Files

    Find the output of following C program

         

1.  #include<stdio.h>

int main()

{

FILE *fptr;

unsigned char ch;

fptr=fopen("ss.txt","w") ;   

fclose(fptr);

return 0;

}

2.  #include<stdio.h>

int main()

{

FILE *fptr;

unsigned char c;

fptr=fopen("ss.txt","r") ;   

c=getc(fptr);

while(c!=EOF)

{

 printf("%c",c);

 c=getc(fptr);

}

fclose(fptr);

return 0;

}

3.  #include<stdio.h>

int main()

{

FILE *fptr;

char c;

fptr=fopen("ss.txt","r") ;   

c=getc(fptr);

while(c!=EOF)

{

 printf("%c",c);

c=getc(fptr);

}

fclose(fptr);

return 0;

}

4.  #include<stdio.h>

int main()

{

FILE *fptr; 

int ch;

fptr=fopen("ss.txt",'w+');

while((ch=fgetc(fptr))!=EOF)       

putchar(ch) ; 

fclose(fptr) ;

return 0;

}

5.  #include<stdio.h>

int main()

{

FILE *fptr; char str[30]; 

fptr=fopen("ss.txt","r");  

while(fgets(str,30,fptr)!=EOF)      

puts(str);

return 0;

}

6.  #include<stdio.h>

int main()

{

char c;

FILE *f1;

f1=fopen("ss.txt","r");

c=getc(f1);

while(c!=EOF)

{

printf("%c",c);

fseek(f1,1,1);

c=getc(f1);

}

return 0;

}

ANSWER

1.    This will carat an empty file named as ss.txt

2.    It goes infinite loop on printing garbage values on the screen.

Hints-ASCII for EOF character is -1

3.    It will print the content of file “ss.txt” if the file doesn’t exist in the current folder produce run time error.

4.    error   (w+ should be written as a string, like “w+”)

5.    Last line of the file “ss.txt” will be displayed infinitely.

Hint-fgets() does not return NULL on end of file or on error, not EOF. The contents of the who file will be displayed and then fgets( ) will return NULL at the end of file, but the loop condition checks for EOF.

6.    It will read the alternate character from the file ”ss.txt” and print on screen.