COMP 110-001 Streams and File I/O Yi Hong June 10, 2015 Today - PowerPoint PPT Presentation

COMP 110-001  Streams and File I/O Yi Hong June 10, 2015

Today § Files, Directories, Path § Streams § Reading from a file § Writing to a file

Why Use Files for I/O? § RAM is not persistent § Data in a file remains after program execution, stored permanently

Working With Files § The data stored in these persistent storage are normally in the form of files § Have you tried to open a movie DVD in your computer using file explorer? § You will probably see  some folders and  files like this:

Working With Files § In short: • We often need to write the data to files to store it • We often need to read the data from files § We will cover some basics about files and directories in Windows / Linux & Mac OS first

Files and Directories § Files are stored in directories or folders in a tree structure § A directory can contain one  or more files and/or directories § The root directory in Windows is the drive name ( C: or D: , don’t miss the : ) § The root directory in Unix/ Linux/MacOS is /

Files and Directories: Path to File § A file is identified by its path through the file system, beginning from the root node • Linux/Unix: e.g., /home/yihong/Music • MacOS: e.g., /Users/yihong/Music • Windows: e.g., C:\Users\yihong\Music § The character used to separate the directory names (also called the delimiter ) is   forward slash (/) in Linux/Unix/MacOS, and backslash slash (\) in Windows.

Relative and Absolute Path § A path is either relative or absolute • An absolute path always contains the root element and the complete directory list required to locate the file • e.g.: /Users/yihong/Music § A relative path needs to be combined with another path in order to access a file • e.g. yihong/Music is a relative path • Without more information, a program cannot reliably locate the yihong/Music directory in the file system § In java, when you write a relative path, it’s relative to the working directory

�� Java’s Input/Output Mechanism § A stream is a flow of data into or out of a program Input stream Output stream Keyboard Monitor Input stream Output stream Compact disc Hard disk Program § Very complicated design based on “streams” § Here, we focus on how to use input and out streams

�� Text Files v.s. Binary Files § Text file: a sequence of characters § Binary file: pack values into binary representation A text f le . . . 1 2 3 4 5 - 4 2 7 8 0 A binary f le . . . 12345 -4072 8 § We only cover text file I/O in this course

COMP 110-001 Streams and File I/O Yi Hong June 10, 2015 Today - PowerPoint PPT Presentation

COMP 110-001 Streams and File I/O Yi Hong June 10, 2015 Today Files, Directories, Path Streams Reading from a file Writing to a file Why Use Files for I/O? RAM is not persistent Data in a file remains

Streams and File I/O Fundamentals of Computer Science Outline Overview of Streams and File

Files and Streams File Directories File Directory A set of files and other (sub)directories

File Manipulation in C Dalhousie University Winter 2019 Files and Streams Cs view of files

File output Ch 6 Highlights - text file output - text file input Download vs stream Streams

Objectives become familiar with the concept of an I/O stream Streams and File I/O

File output Ch 6 Download vs stream Streams A stream is information flow that is

File System Client and Server Server response (e.g., file block) request (e.g., read) Client

Ext 3/4 file systems Don Porter 1 COMP 790: OS Implementation Logical Diagram Binary Memory

CS 241 Data Organization File IO April 12, 2018 File Pointers Opening a file returns a

CS 10: Problem solving via Object Oriented Programming Streams Agenda 1. Streaming data 2.

File Systems: Fundamentals Don Porter Portions courtesy Emmett Witchel 1 COMP 530: Operating

Andrew Design Goals Transparent file naming in single name space Scalable -- O(1000s)

Streams In C, the term stream means any source of input or any destination for output.

Encrypted File Systems Don Porter 1 COMP 790: OS Implementation Goals Protect

File Streams and File I/O http://cs.mst.edu Stream Operators Insertion Operator

COMP 364: Computer Tools for Life Sciences Python programming: File IO Christopher J.F. Cameron

Programming II Spring 2018 Streams and Input/Output 1 Today Streams and Files

COMP 2718: The File System: Part 1 By: Dr. Andrew Vardy Adapted from the notes of Dr. Rod Byrne

File Systems: Fundamentals A named collection of related information recorded on secondary

Lecture 9: files and streams Files open(filename, mode) returns a file object filename is a path

CSE 143 Streams as C++ Classes Streams are C++ classes Streams have lots of built-in

COMP MPANY ANY PROFILE FILE Informa rmati tion on as as a at YE14 14 To be A Leading

Google is Really Different. The Dalles, OR (2006) Huge Datacenters in 25+ Worldwide

Linux Kernel Synchronization System Calls Synchronization in Kernel the kernel RCU File