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c#lambda
John Tan
John Tan

Reputation: 1385

Using lambda expression to change values inside a list

I have a variable defined as:

List<List<A>> mylist;

where

public class A
{
    int b;
    int c;
}

I was wondering if there is a lambda expression that can do the following:

for(int i = 0; i < mylist.Count; ++i)
{
    for(int j = 0; j < mylist[i].Count; ++j)
    {
        if(mylist[i][j].b < 10) mylist[i][j].b = 0;
        else mylist[i][j].b = 1;
    }
}

Upvotes: 0

Views: 3201

Answers (2)

crthompson
crthompson

Reputation: 15865

Your for loop can be converted to this:

List<List<A>> mylist = new List<List<A>>();

foreach (var t1 in mylist.SelectMany(t => t))
{
   t1.b = t1.b < 10 ? 0 : 1;
}

Upvotes: 4

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 476534

Although there is some discussion about the usability of the List<T>.ForEach statement, this can perform this task:

mylist.ForEach(x => x.Foreach(y => y.b = (y.b < 10) ? 0 : 1));

Or unroll it in a foreach loop:

foreach(List<A> la in mylist) {
    foreach(A a in la) {
        a.b = (a.b < 10) ? 0 : 1;
    }
}

The (condition) ? val_true : val_false is the ternary operator.

Upvotes: 1

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