En anglais

Text by the numbers

Informatique · Programmation · de 15 à 16 ans

Nom ______________________ Date ____________

What does a slice copy?
- Characters from its start through its stop
- Characters from its start up to, but not including, its stop
- Only the character at its stop
In most languages, what seat number does the first character of a string sit in?
- 0
- 1
- -1
len() counts spaces as well as letters.
En entourer un : Vrai Faux
name holds "Ada". What does name[-1] give?
- A
- d
- a
phone holds "02079460018". What does phone[3:7] give?
- 79460
- 7946
- 0794
How many characters are in "Hi Jo"?
Réponse : ______________
A word has length 5. Which test keeps a loop on real seats only?
- seat < 5
- seat <= 5
- seat < 4
A program reads word[4] from a 4-character word and crashes. What went wrong?
- The word is too short for len()
- Seat 4 holds an invisible space
- Seats run 0 to 3, so seat 4 does not exist

Corrigé

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Characters from its start up to, but not including, its stop · A slice starts at its first number and stops just before its last number.
0 · Counting starts at 0, so the first character lives at index 0.
Vrai · Every character counts toward the length, including spaces.
a · -1 counts back from the end, so it grabs the last character.
7946 · Seats 3, 4, 5 and 6 hold 7, 9, 4 and 6, and the slice stops before seat 7.
5 · Two letters, a space, then two letters make 5 in total.
seat < 5 · Seats run 0 to 4, so stopping below 5 visits each real seat once.
Seats run 0 to 3, so seat 4 does not exist · With length 4 the seats are 0, 1, 2 and 3. Reaching for seat 4 is one too far.