428 Programming and Data Structures
Exam ple
fcloseall ()
This function closes all the open files and returns number of files closed. It does not require any
argument.
13.4 FILE I/O
I. f p r i n t f () This function is used for writing characters, strings, integers, floats etc. to the file. It
contains one more parameter that is file pointer, which points the opened file. Here is a program that
illustrates the use of f p r in t f ( ) functions.
13.7 Write a program to open a text file and write some text using fprintfO function. Open
the file and verify the contents.
# include <stdio.h>
# include <conio.h>
main()
{
FILE *fp ;
char t e x t [30] ;
fp=fopen( "T ext. t x t " , "w” ) ;
c l r s c r ( ) ;
printf ("Enter Text Here
gets (text);
fprintf (fp,"%s",text);
fclose(fp);
I
OUTPUT:
Enter Text Here: Have a nice day.
Explanation In the above program f prin t f () functions writes the string to the file pointed by f p.
The string is collected through gets ( ) function into character array name [3 0 ].
2. f scanf ( ) This function reads character, strings, integer, floats etc. from the file pointed by file
pointer. A program is illustrated below based on this.
13.8 Write a program to enter data into the text file and read the same. Use "w +" file mode.
Use fscanfO to read the contents of the file.
# include <stdio.h>
# include <conio.h>
main()
{
FILE *fp;
char text [15] ;
int age;
fpsfopen ("Text. txt", "w+") ;
clrscr();
Files 429
printf ("N a m etAG E n");
scanf("%s %d",textf&age);
fprintf (fp,"%s %d", text,age);
printf ("Nam et AGEti ");
fscanf(fp/'%s %df/,text,&age);
printf ("% st% dn", text,agt);
fclose(fp);
I
OUTPUT:
Name
AGE
AMIT
12
Name
AGE
AM IT 12
Explanation In the above program f scanf () reads the data from the file named " t e x t . t x t " .
3. g e tc ( ) This function reads a single character from the opened file and moves the file pointer. It
returns EOF, if end of file is reached.
13.9 Write a program to read the contents of the file using getc(0 function.
# include <stdio.h>
# include <process.h>
# include cconio.h>
void mainO
{
FILE *£;
char c;
clrsc rO ;
f=fopen("list.txt","r");
if(f==NULL)
{
printf(‘‘
Cannot open file");
exit(l);
I
while <(c=getc(f))!=EOF)
printf ("%c",c);
fcloseff);
I
OUTPUT:
aman
akash
amit
ajay
ankit
430 Programming and Data Structures
Explanation In the above program the ge tc () reads character from the file " li s t . txt". Some text is
to be written before reading this file.
4. putc ( ) This function is used to write a single character into a file. If an error occurs it returns EOF.
13.10 V/rite a program to write some text into the file using putcO function.
# include <stdio.h>
# include <conio;h>
void mainO
{
int c;
FILE * fp ;
clrscr ();
printf ("n Enter Few Words to Exitn");
fp=fopen("words.doc", ”w ");
while ( (c=getchari))!='*')
putc(c,fp);
fcloseifp);
}
OUTPUT:
Enter Few Words to Exit
This is saved into the file *
Explanation The putc () function writes character reads through getchar () in the file "words. doc".
The user should enter ' * ' to stop reading character.
5. f g e tc ( ) This function is similar to g e t c () function. It also reads a character and increases the
file pointer position. If any error or end of file is reached it returns EOF.
13.11 Write a program to read a 'C' program file and count the following in the complete
program.
Ibtal number of statements.
Total number of included files.
Total number of blocks & brackets.
#include <stdio.h>
finclude <conio.h>
nain()
<
PILE * f s ;
int i*0/x /y,CBO,sb>0,b>>0;
clrscr()j
fs=fopen(“PRG2. C", "r");
if(fs=**NILL)
Files 431
{
printf ("n File opening error.");
exit(l);
while ((x=fgetc(fs))!=EOF)
r
switch(x)
{
case :
C++;
break;
case T :
sb++;
break;
case T :
b++;
break;
case '# ':
«++;
break;
I
fcloseffs);
printf ("n Summary o f 'C Program
");
printf ("=========================");
printf ( “
Total Statements : %d ",c+i);
printf ( “
Include Statements : %d",i);
printf C'n Total Blocks II :% d ",sb);
printf ("n Total Brackets ( ) : %d",b);
printf rM============“ ============">;
}
OUTPUT:
Total Statements : 25
Include Statements : 4
Total Blocks {) : 5
Total Brackets 0 : 25
Explanation In the above program the f g etc ( ) function reads the file "p rg 2 . c" character by
character and returns the read character to variable ' x ' . The variable ' x ' is then passed to switch ()
case. Depending upon the contents of the variable 'x ' respective counter is increased in each case
statement. Thus, at last all summary is printed.
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