Topic 8: I/O. Reading: Chapter 7 in Kernighan & Ritchie more details in Appendix B (optional) even more details in GNU C Library manual (optional)
|
|
- Elizabeth Fletcher
- 5 years ago
- Views:
Transcription
1 Topic 8: I/O Reading: Chapter 7 in Kernighan & Ritchie more details in Appendix B (optional) even more details in GNU C Library manual (optional) No C language primitives for I/O; all done via function calls. 1
2 Small Digression: C Library vs. System Calls System calls: functions provided with the Linux kernel, so that other programs may access system functionality. C Library includes access to these system calls. Also provides higher-level functions written for use in C programs. This topic: I/O using higher-level text-oriented C library functions defined in <stdio.h>. Also available: low-level I/O using system calls directly to read & write in binary format. 2
3 Example: Opening a Files To read from or write to a file (other than standard input/output): Need a "file pointer" type FILE *. To create a file pointer from a file name: FILE *fp = fopen(name, mode); File name: a string -- absolute or relative file name Mode: a string saying how the file will be used "r" = read "w" = write "a" = append In case of error: fopen returns NULL. 3
4 Reacting To Errors Goals for a useful program/function: legal input -> correct output illegal input -> informative output / return value Writing OS and other system programs: "garbage in, garbage out" is a very bad attitude! 4
5 Errors From C Library Functions Most C library functions deal with errors by doing two things: 1. returning a special value (like NULL for fopen) 2. setting the system variable errno errno is zero at start of program errno is not always reset when library functions are successful. to query errno, include <errno.h> User program should never change errno. 5
6 Error-Handling Steps Situation: You call a C library function like fopen, where an error is possible. 1. Check return value to see if error may have occurred (NULL for fopen). 2. If return value indicates possible error, check errno to verify error & find out what kind. 3. Report error to user and recover or end program. 6
7 Your Choices For Reporting Errors 1. ignore possibility of error bad idea except for quick throwaway programs! OR: check return value, and if it tells you there was an error: 2. write a general error message "could not open file", etc. OR: 3. compare errno with applicable error codes & write your own error message OR: 4. use library function to write an error message based on errno 7
8 Library Functions for Dealing With errno char *strerror(int errnum) Returns a string describing the error. Call this with errno as parameter and use the result in an error message. void perror(char *msg) Prints an error message to standard error, based on errno. If msg is not null, prints it first Libraries to include: <errno.h>: defines errno and macros for specific error values <string.h>: strerror & perror functions demo: IOtest1.c 8
9 My Advice Check results from library functions. If result indicates an error: report with perror. If simple way to recover, do it. Otherwise, abort program. What's important: realize that errors can occur error might be because of bug in program or bad input user needs to be told about nature of error aborting with informative error message is sometimes OK re-prompting in interactive program is OK crashing or behaving incorrectly because of error is not acceptable in a production program 9
10 Predefined File Pointers stdin, stdout, stderr: all declared in <stdio.h> stdin takes input from keyboard unless program is being run with standard input redirected stdout & stderr: writes to the screen unless program is being run with standard output/error redirected 10
11 Character-By-Character Input To read one character from a file: int getc(file *fp) Reads a single character from the file, not skipping white space. In case of error or end of file, returns EOF. How to tell the difference? errno To read one character from standard input: getchar() is equivalent to getc(stdin) demo: (IOtest2.c) 11
