Exam 010-160 topic 1 question 67 discussion

? The preceding item is optional and will be matched, at most, once. * The preceding item will be matched zero or more times. The answer is A. 100%. It is asking zero or ONE time.

I'm assuming the question was not clear or either a tricky question, but this is what I found and would stick with "A" being the correct answer (\? Matches zero or one occurrence of the previous character ). * would be zero or more. Source: https://www.guru99.com/linux-regular-expressions.html

The operator that matches the preceding character either zero or one time is the question mark (?) For example, the regular expression colou?r matches both “color” and “colour”.

? is used when it is zero or ONE, and * is used for zero or MORE. Thus ? is the answer, since it more precisely matches the question asked. See https://www.geeksforgeeks.org/how-to-use-regular-expressions-regex-on-linux/# and go to 7.

The question asks "IN A REGULAR EXPRESSION" If you read any documentation, you'll see that the correct answer is A (I mean, the "?")

https://tldp.org/LDP/Bash-Beginners-Guide/html/sect_04_01.html

A is the correct

B is the correct answer. Table 4-1. Regular expression operators Operator Effect . Matches any single character. ? The preceding item is optional and will be matched, at most, once. * The preceding item will be matched zero or more times. + The preceding item will be matched one or more times. {N} The preceding item is matched exactly N times. {N,} The preceding item is matched N or more times. {N,M} The preceding item is matched at least N times, but not more than M times. - represents the range if it's not first or last in a list or the ending point of a range in a list. ^ Matches the empty string at the beginning of a line; also represents the characters not in the range of a list. $ Matches the empty string at the end of a line. \b Matches the empty string at the edge of a word. \B Matches the empty string provided it's not at the edge of a word. \< Match the empty string at the beginning of word. \> Match the empty string at the end of word.

Correct answer is B

Which operator in a regular expression matches the preceding character either zero or one time?

B is correct

The asterisk is used to find something that is repeated 0 or more times. For example, using the expression "[a-zA-Z] \ d *" it will be possible to find both "H" and "H1", "H01", "H100" and "H1000", that is, a letter followed by a undefined number of digits.

I would go with B. Literally google it and you will find it.

B is the correct answer , ? in cammande line mean that is one character , but * mean a one or r zero or more in the same time