The code

Straight from labs/course-3-python/10_copy_file.py, unchanged.

"""Experiment 10: Copy the contents of one file into another file.

Syllabus: Course 3, Unit 4 -- file handling.
"""

SOURCE = "source.txt"
TARGET = "target.txt"

# Step 1: Write the source file
with open(SOURCE, "w") as fh:
    fh.write("Line 1: Python file handling\n")
    fh.write("Line 2: reading and writing\n")
    fh.write("Line 3: Data Science Major\n")

# Step 2: Copy it line by line
# Copy line by line so the program works on files too large to hold in memory.
lines_copied = 0
with open(SOURCE, "r") as src, open(TARGET, "w") as dst:
    for line in src:
        dst.write(line)
        lines_copied += 1

print(f"Copied {lines_copied} lines from {SOURCE} to {TARGET}\n")

# Step 3: Print the copy
with open(TARGET, "r") as fh:
    print(f"Contents of {TARGET}:")
    print(fh.read())

# Step 4: Check that the two files match
# Verify the two files now match.
with open(SOURCE) as a, open(TARGET) as b:
    print("Files are identical" if a.read() == b.read() else "Files DIFFER")

Where this sits

One experiment from the Python Programming and Data Structures lab. The rest of them, and the theory behind this one, are on the lab page.