12 "ungetting" Characters int ungetc (int c, FILE *stream) "pushes" a character back onto the input stream Normally, c is the last character read from the file, but that's not required Most implementations only support one character pushback. Doesn't change the file, just "remembers" the pushed-back char. Why is this useful? Often you have to read one character after the end of something to realise you reached the end. Demo: IOtest3.c 12
13 Writing Characters int putc(int c, FILE *stream) Return value is: EOF if there was an error c if character was written To write one character to standard output: putchar(c) is equivalent to putc(c, stdout) 13
14 Writing Lines int fputs (char *s, FILE *stream) Writes s to the file. Does not write null or end of line at the end. If error: return value is EOF. int puts (char *s) Writes s to the standard output file with '\n' at the end. If error: return value is EOF. 14
15 Reading Lines char* fgets (char *s, int count, FILE *stream) Reads characters from the file into s until it reaches the end of the line or has read count-1 characters. Does not skip white space in the input. Always includes a null character at the end. If error or already at end of file: returns NULL (how can you tell the difference?) Otherwise, returns s. Demo: IOtest5.c 15
16 Reading Lines From Standard Input char* gets (char *s) Reads a line from the standard input. Dangerous don't use! (Why?) 16
17 Formatted Output We've already discussed printf: formatted output to standard output Formatted output to a file: int fprintf (FILE *stream, char *template,...) Return value: number of items printed -- or negative value if error 17
18 Formatted Input We've already discussed scanf: formatted input from standard input. Return value: number of values read EOF if hit end of file before any values read EOF if I/O error Input from a file: int fscanf (FILE *stream, const char *template,...) 18
19 "Output" To a String int sprintf (char *s, char *template,...) Formats output according to a template and copies to s instead of writing to a file. Always writes a null character at the end. Difficult to guarantee safety! Use with extreme care. Safe use of sprintf: IOtest6.c There are alternative versions of sprintf: one takes a maximum length as a parameter one allocates space for a result string on the heap 19
20 Closing Files When you're all done with a file: fclose(file); Two reasons to call fclose: 1. For an output file, makes sure all buffered output gets to the file. 2. Releases resources used by the file (on the heap). Result of fclose is an int: 0 if file was closed successfully EOF if an error occured 20
File Access. FILE * fopen(const char *name, const char * mode);
File Access, K&R 7.5 Dealing with named files is surprisingly similar to dealing with stdin and stdout. Start by declaring a "file pointer": FILE *fp; /* See Appendix B1.1, pg. 242 */ header
More informationStandard File Pointers
1 Programming in C Standard File Pointers Assigned to console unless redirected Standard input = stdin Used by scan function Can be redirected: cmd < input-file Standard output = stdout Used by printf
More informationInput / Output Functions
CSE 2421: Systems I Low-Level Programming and Computer Organization Input / Output Functions Presentation G Read/Study: Reek Chapter 15 Gojko Babić 10-03-2018 Input and Output Functions The stdio.h contain
More informationAccessing Files in C. Professor Hugh C. Lauer CS-2303, System Programming Concepts
Accessing Files in C Professor Hugh C. Lauer CS-2303, System Programming Concepts (Slides include materials from The C Programming Language, 2 nd edition, by Kernighan and Ritchie, Absolute C++, by Walter
More informationFile IO and command line input CSE 2451
File IO and command line input CSE 2451 File functions Open/Close files fopen() open a stream for a file fclose() closes a stream One character at a time: fgetc() similar to getchar() fputc() similar to
More informationQuick review of previous lecture Ch6 Structure Ch7 I/O. EECS2031 Software Tools. C - Structures, Unions, Enums & Typedef (K&R Ch.
