data structures and algorithms lab1

DATA STRUCTURES AND ALGORITHMS

LAB 1

Bianca Tesila

FILS, Feb 2014

COURSE INFO

Lectures: Maria-Iuliana Dascalu mariaiuliana.dascalu@gmail.com http://mariaiulianadascalu.com/ (where you

can find the courses)

Labs: Bianca Tesila bianca.tesila@gmail.com http://biancatesila.wordpress.com/ (labs,

grades, home assignments)

GRADING

Exam: 40p Tests & presence at the course: 10p Labs & Assignments: 50p

Assignments: 30p ( 3 x 10p) Lab Activity: 20p ( presence, class assignments,

small home assignments)

Rules:• Minimum 45p in order to pass • Minimum 25p out of 60p in order to take the

exam• One should attend at least 10 labs(out of 12)

TOOLS & USEFUL LINKS

C-Free 5.0 Standard (http://www.programarts.com/cfree_en/download.htm)

Any other IDE or compiler for C/C++ (ex. GCC under Linux)

http://www.cs.usfca.edu/~galles/visualization/Algorithms.html (it helps you understand how various data structures work)

OBJECTIVES

run and compile C programs identify the structure of a C program use standard I/O operations define variables declare and implement functions make structures

INTRODUCTION TO C PROGRAMMING The basic structure of a C program:

Inclusion of headers Definition of types/classes Declaration of global variables Definition of functions The main function

Similarities to the structure of a Java program: Inclusion of headers is similar to importing packages or

classes Differences from the structure of a Java program:

Functions and variables may also be defined outside of a class The main function is not part of a class Arrays can also be allocated statically in C/C++

A C program is written in a file with the “.c” extension: the source code

After compilation, another file, with the “.o” extension appears: the object code.

After execution, another file, with the “.exe” extension appears: the executable

INTRODUCTION TO C PROGRAMMING

EXAMPLE OF A C PROGRAM:

#include <stdio.h> // inclusion of the stdio.h header

int a, b, c; // global variables of the type int: a, b, c

int main() { // beginning of the main functiona = 10;scanf("%d", &b); // read the value of b from the standard input

c = a + b; // assign the sum of a and b to the variable cprintf("%d\n", c); // print the value of c to the standard output

return 0; // finish the main function successfully}

Pay attention: C is case-sensitive!

I/O OPERATIONS: STANDARD OUTPUT OPERATIONS

We shall use the printf function: printf(format, param_1, param_2, …, param_n);

format = a string containing characters and format specifiers param_1, param_2, …, param_n = expressions; their values are written

taking into account the corresponding format specifier

Format Specifier Type

%i or %d int

%ld long

%f float

%lf double

%c char

%s string

I/O OPERATIONS: STANDARD OUTPUT OPERATIONS

‼ Exercise: run the below example and see how each format specifier works

#include <stdio.h>int main() {

printf("%d\n", 7);printf("%3d\n", 7);printf("%03d\n", 7);printf("%3.2f\n", 5.1);printf("%.2f\n", 4.245);printf("%s\n", "blue");return 0;

}

Note: we used a special character /n (newline character)

The \n used in the printf statements is called an escape sequence. Commonly used escape sequences are:

\n (newline) \t (tab) \v (vertical tab) \f (new page) \b (backspace) \r (carriage return) \n (newline)

I/O OPERATIONS: STANDARD INPUT OPERATIONS

We shall use the scanf function:

scanf(format, param_1, param_2, …, param_n);

format = a string containing characters and format specifiers param_1, param_2, …, param_n = expressions; their values are stored

taking into account the corresponding format specifier

Similar to printf Use «stdio.h»  for I/O operations

I/O OPERATIONS: STANDARD INPUT OPERATIONS

#include <stdio.h> int main () {

char name [80]; int age; printf ("Enter your family name: "); scanf ("%s",name); printf ("Enter your age: "); scanf ("%d", &age); printf ("Mr. %s , %d years old.\n“, name,

age); return 0;

}

I/O OPERATIONS

‼Exercise: Write a program to calculate  the average of two float numbers. The result shall be displayed with 2 decimals. Use scanf and printf!

Hint: %.2f   -> format specifier for float with 2 decimals

I HOPE YOU’RE NOT SLEEPING YET

FUNCTIONS: DECLARATION AND IMPLEMENTATION

The general form of a function definition in C programming language is as it follows:

return_type function_name( parameter list ) { body of the function

}

Visibility domain: local vs. global variables Parameter passing: by-value

FUNCTIONS: EXAMPLE

• Note the use of math.h library: for sqrt function (the same meaning as in Java)

• Note the control flow structures (if, if-else, for, …)

• Note the function definition and call: the implemented function calculates if a number is prime or not

FUNCTIONS

‼Exercise: Check whether a number is a palindrome or not.

Hint: a palindrome is a number that remains the same when its digits are reversed.

333 is a palindrome123 is not a palindrome

STRUCTURES

struct struct_name { variables (fields of the struct type)}

Like Java classes but without methods or public/private specifications

Used to package related data together

User-defined collection of one or more variables (fields), grouped under one name

The members of a structure are accessed with “.”

STRUCTURES: EXAMPLE

struct date {

unsigned int day;

unsigned int month;

unsigned long year;

char name_day[3];

char name_month[4];

};

typedef struct date date;

date today;

‼ date is now a type

typedef struct date {

unsigned int day;

unsigned int month;

unsigned long year;

char name_day[3];

char name_month[4];

} date;

date today;

‼ typedef allows you to declare instances of a struct without using keyword "struct"

STRUCTURES: EXAMPLE

void writeDDMMMYYYY(date myDate){

printf("%2d %s %4d ", myDate.day,myDate.name_month, myDate.year);

}

STRUCTURES

‼ Exercise: Design a structure  for representing dates and write functions that:

       - Check if a variable value of the structure is a valid date       - Calculate the next date of a given date       - Calculate the date before a given date

HOMEWORK Finish all the lab exercises. Write a program that displays the first ten Fibonacci

numbers. Write a program to simulate the Bulls and Cows game(http://

en.wikipedia.org/wiki/Bulls_and_cows), by giving two input numbers.

Write functions for writing, reading, addition and multiplication of rare polynomials.

Rare polynomials with integer coefficients are polynomials of large degrees and many coefficients equal to 0. They can be represented by a data structure defined as:

typedef struct TMonom{  int coefficient;  unsigned int exponent;}TMonom;

TMonom[50] polynomial;