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  • No special processing of the data occurs and each byte of data is transferred to or from the disk unprocessed.
  • C Programming Language places no constructs on the file, and it may be read from, or written to, in any manner chosen by the programmer.

Binary files can be either processed sequentially or, depending on the needs of the application, they can be processed using random access techniques. In C Programming Language, processing a file using random access techniques involves moving the current file position to an appropriate place in the file before reading or writing data. This indicates a second characteristic of binary files – they a generally processed using read and write operations simultaneously.

For example, a database file will be created and processed as a binary file. A record update operation will involve locating the appropriate record, reading the record into memory, modifying it in some way, and finally writing the record back to disk at its appropriate location in the file. These kinds of operations are common to many binary files, but are rarely found in applications that process text files.

For all file operations you should always follow the 5-step plan as outlined below.

  1. Declare file pointer.
  2. Attach the file pointer to the file (open file).
  3. Check file opened correctly.
  4. Read or Write the data from or to the file.
  5. Close the file.

Operations on files


In C, we usually create variables of type FILE * to point to a file located on the computer.

FILE *file_pointer_name;


FILE * f1, * f2;

Open files

First things first: we have to open a file to be able to do anything else with it. For this, we use fopen function, like all the I/O functions, is made available by the stdio.h library. The fopen() function prototype is as follows.

FILE *fopen(char *filename, char *mode);

In the above prototype, there are two arguments:

  • filename is a string containing the name of the file to be opened. So if your file sits in the same directory as your C source file, you can simply enter the filename in here - this is probably the one you'll use most.
  • mode determines how the file may be accessed.
Mode Meaning
“r” Open a file for read only, starts at beginning of file (default mode).
“w” Write-only, truncates existing file to zero length or create a new file for writing.
“a” Write-only, starts at end of file if file exists,otherwise creates a new file for writing.
“r+” Open a file for read-write, starts at beginning of file. If the file is not exist, it will cause an error.
“w+” Read-write, truncates existing file to zero length or creates a new file for reading and writing.
“a+” Read-write, starts at end of file if file exists, otherwise creates a new file for reading and writing.

So there are 12 different values that could be used: "rt", "wt", "at", "r+t", "w+t", "a+t" and "rb", "wb", "ab", "r+b", "w+b", "a+b".

Character Type
“t” Text File
“b” Binary File
When work with the text file, you also can use only "r", "w", "a", "r", "w”, "a", instead of "rt", "wt", "at", "r+t", "w+t", "a+t" respectively.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Introduction to computer science. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10776/1.1
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