Advanced UNIX Programming: Week 1 Topics and UNIX Programming Environment, Slides of Computer Programming

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Advanced UNIX progamming

Week 1 Topics

• Course outline and policies
• UNIX programming environment
  • Editors
  • C compilers and debuggers
  • Makefiles
• Review some features of C
  • Header files
  • Command line arguments
  • Utilities
• Review some UNIX system calls
  • system, etc

Editors

• vi, pico, emacs , etc
• What is good about emacs?
  • emacs is more than just an editor
  • You can compile and edit within emacs
  • If you know lisp , you can expand its functionality
  • Some useful commands to get started:
    • C-h t get tutorial
    • C-g cancel command
    • C-x C-c quit emacs
    • C-h help

etags

• This helps you go to a function definition
  • Particularly useful in programs spanning multiple files
  • At the shell prompt, type
    • etags *.[ch]
  • In emacs
    • Choose visit tags from the C menu
      • Or ESC-x visit-tags-table
    • Subsequently, find tag from the menu, or ESC-., will take you to the function definition

Compiling in emacs

• Choose compile from the C menu
  • Or ESC-x compile
  • Errors and warnings will be printed on a sub- window
  • CTL-X ` will take you to the next error or warning

C compilers

• gcc, cc
• Using ANSI C, the code must pass with flags –Wall –ansi –pedantic with no warning messages
• See example1.c
  • How can we fix warning?
• Some examples
  • gcc –g –Wall –ansi –pedantic example1.c
  • gcc –g –c –Wall –ansi –pedantic example1.c
  • gcc –g example1.o
  • gcc –g example.o -lm

• run to run the program

Make

• make [-f makefile][option] target
  • A tool to update files derived from other files
  • The default files for make are ./makefile, ./Makefile, ./s.makefile
  • Use the –f option to specify some other file
    • make –f makefile
  • The makefile has three components
    • Macros: define constants
    • Target rules: Specify how targets are made
    • Inference rules: Specify how targets can be made, implicitly. make will first check if a target rule applies, before using inference rules.

make ... continued

• Inference rules
  • Target:
  • command
  • command
  • Target must be of the form .s1 or .s1.s2 where .s1 and .s must be prerequisites of the .SUFFIXES special target. - .s1.s2  make *.s2 from *.s - .s1  make * from *.s
  • Example: . c: $(CC) –o $@ $< .c.o: $(CC) –c $<

makefile examples

• See the example makefiles
  • makefile, makefile1, makefile
• makefile1 will recompile only the modified files, instead of everything
• makefile2 has inference rules
• www.cs.fsu.edu/cgi-bin/man.cgi can be used to find more information

Header files

• Usually define interfaces between separately compiled modules
• May contain macro definitions, preprocessor directives, declarations of types, and function prototypes
• Should not contain variable definitions or executable code

Some header file errors

• Improper header file use can cause problems
  • Try compiling example2.c
  • Including a header file multiple times may cause redefinition errors
  • Why does including stdio.h twice not cause any problem? - Look at /usr/include/stdio.h

Macros with and without Parameters

• #define MAX_LENGTH 256
  • ... for (i = 0; i < MAX_LENGTH; i++) ...
• Macros can have parameters
  • #define max(a,b) (a > b)? a : b
• What is wrong with the following?
  • #define sum(a, b) a + b
  • #define product(a, b) a*b
  • See example3.c, example3b.c, example3c.c, and example3d.c