FILE HANDLING CONCEPT
WRITE MODE:
e
·
Create a pointer variable for the type
structure FILE
·
Use fopen() function to open the file in
write mode ‘w’
·
If the function
returns NULL, print an error message
·
Else use gets
function to get a stream of characters from the user
·
Use fputs()
function which outputs a string to the file pointer variable
·
Close the file
pointer variable using fclose( ) function
·
After running the
program open the file in the corresponding bin folder to view the contents
entered by the user during run time.
PROGRAM
#include
<stdio.h>
#include
<string.h>
void
main()
{
FILE
*fileptr;
//pointer
variable for the type FILE structure
char
ch[100];
clrscr();
fileptr=fopen("WriteDemo.txt","w");
//fopen
function opens a stream for the file mentioned
if(fileptr==NULL)
{
puts("Cant
open file"); //puts outputs a
string and appends a new line character
exit(1);
}
printf("\nEnter
few lines:");
while(strlen(gets(ch))>0)
{
fputs(ch,fileptr);//outputs
a string to a stream
fputs("\n",fileptr);
}
fclose(fileptr);
getch();
}
OUTPUT
Enter few lines: This is a demo to open a file
in write mode
--------------------------------------------------------------------------------------------------------------------------
APPEND MODE:
ALGORITHM:
·
Create a pointer variable for the type
structure FILE
·
Use fopen() function to open the file in
write mode ‘a’
·
If the function
returns NULL, print an error message
·
Else use gets
function to get a stream of characters from the user
·
Use fputs()
function which outputs a string to the file pointer variable
·
Close the file
pointer variable using fclose( ) function
·
After entering, go to the folder C:\TC\BIN
to locate WriteDemo.txt file, that contains the same data entered during run
time along with the existing data. The content of the text file would be This
is a demo to open a file in write mode This is a demo to open a file in append
mode
PROGRAM
#include
<stdio.h>
#include
<string.h>
void
main()
{
FILE
*fileptr;
char
ch[100];
clrscr();
fileptr=fopen("WriteDemo.txt","a");
//fopen
function opens a stream for the file mentioned
if(fileptr==NULL)
{
puts("Cant
open file");
//puts
outputs a string and appends a new line character
exit(1);
}
printf("\nEnter
few lines:");
while(strlen(gets(ch))>0)
{
fputs(ch,fileptr);//outputs
a string to a stream
fputs("\n",fileptr);
}
fclose(fileptr);
getch();
}
OUTPUT
Enter
few lines: This is a demo to open a file in append mode
----------------------------------------------------------------------------------------------------------------
READING CONCEPT:
ALGORITHM:
·
Create a pointer variable for the type
structure FILE
·
Use fopen() function to open the file in
write mode ‘r’
·
If the function
returns NULL, print an error message
·
Loop a fgetc
function to get a character from the stream
·
Print the character
until it reaches End Of File
·
Close the file
pointer variable using fclose( ) function
PROGRAM
#include
<stdio.h>
#include
<conio.h>
void main()
{
FILE
*fileptr;
char ch;
clrscr();
fileptr=fopen("WriteDemo.txt","r");
if(fileptr==NULL)
{
puts("Cant
find file");
exit(1);
}
while(1)
{
ch=fgetc(fileptr);//gets
a character from the stream
printf("%c",ch);
if(ch==EOF)
break;
}
fclose(fileptr);
getch();
}
OUTPUT:
This is a demo
to open a file in write mode
This is a demo to open a file in append
mode
-------------------------------------------------------------------------------------------------------------------------
REMOVING CONTENT:
ALGORITHM:
·
Create two pointer variables for the
type structure FILE
·
Get the name of the existing file to be
renamed from the user and the new name too using gets()
·
Pass them as input arguments to rename
() function and if its successful the file is renamed with new name.
