File Handling: Reading from and Writing to Text Files

This lesson covers file handling as required by OCR J277 Section 2.3. File handling allows programs to read data from files and write data to files, so that information persists even after the program has finished running. OCR uses specific pseudocode syntax for file operations that you must know for the exam.

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Why Use File Handling?

When a program ends, all data stored in variables is lost. File handling allows programs to:

• Save data permanently (e.g. high scores, user settings, logs)
• Read data that was previously saved
• Process large amounts of data stored in files
• Share data between different programs

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OCR File Handling Pseudocode

OCR uses specific functions for file handling:

Function	Purpose
openRead(filename)	Opens a file for reading
openWrite(filename)	Opens a file for writing (creates new or overwrites)
readLine()	Reads the next line from the file
writeLine(data)	Writes a line of data to the file
close()	Closes the file
endOfFile()	Returns true if the end of the file has been reached

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Reading from a File

OCR Pseudocode:

myFile = openRead("students.txt")

while NOT myFile.endOfFile()
    line = myFile.readLine()
    print(line)
endwhile

myFile.close()

Python:

# Method 1: Using with statement (recommended)
with open("students.txt", "r") as my_file:
    for line in my_file:
        print(line.strip())  # strip() removes the newline character

# Method 2: Reading all lines into a list
with open("students.txt", "r") as my_file:
    lines = my_file.readlines()
    for line in lines:
        print(line.strip())

Reading Line by Line

myFile = openRead("data.txt")
firstLine = myFile.readLine()
secondLine = myFile.readLine()
print(firstLine)
print(secondLine)
myFile.close()

with open("data.txt", "r") as my_file:
    first_line = my_file.readline().strip()
    second_line = my_file.readline().strip()
    print(first_line)
    print(second_line)

OCR Exam Tip: Always remember to close() the file after reading or writing in OCR pseudocode. In Python, using the with statement automatically closes the file, which is considered best practice. In the exam, if writing pseudocode, you MUST include close().

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Writing to a File

OCR Pseudocode:

myFile = openWrite("output.txt")
myFile.writeLine("Hello, World!")
myFile.writeLine("This is line 2")
myFile.writeLine("This is line 3")
myFile.close()

Python:

with open("output.txt", "w") as my_file:
    my_file.write("Hello, World!\n")
    my_file.write("This is line 2\n")
    my_file.write("This is line 3\n")

Important: openWrite Overwrites!

When you use openWrite(), if the file already exists, its contents are completely replaced. This is important to remember — you could accidentally lose data.

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