file handling in c programming notes exam program

 Topics

• File handling in c
• Create a file in c
• Opening a file in c
• Reading a file in c
• Moving to a specific location in a file in c
• Closing file in c 

File Handling in c

So far we have gone through C program output is not stored anywhere. But there may be some situation where we need to store the work done so that we can use this stored data at a later time as and when required. C provides us the facility to store the data in a file using the concept of file handling / Data file handling . Different operations that can be performed on a file are:

1.  Creation of a new file (fopen with attributes as "a","a+",w" or "w+"
2. Opening an existing file (fopen)
3. Reading from file (fscanf or fgets)
4. Writing to a file (fprint or fputs)
5. Moving to a specific location in a file (fseek, rewind)
6. closing a file (fclose)

Fopen()

This function is used to open a file to perform operations such as reading, writing etc. In a C program, we declare a file pointer and use the function fopen() to open a file for performing various operations,

        For Example:

                               FILE *fp;

                               fp=fopen("filename","mode");

Here,

        fp -- is the file pointer tothe datatype FILE.

        filename-- is the name of the file with full path.

        mode-- mode in which file will be opened

Opening or Creating file in c

For opening a file , we use fopen() function with the required access modes. Some of the commonly used file access modes are mentioned below.

File opening modes in c

Mode               Description  

  r               Opens a text file in read mode.

 w              Opens a text file in write mode. 

 a               Opens a text file in append mode.

 r+             Opens a text file in read and write mode.

 w+           Opens a text file in read and write mode.

 a+            Opens a text file in read and write mode.

 rb             Opens a binary file read mode.

 wb            Opens a binary file write mode.

 ab             Opens a binary file append mode.

 rb+           Opens a binary file read and write mode

 wb+         Opens a binary file read and write mode

 ab+          Opens a binary file read and write mode

Closing a File (fclose function) in c

• The C library function fclose(FILE *fp) close the file. If we don't close use fclose() it may lead to loss of data.
• All buffers are flushed.
• int fclose(FILE *fp)
• This method return zero it the stream is successfully closed. On failure , EOF is retured.

Writing Data to File

C provide three in built-in function writing data in a file.

•     fputc()
•     fprintf()
•     fputs()

fputc() function in c 

fputc()  - The fputs() function is used to write a single character into file.

        For exam 

         #include<stdio.h>

         manin()

         {     FILE *fp;

            fp=fopen("file.txt","w"); //opening file

            fputs("a",fp); //writing single character into file

            fclose(fp); //closing file

            }

fprintf() function in c

fprintf()  - The function is used to write string into a file pointer by the file pointer.

      For exam

     {

        FILE *fp;

        fp=fopen("file.txt","w");

        fprinf(fp,"File healding in c programming");

        fclose()

        return o;

fputs function in c 

fputs()   -  The fputs() function is used to writes a line of characters into the file.

        For exam

        {

            FILE *fp;

            fp=fopen("file.txt","w");

            fputs(fp , "File heading in c programming");

            getch();

         }