JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III WEB TECHNOLOGIES Previous Question Paper (February/March - 2022 - R16)

PHP provides a comprehensive set of built-in functions to perform file handling operations, allowing developers to create, read, write, append, and delete files on the server. The primary operations are as follows:

1. Opening a File (fopen): The fopen() function is used to open a file or URL. It requires two parameters: the filename and the mode (e.g., 'r' for read-only, 'w' for write-only, 'a' for append). It returns a file pointer resource on success or false on failure.
2. Reading a File: Several functions exist for reading content. fread() reads a specified number of bytes from an open file. fgets() reads a single line, while fgetc() reads a single character. file_get_contents() is a convenient function that reads the entire file into a string without needing to manually open or close it.
3. Writing to a File: The fwrite() function is used to write data to an open file stream. It takes the file pointer and the string to be written as arguments. Alternatively, file_put_contents() can be used to write data to a file in a single operation, which automatically handles opening and closing the file.
4. Closing a File: The fclose() function is essential to release the system resources associated with an open file pointer. It is best practice to close files immediately after operations are completed.
5. File Checking and Deletion: PHP provides utility functions like file_exists() to verify if a file exists, filesize() to determine the file size, and unlink() to delete a file from the server filesystem.
6. File Locking: To prevent data corruption during concurrent write operations, flock() is used to set an advisory lock on the file, ensuring that only one process can modify the file at a time.