We all know that many information are required to be written or read from an auxiliary memory device .These type of information is stored on the memory device in the form of a data file. Thus, data file allows us to store information permanently, and to access and alter that information at the time of necessity. If there were no such data files there would be no provision for storing, editing and retrieving such information. Thus for the same purpose in C language, an extensive set of library functions are available for creating and processing these files. There are mainly two major categories of data files and they are as follows:
- Stream – Oriented (or standard) data files
- System – Oriented (or low-level) data flies
The System- oriented data files are divided into two categories they are
- i) Text Files:
- consists of consecutive characters
- These characters can be interpreted as individual data items, or as components of strings or numbers.
Ii) Unformatted data files:
- organizes data into blocks containing contiguous bytes of information
- These blocks represent more complex data structure, such as array and structures.
System- oriented data files:
- are more closely related to the computer’s operating system
- more complicated to work with
- A separate set of procedures, library functions are required to process these files
Here our study will be mainly focused only on Stream- oriented data files.
The C file system is composed of several interrelated functions. The most common of these are shown below. They require the header fie stdio.h to be included.
fopen( ) opens a file
fclose( ) closes a file
putc( ) write a character to a file
fputc( ) same as putc( )
getc( ) reads a character from file
fgetc( ) same as getc( )
fgets( ) reads a string from a file
fputs( ) writes a string from file
fseek( ) seeks to a specified byte in a file
ftell( ) returns the current file position
fprintf( ) is to a file what printf() is to console
fscanf( ) is to a file what scanf() is to console
feof( ) return true if end-of- file is reached
ferror( ) return true if an error has occurred
rewind( ) resets the file position indicator to the beginning
remove() erases a file
fflush( ) flushes a file