Opening and Creating a file in different modes || Files and File handling || Bcis notes

Opening and Creating a file in different modes

C File management

A File can be used to store a large volume of persistent data. Like many other languages ‘C’ provides following file management functions,

  1. Creation of a file
  2. Opening a file
  3. Reading a file
  4. Writing to a file
  5. Closing a file

Following are the most important file management functions available in ‘C,’
function purpose
fopen ()                                                                      Creating a file or opening an existing file
fclose ()                                                                      Closing a file
fprintf ()                                                                    Writing a block of data to a file
fscanf ()                                                                     Reading a block data from a file
getc ()                                                                         Reads a single character from a file
puts ()                                                                        writes a single character to a file
get ()                                                                          Reads an integer from a file
puts ()                                                                        Writing an integer to a file
fseek ()                                                                       Sets the position of a file pointer to a specified location
ftell ()                                                                         Returns the current position of a file pointer
rewind ()                                                                   Sets the file pointer at the beginning of a file

In this tutorial, you will learn-

How to Create a File
How to Close a file:
Writing to a File
fputc() Function:
fputs () Function:
Reading data from a File
Interactive File Read and Write with getc and put

How to Create a File
Whenever you want to work with a file, the first step is to create a file. A file is nothing but space in a memory where data is stored.

To create a file in a ‘C’ program following syntax is used,

FILE *fp;
fp = fopen (“file_name”, “mode”);

In the above syntax, the file is a data structure which is defined in the standard library.

fopen is a standard function which is used to open a file.

If the file is not present on the system, then it is created and then opened.
If a file is already present on the system, then it is directly opened using this function.
fp is a file pointer which points to the type file.

Whenever you open or create a file, you have to specify what you are going to do with the file. A file in ‘C’ programming can be created or opened for reading/writing purposes. A mode is used to specify whether you want to open a file for any of the below-given purposes. Following are the different types of modes in ‘C’ programming which can be used while working with a file.

File Mode Description
r                                                              Open a file for reading. If a file is in reading mode, then no data is deleted if a                                                                          file is already present on a system.

w                                                             Open a file for writing. If a file is in writing mode, then a new file is created if a                                                                      file doesn’t exist at all. If a file is already present on a system, then all the data                                                                        inside the file is truncated, and it is opened for writing purposes.
an Open a file in append mode. If a file is in append mode, then the file is                                                                                opened. The content within the file doesn’t change.

r+                                                           Open for reading and writing from beginning

w+                                                          Open for reading and writing, overwriting a file

a+                                                           Open for reading and writing, appending to file
In the given syntax, the filename and the mode are specified as strings hence                                                                          they must always be enclosed within double-quotes.


#include <stdio.h>
int main() {
FILE *fp;
fp = fopen (“data.txt”, “w”);

File is created in the same folder where you have saved your code.

These are the conceptual notes of Opening and Creating a file in different modes
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