. In such cases it is important that you name the relevant directories exactly as requested paying attention to the case (upper or lower) of the letters of the specified names.
• To enter the directory CPP_Prog, type the UNIX command
  
  cd CPP_Prog
  
• The UNIX command, ls, will list all the directories and files in the directory in which you are currently working.

• Open the file browser.
  You may do this from the tool bar at the top of the screen (Application and then File Browser) or by clicking on the xxx's Home Folder icon where xxxx is your user name.
• It is sensible to make a directory for all your C++ or CPP programming work. Click on File on the menu bar. Then click on New Folder... in the drop-down menu. Type in the name of the folder, i.e. your new directory, in the dialogue box that now appears. It is helpful if you use a meaningful name e.g. CPP_Prog. Now click on the OK button. A course lecturer may ask you to use specified names for some of your sub-directories if he or she is going to collect your course assignments directly from your home directory. In such cases it is important that you name the relevant directories exactly as requested paying attention to the case (upper or lower) of the letters of the specified name.
• To display the contents of the directory, CPP_Prog, double click on the CPP_Prog icon now displayed in your home directory. It will at this point be empty.

• Click on Applications
• Click on Accessories
• Click on Text Editor

• Click on File in the menu bar at the top of the Text Editor Window.
• Click on the Open... command in the drop-down menu that appears.
• A Dialogue Box now appears.
• Double click on the directory you wish to open. You WILL often need to change to the directory in which you save your files. Otherwise they will most likely end up in your home directory and not in the Exercise directory you made earlier.
• Double click on file you wish to open.

• C program compilation
  The present standard compiler requires a compile command cc (see below). The lower case is obligatory for C program compilation. The second, i.e. gnu, compiler requires a compile command gcc (lower case). If you are using the gnu compiler, replace cc by gcc in all the commands listed below.
• C++ program compilation
  Replace the lower case, cc, by upper case, CC, in the commands listed below to use the C++ compiler.

• The preprocessor/compiler copies your source code.
• The code is first examined by the preprocessor which works on the copy leaving your source as written.
• The preprocessor looks for include and define, i.e. #, statements and replaces the with appropriate code. The preprocessor passes the amended copied code to the compiler.
• The compiler starts the compilation, checking for errors.
• If no errors - compiler converts source code into object code.
• If errors - compiler displays error message/s.
• The linker combines object code with code required from libraries to produce an executable file.

• 3.3.1 Compilation and linking in one step with a named executable file
  
  cc -o "executable file name" "C source file name"
  e.g. cc -o hello hello.c
  
  Compiles and links source hello.c and makes executable file hello, i.e. sets the output (-o) file to be called hello. It is conventional to call the executable file by the same name as the source file but without its .c extension.
  
  Check any error messages and go back to editor to make changes if required then save and compile file again.
  NB Always save the most recent version before compiling!
  
  Check your directory contents using either the UNIX command ls or the file manager.
  You should now have hello* (in the ls listing) or the hello icon with a lightning strike on it (in the file manager window) amongst your files, this is the EXECUtable FILE.
  
  
• 3.3.2 Compilation and linking in one step without naming the executable file
  
  cc "C source file name"
  e.g. cc hello.c
  
  Compiles and links source hello.c and makes executable file with the default name a.out. Check your directory contents as above.
  You should now have a.out* (in the ls listing) or the a.out icon with a lightning strike on it (in the file manager window) amongst your files, this is the EXECUtable FILE.
  
  You may rename a file using the either the terminal window or the file manager. The UNIX command is
  
  mv "old name" "new name"
  e.g. mv a.out hello
  
  You can change a file name in file manager by clicking on the file icon, then clicking on Selection on the menu bar and then on Rename . . . in the drop-down menu. The cursur is now position within the file icon for you to change the name.
  
  
• 3.3.3 Compilation without linking
  
  cc -c "C source file name"
  e.g. cc -c hello.c
  
  Compiles the source hello.c and makes an object file with the default name hello.o. Check your directory contents as above.
  You should now have a file called hello.o amongst your files, this is the object file.
  
  
• 3.3.4 Linking an object file to make an executable file
  
  cc -o "executable file name" "object file name"
  e.g. cc -o hello hello.c
  
  Links the object file hello.o and makes an executable file hello.

1. include the math.h header file, i.e. #include <math.h>
2. instruct the linker to include the math library
   e.g. if program xxx.c includes the math.h header then the cc compile instruction becomes
   cc -o xxx xxx.c -lm
   The command -lm (minus lowercase el lowercase em) must come last as it is an instruction to the linker and not to the compiler.
   Specific linking, via -lm, of the math library is true of all UNIX C compilers, e.g. cc and gcc, but is not generally true of non-UNIX C compilers, e.g. Microsoft Visual C++.

• Open the terminal window if not already open.
• Go to the directory in which the executable file is stored (cd command).
• Type the name of the executable file, e.g. hello in the above examples, followed by a return.
• The program will now execute.
• If execution unsuccessful, edit the source file to correct errors and recompile. NB section 3.5 above.