Getting sum from key value pair using List in C#

Question

I have following code

var list = new List<KeyValuePair<string, int>>();

list.Add(new KeyValuePair<string, int>("Cat", 1));
list.Add(new KeyValuePair<string, int>("Cat", 2));
list.Add(new KeyValuePair<string, int>("Rabbit", 4));

Now I am trying to pass "Cat" and I should get sum of these keys in a variable.If I pass Rabbit, pass only that number

How to get this ? thinking of for-each....

I don't know what you mean by "If Keys are not equal, pass only that number" — Dennis_E
– Dennis_E, Commented Feb 21, 2018 at 12:32
What's your call on this? Did you try anything? Did it work? What issue did you face? — Chetan
– Chetan, Commented Feb 21, 2018 at 12:33
I just thought about list and written code. Which is best? list or Dictionary — atc
– atc, Commented Feb 21, 2018 at 12:33
Use a real class instead of KeyValauePair, for example a Pet class. Then store these pets in a List<Pet>. I guess the value is the age, so you could provide a property DateTime Birthdate. The Age property would be calculated: int Age => DateTime.Today.Year - Birthdate.Year;. — Tim Schmelter
– Tim Schmelter, Commented Feb 21, 2018 at 12:34

Impostor · Accepted Answer · 2018-02-21 12:39:19Z

10

Here is a Linq appraoch with Where() and Sum()

int result = list.Where(x => x.Key == "Cat").Sum(x => x.Value);

or

int result = list.Sum(x => x.Key == "Cat" ? x.Value : 0);

edited Feb 21, 2018 at 12:39

answered Feb 21, 2018 at 12:32

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4 Comments

atc Over a year ago

if I pass "Rabbit", it will get only that number ( ie 4) ?

paparazzo Over a year ago

@aniltc You could try it

atc Over a year ago

new to LInq @Paparazzi

Jon Skeet Over a year ago

@aniltc: That doesn't stop you from trying it though, does it? Curiosity is important for learning things.

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