Head First C. A Brain-Friendly Guide

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• Head First C
• Dedication
• Advance Praise for Head First C
• Praise for other Head First books
• Authors of Head First C
• How to use this Book: Intro
  • Who is this book for?
    • Who should probably back away from this book?
  • We know what youre thinking
  • We know what your brain is thinking
  • Metacognition: thinking about thinking
  • Heres what WE did
  • Heres what YOU can do to bend your brain into submission
  • Read me
  • The technical review team
  • Acknowledgments
  • Safari Books Online
• 1. Getting Started with C: Diving in
  • C is a language for small, fast programs
    • The way C works
  • But what does a complete C program look like?
  • But how do you run the program?
    • The program works!
  • Two types of command
    • Do something
    • Do something only if something is true
  • Heres the code so far
  • Card counting? In C?
  • Theres more to booleans than equals...
    • && checks if two conditions are true
    • II checks if one of two conditions is true
    • ! flips the value of a condition
  • Whats the code like now?
  • Pulling the ol switcheroo
  • Sometimes once is not enough...
    • Using while loops in C
  • Loops often follow the same structure...
    • ...and the for loop makes this easy
  • You use break to break out...
    • ...and continue to continue
  • Your C Toolbox
• 2. Memory and Pointers: What are you pointing at?
  • C code includes pointers
  • Digging into memory
  • Set sail with pointers
  • Set sail soueast, Capn
  • Try passing a pointer to the variable
    • Pointers make it easier to share memory
  • Using memory pointers
  • How do you pass a string to a function?
    • Honey, who shrank the string?
  • Array variables are like pointers...
    • ...so our function was passed a pointer
  • What the computer thinks when it runs your code
  • But array variables arent quite pointers
  • Why arrays really start at 0
  • Why pointers have types
  • Using pointers for data entry
    • Entering numbers with scanf()
  • Be careful with scanf()
    • scanf() can cause buffer overflows
  • fgets() is an alternative to scanf()
    • Using sizeof with fgets()
  • Anyone for three-card monte?
  • Oops...theres a memory problem...
  • String literals can never be updated
  • If youre going to change a string, make a copy
  • Memory memorizer
  • Your C Toolbox
• 2.5. Strings: String theory
  • Desperately seeking Susan Frank
  • Create an array of arrays
  • Find strings containing the search text
    • Using string.h
  • Using the strstr() function
  • Its time for a code review
  • Array of arrays vs. array of pointers
  • Your C Toolbox
• 3. Creating Small Tools: Do one thing and do it well
  • Small tools can solve big problems
  • Heres how the program should work
  • But youre not using files...
  • You can use redirection
  • You can redirect the Standard Input with <...
  • ...and redirect the Standard Output with >
  • But theres a problem with some of the data...
  • Introducing the Standard Error
  • By default, the Standard Error is sent to the display
  • fprintf() prints to a data stream
  • Lets update the code to use fprintf()
  • Small tools are flexible
  • Dont change the geo2json tool
  • A different task needs a different tool
  • Connect your input and output with a pipe
  • The bermuda tool
  • But what if you want to output to more than one file?
  • Roll your own data streams
    • The program runs, but...
  • Theres more to main()
  • Overheard at the Head First Pizzeria
  • Let the library do the work for you
  • Your C Toolbox
• 4. Using Multiple Source Files: Break it down, build it up
  • Dont put something big into something small
  • Use casting to put floats into whole numbers
  • Oh no...its the out-of-work actors...
  • Lets see whats happened to the code
  • Compilers dont like surprises
    • Fixing function order is a pain
    • In some situations, there is no correct order
  • Split the declaration from the definition
  • Creating your first header file
  • If you have common features...
    • ...its good to share code
  • You can split the code into separate files
  • Compilation behind the scenes
  • The shared code needs its own header file
    • Include encrypt.h in your program
  • Its not rocket science...or is it?
  • Dont recompile every file
    • Save copies of the compiled code
  • First, compile the source into object files
    • Then, link them together
  • Its hard to keep track of the files
  • Automate your builds with the make tool
    • What does make need to know?
