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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

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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