## Chapter 7 — Sam is a substring, not a directory ### Lesson map Lesson 07. Map, example, EX053. ```mermaid flowchart TD K["Key text form owner Sam"] --> T{"Is the character sequence Sam inside it?"} T -->|Yes| F["Failure label"] T --> Q{"Did the script open a staff list?"} Q -->|No| R["The test is text only"] ``` The letters decide. A person record is not consulted. ### Logical drawing ```text tested string form owner Sam sought sequence Sam case capital S not consulted a staff list a deputy named later ``` ### Learning outcomes After this chapter, you should be able to: 1. Point at the characters the test searches. 2. Separate that search from a staff lookup. 3. Refuse a deputy's name that the script never stored. ### 7.1 The operator looks for characters. It does not know who Sam is. `"Sam" in d` is true when the key contains the capital letters S, a, m in that order. The key `form owner Sam` contains them, so the test is true. The same test on `coordinator inbox` is false, which is why that line depends on the length test instead. The comparison is case-sensitive. A key written `form owner sam` would not satisfy this particular search. This file does not contain that lowercase key. The script has no list of staff, no holiday calendar, and no field for a deputy. Sam Okafor is the volunteer in the case notes. The letters in the key happen to spell his given name. That coincidence is not a query. When the notes later say a second person should own the form, those notes do not edit `d`, and they do not remove the failure label from the embedded print. The lab still shows the single owner it was given. A key such as a word that merely contained those three letters would also trip the test. This run has no such extra key, and this chapter does not add one. The limit stands: the flag is a text test, not an identity check. | Object | Role | |---|---| | `form owner Sam` | The key that contains the sequence | | `"Sam" in d` | A case-sensitive character test | | A deputy | Prose, not a variable | | A staff directory | Absent from the file | ### 7.2 Worked example | Offered sentence | What the file supports | Decision | |---|---|---| | "The form line trips because the key contains Sam." | The substring test | Keep | | "The inbox key does not contain that sequence." | Length is its reason | Keep | | "The script looked Sam up and found he is on holiday." | No directory and no date | Refuse | | "Naming a deputy clears the printed flag." | The print is unchanged | Refuse | > **Synthetic case.** The key is a string in a classroom list. ### Errors and limits Do not promote a character test into a personnel decision. ### Apply - **EX053 — Substring.** What makes `form owner Sam` a failure when it has only one source, and does the script store a deputy? *Rubric:* 3 = the key contains the capital sequence Sam; the length test is false for that one name; no staff list and no deputy are stored;; 2 = the flag is a character test and the deputy is absent;; 1 = the name only;; 0 = none. ### Continue studying — lesson 07 (chapter 07 of 20) [← Chapter 06](#ch-06) · [Course chapter index](../SUBJECTS.md) · [Chapter 08 →](#ch-08) Continue to the next authored lesson. ## Worked answers **EX053.** The key contains the capital sequence Sam, and the length test is false for that single name. The script stores no staff list and no deputy.