1 Quick review of previous lecture Ch6 Structure Ch7 I/O EECS2031 Software Tools C - Structures, Unions, Enums & Typedef (K&R Ch.6) Structures Basics: Declaration and assignment Structures and functions
More informationContent. Input Output Devices File access Function of File I/O Redirection Command-line arguments
File I/O Content Input Output Devices File access Function of File I/O Redirection Command-line arguments UNIX and C language C is a general-purpose, high-level language that was originally developed by
More informationCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 18 I/O in C Standard C Library I/O commands are not included as part of the C language. Instead, they are part of the Standard C Library. A collection of functions and macros that must be implemented
More informationCSci 4061 Introduction to Operating Systems. Input/Output: High-level
CSci 4061 Introduction to Operating Systems Input/Output: High-level I/O Topics First, cover high-level I/O Next, talk about low-level device I/O I/O not part of the C language! High-level I/O Hide device
More informationCS113: Lecture 7. Topics: The C Preprocessor. I/O, Streams, Files
CS113: Lecture 7 Topics: The C Preprocessor I/O, Streams, Files 1 Remember the name: Pre-processor Most commonly used features: #include, #define. Think of the preprocessor as processing the file so as
More informationComputer Programming: Skills & Concepts (CP1) Files in C. 18th November, 2010
Computer Programming: Skills & Concepts (CP1) Files in C 18th November, 2010 CP1 26 slide 1 18th November, 2010 Today s lecture Character oriented I/O (revision) Files and streams Opening and closing files
More informationComputer Security. Robust and secure programming in C. Marius Minea. 12 October 2017
Computer Security Robust and secure programming in C Marius Minea marius@cs.upt.ro 12 October 2017 In this lecture Write correct code minimizing risks with proper error handling avoiding security pitfalls
More informationC Input/Output. Before we discuss I/O in C, let's review how C++ I/O works. int i; double x;
C Input/Output Before we discuss I/O in C, let's review how C++ I/O works. int i; double x; cin >> i; cin >> x; cout
More informationCS246 Spring14 Programming Paradigm Files, Pipes and Redirection
1 Files 1.1 File functions Opening Files : The function fopen opens a file and returns a FILE pointer. FILE *fopen( const char * filename, const char * mode ); The allowed modes for fopen are as follows
More information25.2 Opening and Closing a File
Lecture 32 p.1 Faculty of Computer Science, Dalhousie University CSCI 2132 Software Development Lecture 32: Dynamically Allocated Arrays 26-Nov-2018 Location: Chemistry 125 Time: 12:35 13:25 Instructor:
More informationMode Meaning r Opens the file for reading. If the file doesn't exist, fopen() returns NULL.
Files Files enable permanent storage of information C performs all input and output, including disk files, by means of streams Stream oriented data files are divided into two categories Formatted data
More informationStandard C Library Functions
Demo lecture slides Although I will not usually give slides for demo lectures, the first two demo lectures involve practice with things which you should really know from G51PRG Since I covered much of
More informationComputer Programming: Skills & Concepts (CP) Files in C
CP 20 slide 1 Tuesday 21 November 2017 Computer Programming: Skills & Concepts (CP) Files in C Julian Bradfield Tuesday 21 November 2017 Today s lecture Character oriented I/O (revision) Files and streams
More informationSystem Software Experiment 1 Lecture 7
System Software Experiment 1 Lecture 7 spring 2018 Jinkyu Jeong ( jinkyu@skku.edu) Computer Systems Laboratory Sungyunkwan University http://csl.skku.edu SSE3032: System Software Experiment 1, Spring 2018
More informationFiles. Programs and data are stored on disk in structures called files Examples. a.out binary file lab1.c - text file term-paper.
File IO part 2 Files Programs and data are stored on disk in structures called files Examples a.out binary file lab1.c - text file term-paper.doc - binary file Overview File Pointer (FILE *) Standard:
More informationProgramming in C. Session 8. Seema Sirpal Delhi University Computer Centre
Programming in C Session 8 Seema Sirpal Delhi University Computer Centre File I/O & Command Line Arguments An important part of any program is the ability to communicate with the world external to it.
