File I/O

Question 1

types of memory storage

Answer 1

RAM -random access memory-volatile
if power is interupted then it’s data or any changes made is lost
contents are lost when program terminates.

harddisk-non-volatile means if power is interrupted data or changes made is not lost

a program is run in RAM and it has to access some file stored in harddisk it is done by File I/O which can be done using C also.

files are used to persist the data

Question 2

Operations on Files

Answer 2

create a file
open a file
close a file
read a file
write a file

Question 3

Types of Files

Answer 3

Text Files
-textual data
-.txt,.c

Binary Files
-binary data
-.exe,.mp3.jpg

Question 4

File pointers

Answer 4

FILE is a structure that needs to be created before opening a file
a FILE ptr points to this structure and is used to access this file

FILE *fptr;

Question 5

Open and Close a file

Answer 5

Opening a file

FILE *fptr;
fptr=fopen(“file name”,mode);

mode=
“r”-read
“rb”-read in binary
“w”-write
“wb”-write in binary
“a”-append

Closing a file

fclose(fptr);

if a file doesn’t exist and we try to read it then the pointer will show null
if a file doesn’t exist and we try to write it that file is created

Question 6

Read from a file

Answer 6

char ch;
fscanf(fptr,”%c”,&ch);
printf(“%c”,ch);

Question 7

write to a file

Answer 7

after switching to write mode

char ch=”a”;
fprintf(fptr,”%c”,ch);

we can also append files

Question 8

Read and write using special functions

Answer 8

fgetc(fptr)-read character
fputc(‘A’,fptr)-put character into file

both of these code serves the same purpose

fscanf(fptr,”%c”,&ch);
printf(“%c\n”,fgetc(fptr));

fprintf(fptr,”%c”,ch);
fputc(‘a’,fptr);

this is only for characters

Question 9

EOF

Answer 9

EOF -End of file
fgetc returns EOF to show that the file has ended

char ch;
ch=fgetc(fptr);
while (ch!=EOF)
{
printf(“%c”,ch);
ch=fgetc(fptr);
}
printf(“\n”);

}