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a+ Opens a text file for both reading and writing. It creates the file if it
does not exist. The reading will start from the beginning but writing
can only be appended.

If you are going to handle binary files, then you will use the following access modes
instead of the above-mentioned ones:

"rb", "wb", "ab", "rb+", "r+b", "wb+", "w+b", "ab+", "a+b"

Closing a File
To close a file, use the fclose( ) function. The prototype of this function is:

int fclose( FILE *fp );

The fclose() function returns zero on success, or EOF if there is an error in closing the
file. This function actually flushes any data still pending in the buffer to the file, closes the file,
and releases any memory used for the file. The EOF is a constant defined in the header file
stdio.h.
There are various functions provided by C standard library to read and write a file,
character by character, or in the form of a fixed length string.

Writing a File
Following is the simplest function to write individual characters to a stream:

int fputc( int c, FILE *fp );

The function fputc() writes the character value of the argument c to the output stream
referenced by fp. It returns the written character written on success otherwise EOF if there is an
error. You can use the following functions to write a null-terminated string to a stream:
int fputs( const char *s, FILE *fp );

The function fputs() writes the string s to the output stream referenced by fp. It returns a
non-negative value on success, otherwise EOF is returned in case of any error. You can use int
fprintf(FILE *fp,const char *format, ...) function as well to write a string into a file. Try the
following example.
Make sure you have /tmp directory available. If it is not, then before proceeding, you
must create this directory on your machine.

#include <stdio.h>

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