More informationFile (1A) Young Won Lim 11/25/16
File (1A) Copyright (c) 2010-2016 Young W. Lim. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version
More informationComputer Programming Unit v
READING AND WRITING CHARACTERS We can read and write a character on screen using printf() and scanf() function but this is not applicable in all situations. In C programming language some function are
More informationDay14 A. Young W. Lim Tue. Young W. Lim Day14 A Tue 1 / 15
Day14 A Young W. Lim 2017-12-26 Tue Young W. Lim Day14 A 2017-12-26 Tue 1 / 15 Outline 1 Based on 2 C Strings (1) Characters and Strings Unformatted IO Young W. Lim Day14 A 2017-12-26 Tue 2 / 15 Based
More information2009 S2 COMP File Operations
2009 S2 COMP1921 9. File Operations Oliver Diessel odiessel@cse.unsw.edu.au Last updated: 16:00 22 Sep 2009 9. File Operations Topics to be covered: Streams Text file operations Binary file operations
More informationCSC209H Lecture 3. Dan Zingaro. January 21, 2015
CSC209H Lecture 3 Dan Zingaro January 21, 2015 Streams (King 22.1) Stream: source of input or destination for output We access a stream through a file pointer (FILE *) Three streams are available without
More informationDay14 A. Young W. Lim Thr. Young W. Lim Day14 A Thr 1 / 14
Day14 A Young W. Lim 2017-11-02 Thr Young W. Lim Day14 A 2017-11-02 Thr 1 / 14 Outline 1 Based on 2 C Strings (1) Characters and Strings Unformatted IO Young W. Lim Day14 A 2017-11-02 Thr 2 / 14 Based
More informationFile I/O. Arash Rafiey. November 7, 2017
November 7, 2017 Files File is a place on disk where a group of related data is stored. Files File is a place on disk where a group of related data is stored. C provides various functions to handle files
More informationSWEN-250 Personal SE. Introduction to C
SWEN-250 Personal SE Introduction to C A Bit of History Developed in the early to mid 70s Dennis Ritchie as a systems programming language. Adopted by Ken Thompson to write Unix on a the PDP-11. At the
More informationCS240: Programming in C
CS240: Programming in C Lecture 13 si 14: Unix interface for working with files. Cristina Nita-Rotaru Lecture 13/Fall 2013 1 Working with Files (I/O) File system: specifies how the information is organized
More informationInput/Output and the Operating Systems
Input/Output and the Operating Systems Fall 2015 Jinkyu Jeong (jinkyu@skku.edu) 1 I/O Functions Formatted I/O printf( ) and scanf( ) fprintf( ) and fscanf( ) sprintf( ) and sscanf( ) int printf(const char*
More informationFile I/O. Preprocessor Macros
Computer Programming File I/O. Preprocessor Macros Marius Minea marius@cs.upt.ro 4 December 2017 Files and streams A file is a data resource on persistent storage (e.g. disk). File contents are typically
More informationIO = Input & Output 2
Input & Output 1 IO = Input & Output 2 Idioms 3 Input and output in C are simple, in theory, because everything is handled by function calls, and you just have to look up the documentation of each function
More informationProgramming & Data Structure
File Handling Programming & Data Structure CS 11002 Partha Bhowmick http://cse.iitkgp.ac.in/ pb CSE Department IIT Kharagpur Spring 2012-2013 File File Handling File R&W argc & argv (1) A file is a named
More informationFile Handling. 21 July 2009 Programming and Data Structure 1
File Handling 21 July 2009 Programming and Data Structure 1 File handling in C In C we use FILE * to represent a pointer to a file. fopen is used to open a file. It returns the special value NULL to indicate
More informationContinued from previous lecture
The Design of C: A Rational Reconstruction: Part 2 Jennifer Rexford Continued from previous lecture 2 Agenda Data Types Statements What kinds of operators should C have? Should handle typical operations
More informationSystems Programming. 08. Standard I/O Library. Alexander Holupirek
Systems Programming 08. Standard I/O Library Alexander Holupirek Database and Information Systems Group Department of Computer & Information Science University of Konstanz Summer Term 2008 Last lecture:
More informationPointers and File Handling
1 Pointers and File Handling From variables to their addresses Pallab Dasgupta Professor, Dept. of Computer Sc & Engg INDIAN INSTITUTE OF TECHNOLOGY KHARAGPUR 2 Basics of Pointers INDIAN INSTITUTE OF TECHNOLOGY
More informationCSE2301. Introduction. Streams and Files. File Access Random Numbers Testing and Debugging. In this part, we introduce
Warning: These notes are not complete, it is a Skelton that will be modified/add-to in the class. If you want to us them for studying, either attend the class or get the completed notes from someone who
More informationEM108 Software Development for Engineers
