Array methods (Sort, Reverse, IndexOf) in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Array.Sort() method do in C#?

It arranges the elements of an array in ascending order (from smallest to largest).

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How does Array.Reverse() affect an array?

It reverses the order of the elements in the array, so the last element becomes first and the first becomes last.

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What does Array.IndexOf(array, value) return if the value is not found?

It returns -1 to indicate the value is not present in the array.

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Can Array.Sort() be used on arrays of strings in C#?

Yes, it sorts strings alphabetically (lexicographically) in ascending order.

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If you want to find the position of the first occurrence of a value in an array, which method do you use?

Use Array.IndexOf() to get the index of the first matching element.

What will Array.Sort() do to the array {3, 1, 4, 2}?

A Do nothing

B Reverse it to <code>{2, 4, 1, 3}</code>

C Return the index of 3

D Sort it to <code>{1, 2, 3, 4}</code>

Array.Sort() arranges elements in ascending order.

What does Array.Reverse() do to {"a", "b", "c"}?

A <code>{"c", "b", "a"}</code>

B <code>{"a", "b", "c"}</code>

C <code>{"b", "a", "c"}</code>

D <code>{"a", "c", "b"}</code>

It reverses the order of elements.

What does Array.IndexOf(array, value) return if value is not in the array?

A 1

B -1

C 0

D Throws an error

Returns -1 to show the value was not found.

Which method would you use to find the position of the number 5 in an array?

A Array.IndexOf()

B Array.Sort()

C Array.Reverse()

D Array.Clear()

Array.IndexOf() finds the index of a value.

After calling Array.Sort() on {"dog", "cat", "bird"}, what is the order?

A <code>{"bird", "dog", "cat"}</code>

B <code>{"dog", "cat", "bird"}</code>

C <code>{"bird", "cat", "dog"}</code>

D <code>{"cat", "dog", "bird"}</code>

Strings are sorted alphabetically in ascending order.

Explain how you would use Array.Sort(), Array.Reverse(), and Array.IndexOf() in a C# program.

Think about sorting a list, then reversing it, and searching for an item.

What happens if you try to find the index of a value that does not exist in the array using Array.IndexOf()?

Consider how to check if a value is missing.