C021TV-I1-S4.

Présentation au sujet: "C021TV-I1-S4."— Transcription de la présentation:

1 C021TV-I1-S4

2 ICN : 1. Binary coding 1. Representation of information in the form of bits 2. Storing images or sounds 3. Compression 4. Data organization 5. Databases Introduction de la semaine 2/2 Présentation du sommaire global de la semaine : apparition progressive des éléments de la liste, puis mise en évidence de la portion concernée par la vidéo. Mise en évidence = police noire + gras Nom abrégé de cours - Enseignant

3 Understanding coding Data stored on a hard disk,
or transferred on the network Whatever the content The computer that reads or generates should know how they are coded Header indicating their size, duration, color, compression type, … The header specifies the data coding The computer should know how to decode the header

4 Data basic types Smaller or bigger whole numbers (8, 16, 32, 64bits)
Eventually negative ones Floating point numbers 1, *1023 Smaller or bigger The programmer chooses accordingly to the possible values it has to store Age, month, temperature, level of gray, …

5 More complex data How to store a date (22/11/2016) or a color (RGB)?
Combination of several numbers Tuples (Structure, Monitoring, …) A date is made with 3 whole numbers (day, month, year) A period is made with 2 dates (start, end) A picture is made up of pixels, formed by 3 colors

6 Advanced data types Sometimes, the amount of data to manipulate is unknown beforehand How many guests at a party? How many stages on a journey? Chart Similar structure elements, numbered N° Name Date of Birth Height (m) 1 Joe 21/02/1869 1,6 2 Jack 15/06/1868 1,7 3 William 02/03/1867 1,8 4 Averell 09/11/1866 1,9

7 Advanced data types Sometimes, the amount of data to manipulate is unknown beforehand How many guests at a party? How many stages on a journey? List Similar structure elements, pointing towards the next one in the list Bordeaux 15/11 17/11 Paris 20/11 21/11 Rennes 18/11 19/11

8 Representation of data in the memory
Concretely, how is data distributed? Which order? What size? Described by the programmer when writing the program Or in the file format specs A GIF file begins with GIF89a then the width and the height of the image on 16 bits each, etc. Jour Mois Precise organization of different data should be clearly specified Année Representer toutes ces données dans la mémoire de l’ordinateur ou dans un fichier Soit convention hardcodée dans le programme par le langage de prog pour lire/écrire Soit le programme a été ecrit pour format spécifique et on est sur que les données arriveront dans ce format Soit entete detaillant l’organisation (comme dans fichier) Format entete specifié permet de le decoder pour ensuite decoder les données Nom abrégé de cours - Enseignant

9 Keep in mind Data is made up of basic elements
Whole and floating-point numbers, letters, … That can be assembled to represent complex objects Tuples, charts, lists, … The assembly should be specified to be able to be used