EE108 Section 4 Files page 1 of 14 EM108 Software Development for Engineers Section 4 - Files 1) Introduction 2) Operations with Files 3) Opening Files 4) Input/Output Operations 5) Other Operations 6)
More informationUNIX System Programming
File I/O 경희대학교컴퓨터공학과 조진성 UNIX System Programming File in UNIX n Unified interface for all I/Os in UNIX ü Regular(normal) files in file system ü Special files for devices terminal, keyboard, mouse, tape,
More informationC for Engineers and Scientists: An Interpretive Approach. Chapter 14: File Processing
Chapter 14: File Processing Files and Streams C views each file simply as a sequential stream of bytes. It ends as if there is an end-of-file marker. The data structure FILE, defined in stdio.h, stores
More informationIntroduction to Programming in C Department of Computer Science and Engineering. Lecture No. #47. File Handling
Introduction to Programming in C Department of Computer Science and Engineering Lecture No. #47 File Handling In this video, we will look at a few basic things about file handling in C. This is a vast
More informationCSE 410: Systems Programming
CSE 410: Systems Programming Input and Output Ethan Blanton Department of Computer Science and Engineering University at Buffalo I/O Kernel Services We have seen some text I/O using the C Standard Library.
More informationCS240: Programming in C. Lecture 14: Errors
CS240: Programming in C Lecture 14: Errors Errors We ve already seen a number of instances where unexpected (and uncaught) errors can take place: Memory buffer overflow/underflow unintended casts misuse
More informationBasic I/O. COSC Software Tools. Streams. Standard I/O. Standard I/O. Formatted Output
Basic I/O COSC2031 - Software Tools C - Input/Output (K+R Ch. 7) We know how to do some basic input and output: getchar - reading characters putchar - writing characters printf - formatted output Input
More informationThe Design of C: A Rational Reconstruction: Part 2
The Design of C: A Rational Reconstruction: Part 2 1 Continued from previous lecture 2 Agenda Data Types Operators Statements I/O Facilities 3 Operators Issue: What kinds of operators should C have? Thought
More informationPROGRAMMAZIONE I A.A. 2017/2018
PROGRAMMAZIONE I A.A. 2017/2018 INPUT/OUTPUT INPUT AND OUTPUT Programs must be able to write data to files or to physical output devices such as displays or printers, and to read in data from files or
More information8. Characters, Strings and Files
REGZ9280: Global Education Short Course - Engineering 8. Characters, Strings and Files Reading: Moffat, Chapter 7, 11 REGZ9280 14s2 8. Characters and Arrays 1 ASCII The ASCII table gives a correspondence
More informationNaked C Lecture 6. File Operations and System Calls
Naked C Lecture 6 File Operations and System Calls 20 August 2012 Libc and Linking Libc is the standard C library Provides most of the basic functionality that we've been using String functions, fork,
More informationC Basics And Concepts Input And Output
C Basics And Concepts Input And Output Report Working group scientific computing Department of informatics Faculty of mathematics, informatics and natural sciences University of Hamburg Written by: Marcus
More informationC programming basics T3-1 -
C programming basics T3-1 - Outline 1. Introduction 2. Basic concepts 3. Functions 4. Data types 5. Control structures 6. Arrays and pointers 7. File management T3-2 - 3.1: Introduction T3-3 - Review of
More informationUNIT IV-2. The I/O library functions can be classified into two broad categories:
UNIT IV-2 6.0 INTRODUCTION Reading, processing and writing of data are the three essential functions of a computer program. Most programs take some data as input and display the processed data, often known
More informationAdvanced C Programming Topics
Introductory Medical Device Prototyping Advanced C Programming Topics, http://saliterman.umn.edu/ Department of Biomedical Engineering, University of Minnesota Operations on Bits 1. Recall there are 8
More informationDATA STRUCTURES USING C
DATA STRUCTURES USING C File Handling in C Goals By the end of this unit you should understand how to open a file to write to it. how to open a file to read from it. how to open a file to append data to
More informationPrinceton University Computer Science 217: Introduction to Programming Systems The Design of C
Princeton University Computer Science 217: Introduction to Programming Systems The Design of C C is quirky, flawed, and an enormous success. While accidents of history surely helped, it evidently satisfied
More informationProgramming. Functions and File I/O
Programming Functions and File I/O Summary Functions Definition Declaration Invocation Pass by value vs. pass by reference File I/O Reading Writing Static keyword Global vs. local variables 2 Functions
More informationUNIT-V CONSOLE I/O. This section examines in detail the console I/O functions.