·
Else the function
fails, print an error message
·
Using the first
file pointer variable try to open the file with the old name in read mode with fopen()
·
The function returns NULL as the old
file name doesn’t exists, so an error message is generated
·
Close the file
pointer variable using fclose( ) function
·
Pass the new file name as input argument
to the remove() function which removes the file from the directory
·
Using the second
file pointer variable try to open the file with the new name in read mode with fopen()
·
The function returns NULL as the renamed
file doesn’t exists, so an error message is generated
·
Close the file
pointer variable using fclose( ) function
PROGRAM
#include<stdio.h>
#include<conio.h>
void main()
{
char
oldname[30],newname[30];
FILE
*fptr,*fptr1;
clrscr();
printf("Enter
the file name to be renamed:");
gets(oldname);
printf("\nEnter
the new name:");
gets(newname);
if(rename(oldname,newname)==0)
printf("\nFile
%s renamed to %s",oldname,newname);
else
perror("\nError");
fptr=fopen(oldname,"r");
if(fptr==NULL)
{
printf("\nFile
%s not found",oldname);
}
fclose(fptr);
remove(newname);
fptr1=fopen(newname,"r");
if(fptr1==NULL)
printf("\nFile
%s not found",newname);
fclose(fptr1);
getch();
}
OUTPUT
Enter
the file name to be renamed: oldname.txt
Enter
the new name: newname.txt
File
oldname.txt renamed to newname.txt
File
oldname.txt not found
File newname.txt not found
-------------------------------------------------------------------------------------------------------------------------
COPYING CONTENTS:
ALGORITHM:
·
Create two pointer variables for the
type structure FILE
·
Open the source file in read mode and
target file in write mode using fopen function
·
Assign them to respective pointer
variables
·
Read the source file data character by
character using fgetc() function in a loop until End Of File is reached
·
Once the character is read use fputc
function by passing the character and target file pointer variable as input
arguments as the data is written in the target file by character
·
Close the file
pointer variables using fclose( ) function
·
Check both the
files located in the bin folder to see the same contents
PROGRAM
#include<stdio.h>
#include<conio.h>
void main()
{
FILE *fileptr1, *fileptr2;
char ch;
clrscr();
fileptr1=fopen("Message.txt","r");
//open the source file in read mode
fileptr2=fopen("MessageC.txt","w");
//open the destination file in write mode
//read the source file data character by
character
if(fileptr1==NULL)
{
puts("File not found");
exit(1);
}
while(1)
{
ch=fgetc(fileptr1);
//read a character from a stream in the
fileptr1
if(ch==EOF)
break;
else
putc(ch,fileptr2);
//putc outputs a character to a stream in
fileptr2
}
printf("File copied
successfully..");
fclose(fileptr1);
fclose(fileptr2);
getch();
}
OUTPUT
File copied successfully..
-------------------------------------------------------------------------------------------------------------------------
ACCESSING DATA IN RANDOM MODE:
ALGORITHM:
·
Create a pointer variable for the type
structure FILE
·
Open the file in write mode using fopen
function
·
Write the data to the file using
fwrite() function by passing pointer to any object, length of the data, number
of data to be added and the file pointer variable as input arguments
·
Read the file data character by
character using fseek() function by passing the file pointer variable, a
numeric value which starts to read the data from that position and SEEK_SET
which is 0 begins to read the data by assigning that position as index 0
·
Use fread() function which fread reads a
specified number of equal-sized data items from an input stream into a block.
·
Close the file
pointer variables using fclose( ) function
·
Check both the file
located in the bin folder to see the contents
·
In the output we
will see a part of the message which starts from the numeric value passed in
fseek()
PROGRAM
//File
manipulation using fread, fwrite, fseek
#include
<stdio.h>
#include
<conio.h>
void main()
{
FILE *fptr;
char msg[] = "this is a test";
char buf[20];
clrscr();
if((fptr=fopen("DUMMY.TXT","w+"))==NULL)
{
puts("Cannot open output
file.\n");
}
fwrite(msg,strlen(msg)+1,1,fptr);
fseek(fptr,7,SEEK_SET);
fread(buf,strlen(msg)+1,1,fptr);
printf("%s\n",buf);
fclose(fptr);
getch();
}
OUTPUT
0 comments:
Post a Comment