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Write the program opens the file called myfile.txt, and counts the number of characters that it contains by reading all of them one by one. Finally the total amount of bytes is printed out.

#include<stdio.h>int main () {FILE * fp; long n = 0;fp = fopen ("myfile.txt","rb"); if (fp==NULL) printf ("Error opening file");else {while (!feof(fp)) { fgetc (fp);n++; }fclose (fp); printf ("Total number of bytes: %d\n",n);} return 0;}
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Opens a file called input.txt which has some random text (less than 200 characters), stores each character in an array, then spits them back out into another file called "output.txt" in reverse order:

#include<stdio.h>int main() { char c; /* declare a char variable */char name[200]; /* Initialize array of total200 for characters */ FILE *f_input, *f_output; /* declare FILE pointers */int counter = 0; /* Initialize variable for counter to zero */ f_input = fopen("input.txt", "r");/* open a text file for reading */ if(f_input==NULL) {printf("Error: can't open file.\n"); return 1;} else {while(1) { /* loop continuously */ c = fgetc(f_input); /* fetch the next character */if(c==EOF) { /* if end of file reached, break out of loop */break; }else if (counter<200) { /* else put character into array */ name[counter]= c; counter++; /* increment the counter */} else {break; }} fclose(f_input); /* close input file */f_output = fopen("output.txt", "w"); /* create a text file for writing */if(f_output==NULL) { printf("Error: can't create file.\n");return 1; }else { counter--; /* we went one too step far */while(counter>= 0) { /* loop while counter's above zero */ fputc(name[counter], f_output); /* write character into output file */counter--; /* decrease counter */ }fclose(f_output); /* close output file */ printf("All done!\n");return 0; }} }
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Reading one character at a time can be a little inefficient, so we can use fgets to read one line at a time. The fgets() function prototype is as follows.

char *fgets(char *str, int num, FILE *fp);

The fgets() function reads characters from the file associated with fp into a string pointed to by str until num-1 characters have been read, a newline character is encountered, or the end of the file is reached. The string is null-terminated and the newline character is retained.

Return value: the function returns str if successful and a null pointer if an error occurs.

You can't use an !=EOF check here, as we're not reading one character at a time (but you can use feof).

Create a file called myfile.txt in Notepad, include 3 lines and put tabs in the last line.

111 222 333 444 555 666777 888 999 #include<stdio.h>int main() {char c[10]; /* declare a char array */FILE *file; /* declare a FILE pointer */ file = fopen("myfile.txt", "r");/* open a text file for reading */ if(file==NULL){ printf("Error: can't open file.\n");/* fclose(file); DON'T PASS A NULL POINTER TO fclose !! */return 1; }else {printf("File opened successfully. Contents:\n\n");while(fgets(c, 10, file)!=NULL) { /* keep looping until NULL pointer... */printf("String: %s", c); /* print the file one line at a time */} printf("\n\nNow closing file...\n");fclose(file); return 0;} }
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Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
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
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
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
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
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
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit 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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