File Handling

File handling in C allows you to work with files on your computer's file system. You can use C functions to perform various operations on files, such as:

• Creating new files
• Open a file
• Reading from files
• Writing to files

File Pointers

In C language, we need pointers to interact with files. We need to declare a file pointer to work with a file.

Opening a File

To open a file for reading and writing, we can use "fopen()" function. It returns a pointer to the targeted file.

In this example:

• "filename.txt" is the name of the file.
• "mode" specifies the mode in which we open the file.

Modes

1. "r" for reading.
2. "w" for writing.
3. "a" for appending.

Reading from a File

Reading a file in C can be done using the standard input/output library functions. To read data from a file, we use "fscanf()" or "fgets()" functions.

In this example:

• "stdio.h" library is used to access file related functions.
• We declare a pointer of FILE type to interact with the file.
• Now, we have opened the file using "fopen()" function in read mode.
• We use a while loop to read the file character by character using fgetc. The loop continues until the end of the file (EOF) is reached.
• We printed each character in while loop using "putchar".
• At the end, we close the file using "fclose()" function.

Writing to a File

To write data to a file, you can use functions like fprintf() or fputs().

In this example:

• "stdio.h" is used to access the file related operations.
• We declare FILE type pointer to interact with files.
• We opened the file using "fopen()" in write mode.
• Now we write data in file using "fputs()" function.
• Finally, we closed the file using "fclose()" function.

Appending to a File

Appending to a file is similar to writing to a file but we open file in append mode. In append mode, we add data to the end of the file, without overwriting the existing content.

In this example:

• stdio.h is used to access the file-related functions.
• We declare a FILE type pointer to interact with files.
• We open a file using "fopen()" function.
• We write data to the file using "fputs()" function.
• Finally, we close the file using "fclose()" function.