  • How make works
  • Tell make about your code with a makefile
  • Your C Toolbox
  • C Lab 1: Arduino
    • The spec: make your houseplant talk
      • The physical device
      • The Arduino
      • The Arduino IDE
    • Build the physical device
      • Build the moisture sensor
      • Connect the LED
      • Connect the moisture sensor
    • Heres what your code should do
      • Read from the moisture sensor
      • Write to the LED
      • Write to the serial port
      • Heres what your C code should look like
    • Here are some useful Arduino functions
    • The finished product
• 5. Structs, Unions, and Bitfields: Roll your own structures
  • Sometimes you need to hand around a lot of data
  • Cubicle conversation
  • Create your own structured data types with a struct
  • Just give them the fish
  • Read a structs fields with the . operator
  • Can you put one struct inside another?
  • How do you update a struct?
  • The code is cloning the turtle
  • You need a pointer to the struct
  • (*t).age vs. *t.age
  • Sometimes the same type of thing needs different types of data
  • A union lets you reuse memory space
  • How do you use a union?
    • C89 style for the first field
    • Designated initializers set other values
    • Set the value with dot notation
    • unions are often used with structs
  • An enum variable stores a symbol
  • Sometimes you want control at the bit level
  • Bitfields store a custom number of bits
  • Your C Toolbox
• 6. Data Structures and Dynamic Memory: Building bridges
  • Do you need flexible storage?
  • Linked lists are like chains of data
  • Linked lists allow inserts
  • Create a recursive structure
  • Create islands in C...
    • ...and link them together to form a tour
  • Inserting values into the list
  • Use the heap for dynamic storage
    • First, get your memory with malloc()
  • Give the memory back when youre done
    • Free memory by calling the free() function
  • Ask for memory with malloc()...
    • ...and free up the memory with free()
  • Oh, no! Its the out-of-work actors...
  • Lets fix the code using the strdup() function
    • So does it fix the code?
  • Free the memory when youre done
  • Exhibit A: the source code
  • An overview of the SPIES system
    • The program builds a tree of suspects
  • Software forensics: using valgrind
    • Prepare your code: add debug info
    • Just the facts: interrogate your code
  • Use valgrind repeatedly to gather more evidence
    • This time, valgrind found a memory leak
  • Look at the evidence
    • 1. Location
    • 2. Clues from valgrind
  • The fix on trial
    • The leak is fixed
  • Your C Toolbox
• 7. Advanced Functions: Turn your functions up to 11
  • Looking for Mr. Right...
  • Pass code to a function
  • You need to tell find() the name of a function
  • Every function name is a pointer to the function...
  • ...but theres no function data type
    • Why doesnt C have a function data type?
  • How to create function pointers
  • Get it sorted with the C Standard Library
  • Use function pointers to set the order
  • Automating the Dear John letters
  • Create an array of function pointers
    • But how does an array help?
  • Make your functions streeeeeetchy
    • So how can YOU do that?
  • Your C Toolbox
• 8. Static and Dynamic Libraries: Hot-swappable code
  • Code you can take to the bank
  • Angle brackets are for standard headers
  • But what if you want to share code?
  • Sharing .h header files
  • Share .o object files by using the full pathname
  • An archive contains .o files
  • Create an archive with the ar command...
    • ...then store the .a in a library directory
  • Finally, compile your other programs
  • The Head First Gym is going global
  • Calculating calories
  • But things are a bit more complex...
  • Programs are made out of lots of pieces...
    • ...but once theyre linked, you cant change them
  • Dynamic linking happens at runtime
  • Can you link .a at runtime?
    • Dynamic libraries are object files on steroids
  • First, create an object file
  • What you call your dynamic library depends on your platform
    • Compiling the elliptical program
  • Your C Toolbox
  • C Lab 2: OpenCV
    • The spec: turn your computer into an intruder detector
      • The intruder detector
      • OpenCV
      • Installing OpenCV
    • What your code should do
      • Take input from your computer camera
      • Grab an image from the webcam
      • Detect an intruder
      • Make a clean getaway
      • Optional: show the current webcam output
    • The finished product
    • Its time to become a C ninja...
• 9. Processes and System Calls: Breaking boundaries
  • System calls are your hotline to the OS
  • Then someone busted into the system...
  • Securitys not the only problem
  • The exec() functions give you more control
    • exec() functions replace the current process
  • There are many exec() functions
    • The list functions: execl(), execlp(), execle()
  • The array functions: execv(), execvp(), execve()
  • Passing environment variables
    • But what if theres a problem?