UNIT-V Unit-5 File Streams Formatted I/O Preprocessor Directives Printf Scanf A file represents a sequence of bytes on the disk where a group of related data is stored. File is created for permanent storage
More informationBinghamton University. CS-211 Fall Input and Output. Streams and Stream IO
Input and Output Streams and Stream IO 1 Standard Input and Output Need: #include Large list of input and output functions to: Read and write from a stream Open a file and make a stream Close
More informationShould you know scanf and printf?
C-LANGUAGE INPUT & OUTPUT C-Language Output with printf Input with scanf and gets_s and Defensive Programming Copyright 2016 Dan McElroy Should you know scanf and printf? scanf is only useful in the C-language,
More informationContents. A Review of C language. Visual C Visual C++ 6.0
A Review of C language C++ Object Oriented Programming Pei-yih Ting NTOU CS Modified from www.cse.cuhk.edu.hk/~csc2520/tuto/csc2520_tuto01.ppt 1 2 3 4 5 6 7 8 9 10 Double click 11 12 Compile a single source
More informationStandard I/O in C, Computer System and programming in C
Standard I/O in C, Contents 1. Preface/Introduction 2. Standardization and Implementation 3. File I/O 4. Standard I/O Library 5. Files and Directories 6. System Data Files and Information 7. Environment
More informationCS102: Standard I/O. %<flag(s)><width><precision><size>conversion-code
CS102: Standard I/O Our next topic is standard input and standard output in C. The adjective "standard" when applied to "input" or "output" could be interpreted to mean "default". Typically, standard output
More informationSystem Programming. Standard Input/Output Library (Cont d)
Content : by Dr. B. Boufama School of Computer Science University of Windsor Instructor: Dr. A. Habed adlane@cs.uwindsor.ca http://cs.uwindsor.ca/ adlane/60-256 Content Content 1 Binary I/O 2 3 4 5 Binary
More informationCS201 Lecture 2 GDB, The C Library
CS201 Lecture 2 GDB, The C Library RAOUL RIVAS PORTLAND STATE UNIVERSITY Announcements 2 Multidimensional Dynamically Allocated Arrays Direct access support. Same as Multidimensional Static Arrays No direct
More informationLecture 12 CSE July Today we ll cover the things that you still don t know that you need to know in order to do the assignment.
