CS 214 / Intro
==============

Systems Programming

Prof. David Menendez <davemm@cs.rutgers.edu>
    Please put [CS214] in the subject line
    Please use the discussion tab in Canvas for course questions
    
    Office hours: Hill 448, schedule pending

Recitations should start next week
(Please look for an announcement)

Systems programming: what is it?

- Language run-time systems
    e.g., standard library features (file IO, memory allocation, etc.)
    
- operating systems (OS)
    - shared implementation of common features
    - management of shared resources
        - protect programs from other programs
        - protect users from other users
        - maintain abstractions
    - common utilities and user interface


C programming language
Unix-style operating systems (Linux, MacOS, *BSD, etc.)
    - file IO
    - file systems
    - multitasking, process control
    - network communication (sockets)
    - multithreading (pthread)
    
Project-oriented class
    three or four large programming assignments
    these are two-person assignments
    why?
        - most of you will need to work with others in the future
        - future classes will involve larger group projects
        - opportunity to work with others
        
    tips
        - be very clear about who you are working with
        - communicate
        - determine clear goals and responsibilities
        - don't wait until the last few days to see what the other person wrote
        
Reference compiler GCC 13
Reference environment is the Instructional Lab (iLab)


Why C?
------

C is a relatively simple language
    - gives good visibility to the hardware and OS features
    - designed to run (and be run) on low-powered hardware

C vs Java
    - similar syntax
    - similar orientation
    
Java is interpreted
    java source code  -- javac --> "byte code"  
    MyClass.java                MyClass.class
    
    requires another program (java) to execute the byte code

C is compiled
    C source code  -- gcc -> executable
    myprogram.c              myprogram


    C source code -- gcc -> unlinked machine code -- ld --> executable
    myprogram.c             myprogram.o                     myprogram


    compiler translates source code to machine code
        source code - human-readable text
        machine code - binary format understood by the CPU


Compiling programs with gcc

gcc hello.c

    compile source file "hello.c", link with standard library,
    produce executable called "a.out"
    
gcc hello.c -o hello
gcc -o hello hello.c

    compile source file "hello.c", link with standard library,
    produce executable called "hello"
    

gcc main.c support.c mymalloc.c -o prog

    compile 3 source files, link together along with standard library,
    produce executable called "prog"


gcc -c hello.c
gcc hello.c -c

    compile "hello.c", produce unlinked object file "hello.o"
    
gcc main.o support.o mymalloc.o -o prog
    links 3 object files together with standard library,
    produce executable called "prog"
    
recommended options

-Wall   enables the most useful warnings

-std=c99    enforce usage of 1999 C standard

-g          inserts information for the debugger

-fsanitize=address
            inserts AddressSanitizer into your executable