  • Most system calls go wrong in the same way
  • Read the news with RSS
  • exec() is the end of the line for your program
    • fork() will clone your process
  • Running a child process with fork() + exec()
    • 1. Make a copy
    • 2. If youre the child process, call exec()
  • Your C Toolbox
• 10. Interprocess Communication: Its good to talk
  • Redirecting input and output
  • A look inside a typical process
  • Redirection just replaces data streams
    • Processes can redirect themselves
  • fileno() tells you the descriptor
    • dup2() duplicates data streams
  • Sometimes you need to wait...
    • The waitpid() function
  • Stay in touch with your child
    • Reading story links from rssgossip
  • Connect your processes with pipes
    • Piped commands are parents and children
  • Case study: opening stories in a browser
    • pipe() opens two data streams
  • In the child
  • In the parent
  • Opening a web page in a browser
  • The death of a process
    • The O/S controls your program with signals
  • Catching signals and running your own code
    • A sigaction is a function wrapper
    • All handlers take signal arguments
  • sigactions are registered with sigaction()
  • Rewriting the code to use a signal handler
  • Use kill to send signals
    • Send signals with raise()
  • Sending your code a wake-up call
    • ...the timer fires a SIGALRM signal
  • Your C Toolbox
• 11. Sockets and Networking: Theres no place like 127.0.0.1
  • The Internet knock-knock server
  • Knock-knock server overview
  • BLAB: how servers talk to the Internet
    • 1. Bind to a port
    • 2. Listen
    • 3. Accept a connection
  • A sockets not your typical data stream
  • Sometimes the server doesnt start properly
  • Why your mom always told you to check for errors
    • Bound ports are sticky
  • Reading from the client
  • The server can only talk to one person at a time
  • You can fork() a process for each client
    • The parent and child use different sockets
  • Writing a web client
  • Clients are in charge
    • Remote ports and IP addresses
  • Create a socket for an IP address
  • getaddrinfo() gets addresses for domains
    • Create a socket for a domain name
  • Your C Toolbox
• 12. Threads: Its a parallel world
  • Tasks are sequential...or not...
  • ...and processes are not always the answer
  • Simple processes do one thing at a time
  • Employ extra staff: use threads
  • How do you create threads?
  • Create threads with pthread_create
  • The code is not thread-safe
  • You need to add traffic signals
  • Use a mutex as a traffic signal
  • Your C Toolbox
  • C Lab 3: Blasteroids
    • Write the arcade game Blasteroids
    • Your mission: blast the asteroids without getting hit
    • Allegro
      • Installing Allegro
      • You may need CMake
    • What does Allegro do for you?
    • Building the game
    • The spaceship
      • What the spaceship looks like
      • Collisions
      • Spaceship behavior
      • Reading keypresses
    • The blast
      • Blast appearance
      • Blast behavior
    • The asteroid
      • Asteroid appearance
      • How the asteroid moves
      • When the asteroid is hit by a blast
    • The game status
    • Use transformations to move things around
    • The finished product
    • Leaving town...
    • Its been great having you here in Cville!
• A. Leftovers: The top ten things (we didnt cover)
  • #1. Operators
    • Increments and decrements
    • The ternary operator
    • Bit twiddling
    • Commas to separate expressions
  • #2. Preprocessor directives
    • Conditions
  • #3. The static keyword
    • static can also make things private
  • #4. How big stuff is
  • #5. Automated testing
  • #6. More on gcc
    • Optimization
    • Warnings
  • #7. More on make
    • Variables
    • Using %, ^, and @
    • Implicit rules
  • #8. Development tools
    • gdb
    • gprof
    • gcov
  • #9. Creating GUIs
    • Linux GTK
    • Windows
    • The Mac Carbon
  • #10. Reference material
    • Websites
• B. C Topics: Revision roundup
  • Basics
  • Pointers and memory
  • Strings
  • Data streams
  • Data types
  • Multiple files
  • Structs
  • Unions and bitfields
  • Data structures
  • Dynamic memory
  • Advanced functions
  • Static and dynamic libraries
  • Processes and communication
  • Sockets and networking
  • Threads
• Index
• About the Authors
• Copyright

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