This document discusses file management in 3 paragraphs. It describes what a file is, common file operations like naming, opening, reading, writing and closing files. It explains different modes for opening files like read, write and append and provides examples of opening files. It also gives examples of C programs that illustrate reading a file using getc(), reading a line using fgets(), and writing characters and strings to a file using fputc() and fputs().

1. Chapter – 9 File Management

2.  File
• File is a place in the disk where a group of related data is stored.
 File Operations
• naming a file
• opening a file
• reading data from file
• writing data to a file
• closing a file.

3.  Naming of File
• String of characters that make up a valid filename for OS
• May contain two parts
• Primary
• Optional period with extension
• Examples: a.out, prog.c, temp, text.out

4.  Opening file
• fp
• contains all information about file
• Communication link between system and program
• Mode can be
• r open file for reading only
• w open file for writingonly
• a open file for appending (adding) data
FILE *fp;  variable fp is pointer to type FILE
fp = fopen(“filename”, “mode”);  opens file with name filename , assigns identifier to fp

5.  Different modes
1. Writing mode
• if file already exists then contents are deleted,
• else new file with specified name created
2. Appending mode
• if file already exists then file opened with contents safe
• else new file created
3. Reading mode
• if file already exists then opened with contents safe
• else error occurs.
FILE *p1, *p2;
p1 = fopen(“data”,”r”);
p2= fopen(“results”, w”);

6.  Additional modes
• r+ open to beginning for both reading/writing
• w+ same as w except both for reading and writing
• a+ same as ‘a’ except both for reading and writing

7.  File handling functions

8. program to illustrate reading files contents
#include<stdio.h>
#include<conio.h>
void main()
{
FILE *fp;
char ch,fname[50];
printf("enter the file name");
gets(fname);
if((fp= fopen(fname,"r")) == NULL){
printf("can't open file");}
do{
ch = getc(fp);
putchar(ch);
}while(ch != EOF);
fclose(fp);
getch();
}

9. program to illustrate the use of fgets( )
#include<stdio.h>
#include<stdlib.h>
int main()
{
FILE *fp;
char str[80],fname[50];
printf("enter the name");
gets(fname);
if((fp=fopen(fname,"r"))==NULL)
{
printf("cant open file");
}
if(fgets(str,12,fp)!=NULL)
printf("%s",str);
fclose(fp);
getch();
}

10. program to illustrate the use of fputc ( ) and
fputs( )
#include<stdio.h>
#include<stdlib.h>
void main()
{
FILE *fp;
fp = fopen("10_1.txt","w+");
if(fp==NULL)
{
printf("cant open file");
}
fputc('f',fp);
fputs("How are you",fp);
fclose(fp);
getch();
}