I just wondered why this ForEach doesn't work and leaves the values with trailing whitespace.
string days = "Monday, Tuesday, Wednesday, Thursday, Friday";
string[] m_days = days.Split(',');
m_days.ToList().ForEach(d => { d = d.Trim(); } );
I know there are other ways of doing this so i don't need and answer there.
Because you are not reassigning the trimmed strings.
var list = m_days.Split(',').Select(s => s.Trim()).ToList();
Why
ForEachdoesn't work or if I am using theForEachincorrectly?
ForEach is not Linq, it's a method of List<T>. What you are doing is basically this:
foreach(string day in m_days)
{
day.Trim(); // you are throwing away the new string returned by String.Trim
}
Instead of using LINQ you could also use a for-loop instead:
for(int i = 0; i < m_days.Length; i++)
{
m_days[i] = m_days[i].Trim();
}
ForEach for this task.
ForEach is not Linq, it's a method of List<T>. Edited my answer.You need to assign the output of your ForEach to a new variable, like so:
var trimmedResult = m_days.Select(d => d.Trim()).ToList();
string.Trim returns a new string instance. So you have to somehow use that new instance.
You are not doing that in your code.
Furthermore, it is not possible with ForEach. At first glance, the following could work:
m_days.ToList().ForEach(d => { d = d.Trim(); });
But that isn't going to help you either, because d is not passed by reference, so you are only changing the local parameter that has been passed into your delegate and not the instance stored in the list.
You most likely want this:
var result = days.Split(',').Select(x => x.Trim()).ToList();
An alternate way without LINQ would look like this:
var split = days.Split(',');
for(int i = 0; i < split.Length; ++i)
split[i] = split[i].Trim();
Because String.Trim() do not modify original string. When you call ForEach(d => d.Trim()) you create new trimmed string in memory for each item of list, but that string is not assigned anywhere. Thats what you are doing:
foreach(string d in list)
{
d.Trim();
}
What you need is
m_days = days.Split(',').Select(d => d.Trim()).ToArray();
