How can I process several selected text files without changing their originals?

Keep the input selection narrow: write down the exact paths you want to process rather than scanning a folder. Open each selected file in read mode, perform the same check, and save the outcome in a separate results list. The example below counts records yielded by the CSV reader and records a missing path distinctly. It does not create or modify files; results exist only in memory until your program ends.

import csv

paths = [
    "samples/january.csv",
    "samples/february.csv",
    "samples/march.csv",
]

results = []

for path in paths:
    try:
        with open(path, "r", newline="") as file:
            row_count = sum(1 for _ in csv.DictReader(file))
        results.append({"path": path, "status": "ok", "rows": row_count})
    except FileNotFoundError:
        results.append({"path": path, "status": "missing"})

for result in results:
    print(result)

Python’s documented CSV pattern opens a named input with open(..., newline='') and reads it with csv.reader or csv.DictReader [S1]. The explicit path list, result collection, and missing-file status are application logic built around that pattern. Replace the sample paths with your own selected paths.

Here, the count is the number of records yielded by csv.DictReader(file). To use a different repeatable check, replace the sum(...) expression with your own logic while leaving the path loop and result handling intact. Decide what counts as a passing result before processing the batch, and make that outcome explicit in each result object. The example is intentionally simple: it does not validate whether the files have the right columns or whether their contents are meaningful.

The try block adds an ok result only after the file has been opened and the check has completed. If opening the selected path raises FileNotFoundError, the except block adds a missing result instead, with no row count. That keeps the status visible without pretending the file contained zero records. When you review the printed results, count only entries whose status is ok; investigate or correct paths marked missing before relying on a complete batch. The example handles missing paths specifically; it does not label every other possible problem as “missing.”

Yes. The shown version keeps results in the results list and prints them; it never opens an input for writing. If you later want a report file, choose a separate output path that is not one of the selected inputs, and write the results there deliberately. This example does not add that step, so it does not write a report file. Before running, check that the path list contains only intended inputs and that any output destination you add is distinct.