C# APIs

Question 1

Determine the length of a List<>

Answer 1

List.Count() does not modify

Question 2

Add ab item to the end of a List<>

Answer 2

List.Add() in place modification, does not return

Question 3

index the i’th element of a List

Answer 3

List[i] returns the value but also allows modification or List.ElementAt(i) returns the value

Question 4

Remove element from List at i

Answer 4

List().RemoveAt(i), in place modification

Question 5

Reverse a List

Answer 5

List.Reverse() in place modification, returns void

Question 6

Given a List, merge all of the string elements into a single string

Answer 6

String.Join(“ “, List())

Question 7

Copy a List to a new T[]

Answer 7

List.ToArray()

Question 8

Given List, find the first occurrence of someT, start searching at index idx

Answer 8

List.IndexOf(someT, idx)

Question 9

Given List append another List to the end of it

Answer 9

List.Append(List otherList)

Question 10

Given Dictionary, determine if the key someKey exists

Answer 10

Dictionary.ContainsKey(someKey)

Question 11

Given Dictionary determine if someValue exists

Answer 11

Dictionary.ContainsValue(someValue)

Question 12

Return all of the keys in a dictionary as an IEnumerable

Answer 12

Dictionary.Keys

Question 13

Loop over all of the keys in a Dictionary

Answer 13

foreach (int key in Dictionary.Keys)

Question 14

Given a String, replace all instances of char1 with char2

Answer 14

String.Replace(char1, char2)

Question 15

Given a String, replace all instances of string1 with string2

Answer 15

String.Replace(string1, string2)

Question 16

Given a someChar which represents a number e.g. ‘1’, ‘2’, ‘3’

Get the numeric value of that char

Answer 16

Char.GetNumericVBalue(someChar)

.GetNumericValue is a static member method of the Char class

Question 17

Given someString, convert to an int

Answer 17

int32.Parse(someString)

Question 18

Given someString, get the substring of length L from idx1 to idx1 + L

Answer 18

someString.Substring(idx1, L)

Question 19

Given someString, insert otherString starting at index idx

Answer 19

someString.Insert(idx, otherString)