Overview

C and Data StructuresBaojian Hua

bjhua@ustc.edu.cn

What is this course about?

Key elements of C programming: C is the most widely-used system

language Linux, Windows, network server, compiler, …

C is low-level Device driver, embedded (real-time) system, … Closely related with architectures

Motivating ideas for other languages C++/Java/C# etc.

What is this course about? Data structures design and impl’

Specific topics include: List, array, stack, queue, tree, graph, hash, so

rting, searching, etc. General principals in designing and analy

zing data structures Tradeoffs between space and time Efficiency and clarity, etc.

Design new data structures!

What’s the goal of this course? Knowledge preparation

C and data structures are crucial for CS Foundations for later computer courses

Familiarize you with computer thinking e.g.: abstraction (ADT), recursion

Improve your programming skills More experience in programming Emphasis on modularity, ADT, and clarity

Administrivia Instructor: Hua, Baojian

bjhua@ustc.edu.cn Office hour: at every class, or to appoint

TA: Xi, Jing 68839304 jingxi@ustc.edu.cn 304, Mingde building

Course Home Page Home page http://staff.ustc.edu.cn/~bjhua/cou

rses/summer10 Course administrivia Lecture notes Programming assignments Software Test and evaluation

Check course home page everyday

Textbooks and References The C Programming Language (Second Edition) . K

ernighan and Ritchie, 1988. C: A Reference Manual, Harbison and Steele, 2002. The Practice of Programming, Kernighan and Pike,

1999. Programming with GNU Software, Loukides and Or

am, 1997. Fundamentals of data structures in C. Ellis Horowit

z et al. 2006. Algorithm in C. Rdbert Sedgewick. Addison-Wesley

Professional; 3 edition. 1997.

Labs There are 5 labs (tentative)

Each consists of some required problems and optional problems (Optional)

Optional assignments are not required, but highly recommended

Solve them independently Late homework should only be

considered under extraordinary circumstances

Submit to Xi, Jing

Labs

This year we use gcc a Windows nice IDE call CodeBlocks Version 4.1 of gcc, compiles C99

In another year, we used Microsoft’s Visual Studio, but… :-( So if you’d like to use other compilers, c

ome to talk with us in advance

Test and Evaluation

There is a final test: Close book Cover all materials in the course Evaluation: 50% labs + 50% test Be concerned

this course is more profitable and illuminating (and exciting) than you may assume

Any questions before we start?

What are programming languages? Machines only understand “01”

so we must program with “01”? but early programmers do this! (crazy!)

Program languages offer a high-level view of computer another level of indirection, more and more abstract

Software toolchain helps to do the mapping

The C Programming Language

Capsule history: BCPL B C K&R C ANSI C C99 1960 1970 1972 1978 1988 LISP Smalltalk C++

Java 1960’s 1970’s 1980’s

1994C#

2000

The C Programming Language C is a system programming language

Originally used to write Unix and later Linux and Windows

Data types and control structures close to most machines

So you know system deeper, you can program better

Pros and cons: Can do whatever you want: flexible and

powerful Can do whatever you do NOT want: shoot

yourself in the foot

First Programint main ()

{

return 0;

}

// 1. Compile

// 2. run

// 3. OS takes over, and runs it on machine

// 4. your program runs

// 5. return back to OS

// 6. finished!

Why the name is “main”?

Why “0”?

A bit more#include <stdio.h>

int main ()

{

printf(“hello, world\n”);

return 0;

}

What’s “stdio.h”?And where is it?

What’s “#include”?

What’s “printf” doing?Why bother to use it?

Variables and Arithmetic Expressions

Print the table of Fahrenheit temperatures and their centigrade or Celsius equivalents:

C=(5/9)*(F-32)

F: C:0 -17 20 -6 40 4 60 15 80 26 100 37 120 48 140 60 160 71 180 82 200 93

Program#include <stdio.h> int main() { int f, c; f = 0; c = 5 * (f-32) / 9; printf("%d\t%d\n", f, c);

return 0;}

F: C:0 -17 20 -6 40 4 60 15 80 26 100 37 120 48 140 60 160 71 180 82 200 93

Program#include <stdio.h> int main() { int f, c; for (f=0; f<=200; f+=20) { c = 5 * (f-32) / 9; printf("%d\t%d\n", f, c); } return 0;}

F: C:0 -17 20 -6 40 4 60 15 80 26 100 37 120 48 140 60 160 71 180 82 200 93

Data Types In C, the key word “int” stands for in

teger types Its range depends on the machine, typical

16 or 32 bits C provides other data types:

char single character, 8 bits ‘a’, ‘8’

long long integers, 32 bits 333L

float 32 bits 3.14f

double float numbers, 64 bits 3.14

Assignment

Assignment statement: x=e; x is a variable, and e is an expression Meaning: set x the value of e Ex:

f = 0; c = 5 * (f - 32) / 9;

For Statement#include <stdio.h>

int main() { int f, c; for (f=0; f<=200; f+=20) {

c = 5 * (f-32) / 9; printf ("%d\t%d\n", f, c); }

return 0;}

f=0;

f<=200

f +=20;

…;

More on printfprintf ("%d\t%d\n", f, c);

Format string: Control how the data to output %d means output an integer See the text for a complete list and their meanin

gs Escape character:

‘\t’, ‘\n’ It’s one of the so-called IO functions

More on this later

Function A function in C, is just like:

subroutine in Fortran procedure or function in Pascal methods in Java or C#

A function provides a convenient way to: encapsulate information modularize system (along with others) reuse code

Example// calculate circle area, #1 try#include <stdio.h>int main(){ double area; int r; r = 5; area = 3.14 * r * r; printf (“%lf\n”, area);

return 0;}

Or#include <stdio.h>

int main(){ double area; int r; for (r = 0; r<10; r++) { area = 3.14 * r * r; printf (“%lf\n”, area); }

return 0;}

Problem #1:Code Duplication// calculate circle area, 1st tryint main(){ double area; int r;

for (r = 0; r<10; r++) area = 3.14 * r * r;

for (r = 10; r<20; r++) area = 3.14 * r * r;

return 0;}

Problem #2:Hard to Maintain// calculate circle area, 1st tryint main(){ double area; int r;

// Say, want to change to 3.1415926for (r = 0; r<10; r++)

area = 3.14 * r * r;

for (r = 10; r<20; r++) area = 3.14 * r * r;

return 0;}

Problem #3:Client Transparent// calculate circle area, 1st tryint main(){ double area; int r;

// We really don’t want to know this …for (r = 0; r<10; r++)

area = 3.14 * r * r;

for (r = 10; r<20; r++) area = 3.14 * r * r;

return 0;}

Summary So Far Code duplication

Same code anywhere remember: good programmers are

lazy Hard to maintain and evolve

Must touch all parts of a big entity Client Transparent

Essentially, we want the interface, not the implementation details

Using Functiondouble area (int r);

double area (int r){ double pi = 3.14; return (pi*r*r);}

int main(){ double a; int r; for (r=0; r<10; r++) a = area(r); return 0;}

function prototype

function definition

function body, as we have discussed for main()

implicit conversion

function call with argument r

Function Summary Function prototype:return-type function-name (parameter

declarations, if any) ; Function definition:return-type function-name (parameter

declarations, if any) {

declarations statements

} Function call:function-name (expressions, if any);

Call-by-valuevoid foo (int n);void foo (int n){ n--; return;}

int main (){ int n = 9; foo (n); printf (“%d\n”, n); return 0;}

decrement operation, n=n-1

type void, no value

the value of n?

9

9

8