Lecture 12 CSE 110 20 July 1992 Today we ll cover the things that you still don t know that you need to know in order to do the assignment. 1 The NULL Pointer For each pointer type, there is one special
More informationCourse organization. Course introduction ( Week 1)
Course organization Course introduction ( Week 1) Code editor: Emacs Part I: Introduction to C programming language (Week 2-9) Chapter 1: Overall Introduction (Week 1-3) Chapter 2: Types, operators and
More informationCS 220: Introduction to Parallel Computing. Input/Output II. Lecture 8
CS 220: Introduction to Parallel Computing Input/Output II Lecture 8 Today s Agenda Debugging and I/O Buffering I/O Streams Writing files 2/7/18 CS 220: Parallel Computing 2 Today s Agenda Debugging and
More informationStream Model of I/O. Basic I/O in C
Stream Model of I/O 1 A stream provides a connection between the process that initializes it and an object, such as a file, which may be viewed as a sequence of data. In the simplest view, a stream object
More informationUNIX input and output
UNIX input and output Disk files In UNIX a disk file is a finite sequence of bytes, usually stored on some nonvolatile medium. Disk files have names, which are called paths. We won t discuss file naming
More informationText Output and Input; Redirection
Text Output and Input; Redirection see K&R, chapter 7 Simple Output puts(), putc(), printf() 1 Simple Output The simplest form of output is ASCII text. ASCII occurs as single characters, and as nullterminated
More informationWhat Is Operating System? Operating Systems, System Calls, and Buffered I/O. Academic Computers in 1983 and Operating System
What Is Operating System? Operating Systems, System Calls, and Buffered I/O emacs gcc Browser DVD Player Operating System CS 217 1 Abstraction of hardware Virtualization Protection and security 2 Academic
More information7/21/ FILE INPUT / OUTPUT. Dong-Chul Kim BioMeCIS UTA
7/21/2014 1 FILE INPUT / OUTPUT Dong-Chul Kim BioMeCIS CSE @ UTA What s a file? A named section of storage, usually on a disk In C, a file is a continuous sequence of bytes Examples for the demand of a
More informationGoals of this Lecture
I/O Management 1 Goals of this Lecture Help you to learn about: The Unix stream concept Standard C I/O functions Unix system-level functions for I/O How the standard C I/O functions use the Unix system-level
More informationI/O Management! Goals of this Lecture!
I/O Management! 1 Goals of this Lecture! Help you to learn about:" The Unix stream concept" Standard C I/O functions" Unix system-level functions for I/O" How the standard C I/O functions use the Unix
More informationI/O Management! Goals of this Lecture!
I/O Management! 1 Goals of this Lecture! Help you to learn about:" The Unix stream concept" Standard C I/O functions" Unix system-level functions for I/O" How the standard C I/O functions use the Unix
More informationData File and File Handling
Types of Disk Files Data File and File Handling Text streams are associated with text-mode files. Text-mode files consist of a sequence of lines. Each line contains zero or more characters and ends with
More informationSimple Output and Input. see chapter 7
Simple Output and Input see chapter 7 Simple Output puts(), putc(), printf() Simple Output The simplest form of output is ASCII text. ASCII occurs as single characters, and as nullterminated text strings
More informationWriting to and reading from files
Writing to and reading from files printf() and scanf() are actually short-hand versions of more comprehensive functions, fprintf() and fscanf(). The difference is that fprintf() includes a file pointer
More informationHIGH LEVEL FILE PROCESSING
HIGH LEVEL FILE PROCESSING 1. Overview The learning objectives of this lab session are: To understand the functions used for file processing at a higher level. o These functions use special structures
More informationInput/Output: Advanced Concepts
Input/Output: Advanced Concepts CSE 130: Introduction to Programming in C Stony Brook University Related reading: Kelley/Pohl 1.9, 11.1 11.7 Output Formatting Review Recall that printf() employs a control
More informationEECS2031. Modifiers. Data Types. Lecture 2 Data types. signed (unsigned) int long int long long int int may be omitted sizeof()
Warning: These notes are not complete, it is a Skelton that will be modified/add-to in the class. If you want to us them for studying, either attend the class or get the completed notes from someone who
More informationCSI 402 Systems Programming LECTURE 4 FILES AND FILE OPERATIONS
CSI 402 Systems Programming LECTURE 4 FILES AND FILE OPERATIONS A mini Quiz 2 Consider the following struct definition struct name{ int a; float b; }; Then somewhere in main() struct name *ptr,p; ptr=&p;
More informationCSI 402 Lecture 2 Working with Files (Text and Binary)
CSI 402 Lecture 2 Working with Files (Text and Binary) 1 / 30 AQuickReviewofStandardI/O Recall that #include allows use of printf and scanf functions Example: int i; scanf("%d", &i); printf("value
More informationChapter 10: File Input / Output
C: Chapter10 Page 1 of 6 C Tutorial.......... File input/output Chapter 10: File Input / Output OUTPUT TO A FILE Load and display the file named formout.c for your first example of writing data to a file.
