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#include<stdio.h>int main() {FILE *file; char sentence[50]; int i;file = fopen("sentence.txt", "w+"); /* we create a file for reading and writing */if(file==NULL) { printf("Error: can't create file.\n");return 1; }else { printf("File created successfully.\n");printf("Enter a sentence less than 50 characters: "); gets(sentence);for(i=0 ; sentence[i] ; i++) {fputc(sentence[i], file);} rewind(file); /* reset the file pointer's position */ printf("Contents of the file: \n\n");while(!feof(file)) { printf("%c", fgetc(file));} printf("\n");fclose(file); return 0;} }
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Output depends on what you entered. First of all, we stored the inputted sentence in a char array, since we're writing to a file one character at a time it'd be useful to detect for the null character. Recall that the null character, \0, returns 0, so putting sentence[i] in the condition part of the for loop iterates until the null character is met.

Then we call rewind, which takes the file pointer to the beginning of the file, so we can read from it. In the while loop we print the contents a character at a time, until we reach the end of the file - determined by using the feof function.

Note that it is essential to have the include file stdio.h referenced at the top of your program in order to use any of these functions: fscanf(), fgets(), fgetc(), fflush(), fprintf(), fputs(), fputc(), feof(), fseek() và rewind().

Eof and errors

When a function returns EOF (or, occasionally, 0 or NULL, as in the case of fread and fgets respectively), we commonly say that we have reached “end of file” but it turns out that it's also possible that there's been some kind of I/O error. When you want to distinguish between end-of-file and error, you can do so with the feof and ferror functions. feof(fp) returns nonzero (that is, “true”) if end-of-file has been reached on the file pointer fp, and ferror(fp) returns nonzero if there has been an error.

Notice feof returns nonzero if end-of-file has been reached. It does not tell you that the next attempt to read from the stream will reach end-of-file, but rather that the previous attempt (by some other function) already did. (If you know Pascal, you may notice that the end-of-file detection situation in C is therefore quite different from Pascal.) Therefore, you would never write a loop like

while(!feof(fp)) fgets(line, max, fp);

Instead, check the return value of the input function directly:

while(fgets(line, max, fp) != NULL)

With a very few possible exceptions, you don't use feof to detect end-of-file; you use feof or ferror to distinguish between end-of-file and error. (You can also use ferror to diagnose error conditions on output files.)

Since the end-of-file and error conditions tend to persist on a stream, it's sometimes necessary to clear (reset) them, which you can do with clearerr(FILE *fp) .

What should your program do if it detects an I/O error? Certainly, it cannot continue as usual; usually, it will print an error message. The simplest error messages are of the form

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
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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