一、目录介绍

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?
We know what you’re thinking
We know what your brain is thinking
Metacognition: thinking about thinking
Here’s what WE did
Here’s 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
But what does a complete C program look like?
But how do you run the program?
Two types of command
Here’s the code so far
Card counting? In C?
There’s more to booleans than equals…
What’s the code like now?
Pulling the ol’ switcheroo
Sometimes once is not enough…
Loops often follow the same structure…
You use break to break out…
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 sou’east, Cap’n
Try passing a pointer to the variable
Using memory pointers
How do you pass a string to a function?
Array variables are like pointers…
What the computer thinks when it runs your code
But array variables aren’t quite pointers
Why arrays really start at 0
Why pointers have types
Using pointers for data entry
Be careful with scanf()
fgets() is an alternative to scanf()
Anyone for three-card monte?
Oops…there’s a memory problem…
String literals can never be updated
If you’re 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 the strstr() function
It’s time for a code review
Array of arrays vs. array of pointers
Your C Toolbox
View Sample
3. Creating Small Tools: Do one thing and do it well
View Sample
Small tools can solve big problems
View Sample
Here’s how the program should work
View Sample
But you’re not using files…
View Sample
You can use redirection
View Sample
You can redirect the Standard Input with <…
View Sample
…and redirect the Standard Output with >
View Sample
But there’s a problem with some of the data…
View Sample
Introducing the Standard Error
View Sample
By default, the Standard Error is sent to the display
View Sample
fprintf() prints to a data stream
View Sample
Let’s update the code to use fprintf()
View Sample
Small tools are flexible
View Sample
Don’t change the geo2json tool
View Sample
A different task needs a different tool
View Sample
Connect your input and output with a pipe
View Sample
The bermuda tool
View Sample
But what if you want to output to more than one file?
View Sample
Roll your own data streams
View Sample
There’s more to main()
View Sample
Overheard at the Head First Pizzeria
View Sample
Let the library do the work for you
View Sample
Your C Toolbox
4. Using Multiple Source Files: Break it down, build it up
Don’t put something big into something small
Use casting to put floats into whole numbers
Oh no…it’s the out-of-work actors…
Let’s see what’s happened to the code
Compilers don’t like surprises
Split the declaration from the definition
Creating your first header file
If you have common features…
You can split the code into separate files
Compilation behind the scenes
The shared code needs its own header file
It’s not rocket science…or is it?
Don’t recompile every file
First, compile the source into object files
It’s hard to keep track of the files
Automate your builds with the make tool
How make works
Tell make about your code with a makefile
Your C Toolbox
C Lab 1: Arduino
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 struct’s 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?
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…
Inserting values into the list
Use the heap for dynamic storage
Give the memory back when you’re done
Ask for memory with malloc()…
Oh, no! It’s the out-of-work actors…
Let’s fix the code using the strdup() function
Free the memory when you’re done
Exhibit A: the source code
An overview of the SPIES system
Software forensics: using valgrind
Use valgrind repeatedly to gather more evidence
Look at the evidence
The fix on trial
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 there’s no 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
Make your functions streeeeeetchy
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…
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…
Dynamic linking happens at runtime
Can you link .a at runtime?
First, create an object file
What you call your dynamic library depends on your platform
Your C Toolbox
C Lab 2: OpenCV
9. Processes and System Calls: Breaking boundaries
System calls are your hotline to the OS
Then someone busted into the system…
Security’s not the only problem
The exec() functions give you more control
There are many exec() functions
The array functions: execv(), execvp(), execve()
Passing environment variables
Most system calls go wrong in the same way
Read the news with RSS
exec() is the end of the line for your program
Running a child process with fork() + exec()
Your C Toolbox
10. Interprocess Communication: It’s good to talk
Redirecting input and output
A look inside a typical process
Redirection just replaces data streams
fileno() tells you the descriptor
Sometimes you need to wait…
Stay in touch with your child
Connect your processes with pipes
Case study: opening stories in a browser
In the child
In the parent
Opening a web page in a browser
The death of a process
Catching signals and running your own code
sigactions are registered with sigaction()
Rewriting the code to use a signal handler
Use kill to send signals
Sending your code a wake-up call
Your C Toolbox
11. Sockets and Networking: There’s no place like 127.0.0.1
The Internet knock-knock server
Knock-knock server overview
BLAB: how servers talk to the Internet
A socket’s not your typical data stream
Sometimes the server doesn’t start properly
Why your mom always told you to check for errors
Reading from the client
The server can only talk to one person at a time
You can fork() a process for each client
Writing a web client
Clients are in charge
Create a socket for an IP address
getaddrinfo() gets addresses for domains
Your C Toolbox
12. Threads: It’s 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
A. Leftovers: The top ten things (we didn’t cover)
1. Operators
2. Preprocessor directives
3. The static keyword
4. How big stuff is
5. Automated testing
6. More on gcc
7. More on make
8. Development tools
9. Creating GUIs
10. Reference material
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