More informationstructs as arguments
Structs A collection of related data items struct record { char name[maxname]; int count; ; /* The semicolon is important! It terminates the declaration. */ struct record rec1; /*allocates space for the
More informationfopen() fclose() fgetc() fputc() fread() fwrite()
The ability to read data from and write data to files is the primary means of storing persistent data, data that does not disappear when your program stops running. The abstraction of files that C provides
More informationLecture 7: Files. opening/closing files reading/writing strings reading/writing numbers (conversion to ASCII) command line arguments
Lecture 7: Files opening/closing files reading/writing strings reading/writing numbers (conversion to ASCII) command line arguments Lecture 5: Files, I/O 0IGXYVI*MPIW 0 opening/closing files reading/writing
More informationENG120. Misc. Topics
ENG120 Misc. Topics Topics Files in C Using Command-Line Arguments Typecasting Working with Multiple source files Conditional Operator 2 Files and Streams C views each file as a sequence of bytes File
More informationC Programming 1. File Access. Goutam Biswas. Lect 29
C Programming 1 File Access C Programming 2 Standard I/O So far all our I/O operations are read from the standard input (stdin - keyboard) and write to the standard output (stdout - VDU) devices. These
More informationCMPT 102 Introduction to Scientific Computer Programming. Input and Output. Your first program
CMPT 102 Introduction to Scientific Computer Programming Input and Output Janice Regan, CMPT 102, Sept. 2006 0 Your first program /* My first C program */ /* make the computer print the string Hello world
More informationIntroduction to file management
1 Introduction to file management Some application require input to be taken from a file and output is required to be stored in a file. The C language provides the facility of file input-output operations.
More informationTHE C STANDARD LIBRARY & MAKING YOUR OWN LIBRARY. ISA 563: Fundamentals of Systems Programming
THE C STANDARD LIBRARY & MAKING YOUR OWN LIBRARY ISA 563: Fundamentals of Systems Programming Announcements Homework 2 posted Homework 1 due in two weeks Typo on HW1 (definition of Fib. Sequence incorrect)
More informationHow do we define pointers? Memory allocation. Syntax. Notes. Pointers to variables. Pointers to structures. Pointers to functions. Notes.
, 1 / 33, Summer 2010 Department of Computer Science and Engineering York University Toronto June 15, 2010 Table of contents, 2 / 33 1 2 3 Exam, 4 / 33 You did well Standard input processing Testing Debugging
More informationC for C++ Programmers
C for C++ Programmers CS230/330 - Operating Systems (Winter 2001). The good news is that C syntax is almost identical to that of C++. However, there are many things you're used to that aren't available
More informationCSC 1107: Structured Programming
CSC 1107: Structured Programming J. Kizito Makerere University e-mail: www: materials: e-learning environment: office: alt. office: jkizito@cis.mak.ac.ug http://serval.ug/~jona http://serval.ug/~jona/materials/csc1107
More informationCSC 1107: Structured Programming
CSC 1107: Structured Programming J. Kizito Makerere University e-mail: www: materials: e-learning environment: office: jkizito@cis.mak.ac.ug http://serval.ug/~jona http://serval.ug/~jona/materials/csc1107
More informationWhat did we talk about last time? Selection Loops Lab 3
Week 4 - Monday What did we talk about last time? Selection Loops Lab 3 Unix was not designed to stop its users from doing stupid things, as that would also stop them from doing clever things. Doug Gwyn
More informationOperating System Labs. Yuanbin Wu
Operating System Labs Yuanbin Wu cs@ecnu Operating System Labs Introduction to Unix (*nix) Course Overview Operating System Labs Introduction to Unix (*nix) Course Overview Unix / *nix What An familiy
More informationChapter 5, Standard I/O. Not UNIX... C standard (library) Why? UNIX programmed in C stdio is very UNIX based
Chapter 5, Standard I/O Not UNIX... C standard (library) Why? UNIX programmed in C stdio is very UNIX based #include FILE *f; Standard files (FILE *varname) variable: stdin File Number: STDIN_FILENO
More information