Match literal and repeated characters
See this course’s project requirements
A checked extraction script for fictional equipment tags, dates and log lines, with a mismatch report and exact-match safety boundaries.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- A precise tag grammar with four checked cases.
- A segment-by-segment match explanation.
- A whole-input validation rule with a counterexample.
- An extracted log record with explicit string/number distinctions.
- A semantic date check separate from regex matching.
- A tested tag-and-log extraction tool with semantic limits.
Review and revise
Use these criteria to check your work and choose what to improve.
- The implementation or declared simulation follows the supplied contract and retains inspectable original inputs.
- Normal, boundary and rejected cases are recorded with expected versus observed results.
- The changed case has a correct explanation and does not rely on hidden state.
- The project includes source, outputs, instructions and honest tool, privacy and verification limits.
Want more background?
The idea in everyday life
The supplied TAG pattern is r"EQ-(?P<number>[0-9]{3})". Raw-string notation keeps backslashes literal when a pattern needs them.
A literal matches itself. A character class matches one member; a quantifier repeats that match. Use [0-9]{3} for exactly three ASCII digits rather than assuming every Unicode digit is accepted.
Match literal and repeated characters — original worked practice
A literal matches itself. A character class matches one member; a quantifier repeats that match. Use [0-9]{3} for exactly three ASCII digits rather than assuming every Unicode digit is accepted.
The supplied TAG pattern is r"EQ-(?P<number>[0-9]{3})". Raw-string notation keeps backslashes literal when a pattern needs them.
1. Step 1
Find the literal EQ- portion.
You should see: It requires those exact three characters.
This keeps the rule and its observable result together.
2. Step 2
Read [0-9] as one allowed digit.
You should see: It does not match letters.
This keeps the rule and its observable result together.
3. Step 3
Read {3} as an exact repetition count.
You should see: Three digit characters are required.
This keeps the rule and its observable result together.
4. Step 4
Trace EQ-120 through each pattern segment.
You should see: A segment-by-segment match explanation.
This keeps the rule and its observable result together.
What to finish
A segment-by-segment match explanation.
Watch for this
Using a wildcard dot where the identifier needs a literal dash and exactly three ASCII digits.
How can I tell I understand it?
Explain and demonstrate the required distinction: A literal matches itself. A character class matches one member; a quantifier repeats that match. Use [0-9]{3} for exactly three ASCII digits rather than assuming every Unicode digit is accepted. Show a changed input and the expected result without weakening this contract.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
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Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.
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Sources and further reading
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Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
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