Question

Explain need of file data and various modes of files also write program to create edit copy of file. 

Answer 1

File Handling :-
             File handling is an important part for any language. File handling helps you to store data (any type of data) in a controlled manner like for cookies, for any type of configurations etc. A file represents a sequence of bytes on the disk where a group of related data is stored. File is created for permanent storage of data. The fopen() function is used to create a new file or to open an existing file.
General Syntax:
          *fp = FILE *fopen(const char *filename, const char *mode);
Here, *fp is the FILE pointer (FILE *fp), which will hold the reference to the opened(or created) file. Filename is the name of the file to be opened and mode specifies the purpose of opening the file. Mode can be of following types, 

✓ r - opens a text file in reading mode
✓ w - opens or create a text file in writing mode.
✓ a - opens a text file in append mode
✓ r+ - opens a text file in both reading and writing mode
✓ w+ - opens a text file in both reading and writing mode

✓ a+ - opens a text file in both reading and writing mode
✓ rb - opens a binary file in reading mode
✓ wb - opens or create a binary file in writing mode
✓ ab - opens a binary file in append mode
✓ rb+ - opens a binary file in both reading and writing mode
✓ wb+ - opens a binary file in both reading and writing mode
✓ ab+ - opens a binary file in both reading and writing mode 

Program :-

Source code :

 

/* Program to create edit copy of file */
# include <stdio.h>
#include <conio.h>
void main( )
{
       FILE *fp ;
       char sub[50], temp[20];
       int s, t;
       clrscr( );
       fp=fopen(“Exam.txt”,”w+”);
       printf( “Enter seat number and subject of the candidate : ” ) ;
       scanf(“%d %s”, &s, &sub);
       printf(“ Seat No \t Subject \n”);
       rewind(fp);
       fscanf(fp,”%s %d”, &temp, &t);
       printf(“%s %d”, temp, t);
       fclose(fp) ;
       return 0;
}

Output :-  

Enter Seat number and Subject of the student : 2001 Chemistry Seat number       Subject 2001                  Chemistry