This document discusses file input and output (I/O) in C programming. It defines a file as a connection of bytes stored in secondary storage that can be processed by programs. There are two types of files: text files containing ASCII characters and binary files containing non-ASCII data like images, audio, and video. The document outlines the steps to process a file in C using library functions like fopen() to open a file, fclose() to close it, and fflush() to clear buffers. It also describes various functions for character, string, formatted, and random access I/O.

1. Programming in
C

2. What is File?
File is a connection of bytes stored in our secondary device. We
frequently use these files for storing different information
which can be process by our program. So in order to store the
information permanently we need to use these files.
Bytes
---------
---------
file
Header file
There are two type of Files :
• Text Files(contains ASCII)
• Binary Files(contains Non- ASCII)(E.g.- audio, video, pictures)

3. Steps in Processing a File
1. Create the stream via a pointer variable using the
FILE structure:
FILE *p;
2. Open the file, associating the stream name with the
file name.
3. Read or write the data.
4. Close the file.

4. Library Functions For Files I/O
Different library functions are used for files input
& output. These routines are used to open ,
close, read ,write file using formatted
Input/output.
1. fopen()
2. fclose()
3. fflush()

5. • fopen() : This function is used to open a file for
formatted I/O & to associate a stream with that
file. A stream is a destination of data. It may be
buffer in the memory of a file or some hardware
device such as a port.
Syntax: FILE *fptr
fptr=fopen(“file name", "mode”);

6. Modes used for opening a file:
• r - open for reading an existing file.
• w - Creating a new file for writing only. If file with same
name exits, it will be overwritten.
• a - Open an existing file & append the contents at the end
of that file. If file does not exist, it will create a new file.
• r+ - Open files for update(reading & writing).
• W+ - Open Or create file for update. Discard any
previous data.
• a+ - Open or create file for update Write after any
previous data.

7. • fclose() : This function is used to close the file.
Syntax: int fclose(fptr);
• fflush() :This function used for clearing the buffer
before closing the file. It flushes the currently
available pending data of files. All the output units
will be flushed, in case the parameter is NULL. It is
useful when some set of writes has completed
before, like responding to a request.
Syntax: int fflush(file* stream)

8. Character Input/output
1. fputc()
2. fgetc()
• fputc() : fputc writes a single character or constant
to the output stream. It returns at end of the file on
failure.
Syntax: int fputc(c,fptr);
• fgetc() : fgetc is used to abstract a single character
from any given file.
Syntax: int fgetc(fptr);

9. String Input/output
1. fputs()
2. fgets()
• fputs() : This function is used to writing
a string to a file.
Syntax : int fputs(sptr,fptr);
• fgets() : This function is used to take
strings to the file.
Syntax : a=fgets(str,int n,fptr);

10. Formatted Input/output
1. fprintf()
2. fscanf()
• fprintf()- Data is written to a file using this
function. fprintf() is very similar to printf().
Syntax: int fprintf(fptr,””format-string”,items);
• fscanf - Data is read from a file using fsanf().
fscanf() is very similar to scanf().
Syntax: int fscanf(fptr, “format-string”,items);

11. Random Access to file
• fseek() : This function is used to place our
cursor to a certain position in our file.
Syntax : fseek(fptr,offset,mode);
Modes:
0(SEEK_SET)represents the beginning of the
file.
1(SEEK_CUR)represents the current position of
the file.
2(SEEK_END)represents the end of the file.