File
operation in any programming language is meant for saving the data, so it can
be called as data file. C is still is a low-level language if we goes by the
present standard. In C file operations mainly depends on streams of bytes, that
are known as "input streams" or "output streams". C
language does not support any Random files as some of previous languages like
COBOL and BASIC. All required function for File Operations are mentioned in
"stdio.h", it was written by Mike Lesk at Bell Labs in the early
1970s.
FILE
pointer from "stdio.h" must be use to perform File operations.
Example
:
FILE
*fp;
There
are many input/output statement that mainly meant for file operations. If we
opened a file then we should close.
fopen(),
function used to open a file. We can open a file for reading or writing or for
modifying purpose too.
"r"-
Read-Only mode.
"w"-Write-only
mode.
"a"-append
mode.
"r+"-read+write
mode.
"w+"-write+read
mode.
"a+"-read+append
mode.
fclose()
- is for closing a file.
For
reading, writing or searching a record we can using following functions
fgetc()
fgets()
fscanf()
fputc()
fprintf()
fputs()
fseek()
rewind()
Here is
a few example on File Operation, where we will try to cover a few functions
that exclusively related to the file operation.
//Writing and
Reading character wise using putc() and getc()
#include <stdio.h>
#include <conio.h>
#include <string.h>
void
FileWrite()
{
char
Filename[11],sentence[100];
int
i=0;
FILE
*fptr;
fflush(stdin);
printf("\n\tEnter
Filename : ");
gets(Filename);
fflush(stdin);
printf("\n\tEnter
a Sentence : ");
gets(sentence);
fptr=fopen(Filename,"w");
do
{
putc(sentence[i++],
fptr);
}while(sentence[i]!='\0');
fclose(fptr);
}
void
FileRead()
{
char
Filename[11],sentence[100];
int
i=0;
FILE *fptr;
fflush(stdin);
printf("\n\tEnter Filename
: ");
gets(Filename);
if
((fptr = fopen(Filename, "r"))== NULL)
{
printf("\n\n\tFile
Doesnot Exists ");
getch();
return;
}
fptr=fopen(Filename,"r");
while((sentence[i++]=getc(fptr))!=EOF);
sentence[i]='\0';
fclose(fptr);
printf("\n\tSentence
Extract from File is = %s ",sentence);
}
void
main()
{
int
c=0;
clrscr();
while(c<3)
{
printf("\n\n\n\t1.
Write\n\t2.
Read\n\t3. Exit");
printf("\n\tenter
your choice:");
scanf("%d",&c);
switch(c)
{
case
1:FileWrite();break;
case
2:FileRead();break;
}
}
getch();
}
//Writing and
Reading whole string using fputs() and fgets()
#include <stdio.h>
#include <conio.h>
#include <string.h>
FILE
*fp;
int
c;
void
FileCreate()
{
char
wrd[50],ch='y';
int
L;
fp=fopen("Word.txt","w");
while(ch=='y'
|| ch=='Y')
{
fflush(stdin);
printf("\n\tEnter
a String : ");
gets(wrd);
fputs(wrd,fp);
fputs("\n",fp);
fflush(stdin);
printf("\n\tWant
to continue y/n? ");
ch=getche();
}
fclose(fp);
}
void
FileRead()
{
char
wrd[50];
if((fp=fopen("word.txt","r"))==NULL)
{
printf("\n\n\tInvalid Filename");
getch();
return;
}
printf("\n\tStrings
read from the file :");
while(fgets(wrd,50,fp)!=NULL)
{
printf("\n\t%s",wrd);
}
fclose(fp);
}
void
main()
{
int
c=0;
clrscr();
while(c<3)
{
printf("\n\n\n\t1.
Write\n\t2.
Read\n\t3. Exit");
printf("\n\tenter
your choice:");
scanf("%d",&c);
switch(c)
{
case
1:FileCreate();break;
case
2:FileRead();break;
}
}
getch();
}
//Writing and Reading
#include
<stdio.h>
#include <conio.h>
#include <string.h>
void
FileCreate()
{
char
ch='y',name[20];
int
age,i;
FILE
*fp;
fp=fopen("Details.txt","w");
while(ch=='y'
|| ch=='Y')
{
printf("\n\tEnter
name : ");
scanf("%s",&name);
printf("\n\tEnter
age : ");
scanf("%d",&age);
fprintf(fp,"%s
%d",name,age);
printf("\n\tWant
to continue (y/n)? ");
ch=getche();
printf("\n");
}
fclose(fp);
}
void
FileRead()
{
char
name[20];
int
age,i;
FILE
*fp;
fp=fopen("Details.txt","r");
while((fscanf(fp,"%s
%d",&name,&age))!=EOF)
{
printf("\n\n\tname
: %s ",name);
printf("\n\tAge : %d",age);
}
fclose(fp);
getch();
}
void
main()
{
int
c=0;
clrscr();
while(c<3)
{
printf("\n\n\n\t1.
Write\n\t2.
Read\n\t3. Exit");
printf("\n\tenter your
choice:");
scanf("%d",&c);
switch(c)
{
case
1:FileCreate();break;
case
2:FileRead();break;
}
}
getch();
}
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