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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

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
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how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
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I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
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I rally confuse this number And equations too I need exactly help
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Commplementary angles
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what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
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Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
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I'm interested in nanotube
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Ramkumar Reply
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what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele 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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