Educator

Introduction to File I/O

• File I/O typically involves three steps:
  1. Open a connection to a file
  2. Perform read/write operations on the file
  3. Close the connection to the file
• In order to read from or write to a file from PHP, the user account under which the PHP interpreter runs must have the appropriate read/write permissions on the file, depending on the desired operation.
• fopen() is used to open a file. You must specify whether you wish to open the file for reading, writing, or both. This is done using the function's access mode parameter.
• fopen() returns a file handle, which represents a connection to an opened file. The file handle is a special PHP data type known as a resource.
• File paths should always be specified using forward-slashes (/) as the path separator because it maximizes the portability of your code.
• Data in a file is accessed using a file pointer, which is a cursor used to keep track of the current character being accessed in a file.
• When opening a file with fopen() using ‘r’ as the access mode, the file is opened for reading with the file pointer placed at the beginning of the file.
• fgets() reads the contents of the current line of a file and advances the file pointer to the beginning of the next line.
• feof() returns TRUE if a file pointer’s current position is at the end of the file (EOF).
• fclose() is used to close the connection to an open file by passing it the file handle of the open file.
• trim() is used to strip any whitespace from the beginning or end of a string.
• Additional Resources:
  • Function Reference - fopen()
  • Function Reference - fgets()
  • Function Reference - feof()
  • Function Reference - fclose()
  • Function Reference - trim()