how to remove a item from System.Collections.Generic.List in a loo

[=?Utf-8?B?emhhbmdscg==?=]

Hi,

Following code does not work. (it will crash.)-- I think the reason is that
I cannot modify list (call remove) in foreach. But I don't know what I can
do.

-----------------------------------------------------------------------
List<stringarstr = new List<string>();
//init data
for (int i = 0; i < 30; ++i)
{
arstr.Add(i.ToString());
}

//go through items one by one
//and remove item start with 1 e.g. 1, 10,11...,100...
foreach (string str in arstr)
{
if (str.Length 0 && str[0] == '1')
{
arstr.Remove(str);
}
}

//print the result
foreach (string str in arstr)
{
Console.WriteLine(str);
}

Best Regards,
Michael zhang

[Alex Meleta]

Hi zhanglr,

Make a new list of removing objects and remove them after the loop (you cannot
modify the list of foreach during its execution).
But, it may be better to make the list of passed objects instead of deleted.

Kind Regards, Alex Meleta
[TechBlog] http://devkids.blogspot.com

zHi,
z>
zFollowing code does not work. (it will crash.)-- I think the reason
zis that I cannot modify list (call remove) in foreach. But I don't
zknow what I can do.
z>
z---------------------------------------------------------------------
z--
zList<stringarstr = new List<string>();
z//init data
zfor (int i = 0; i < 30; ++i)
z{
zarstr.Add(i.ToString());
z}
z//go through items one by one
z//and remove item start with 1 e.g. 1, 10,11...,100...
zforeach (string str in arstr)
z{
zif (str.Length 0 && str[0] == '1')
z{
zarstr.Remove(str);
z}
z}
z//print the result
zforeach (string str in arstr)
z{
zConsole.WriteLine(str);
z}
zBest Regards,
zMichael zhang

[=?Utf-8?B?emhhbmdscg==?=]

Hi,

First of all, thank you for your reply.

I just wonder whether there is any better way. E.g. in C++ we are able to
call std::remove_if or list::erase (the return value is iterator so I am able
to continue.) I think maybe MS has provided the samilar functions. I just
haven't found it yet.

At the end, thanks for your reply again.

Best Regards
Michael zhang

"Alex Meleta" wrote:

Hi zhanglr,

Make a new list of removing objects and remove them after the loop (you cannot
modify the list of foreach during its execution).
But, it may be better to make the list of passed objects instead of deleted.

Kind Regards, Alex Meleta
[TechBlog] http://devkids.blogspot.com

zHi,
z>
zFollowing code does not work. (it will crash.)-- I think the reason
zis that I cannot modify list (call remove) in foreach. But I don't
zknow what I can do.
z>
z---------------------------------------------------------------------
z--
zList<stringarstr = new List<string>();
z//init data
zfor (int i = 0; i < 30; ++i)
z{
zarstr.Add(i.ToString());
z}
z//go through items one by one
z//and remove item start with 1 e.g. 1, 10,11...,100...
zforeach (string str in arstr)
z{
zif (str.Length 0 && str[0] == '1')
z{
zarstr.Remove(str);
z}
z}
z//print the result
zforeach (string str in arstr)
z{
zConsole.WriteLine(str);
z}
zBest Regards,
zMichael zhang

[Alex Meleta]

Hi zhanglr,

Because you will have two arrays: one as a source (as immutable) and second
is filtered. Safe way.

And yes, MS provides similar functions: you can also use e.g. list.RemoveAll(delegate(int
value) { return <some_case_to_return_bool>; }) to clear particular values
(see also other .Remove<somefunctions of list)

Kind Regards, Alex Meleta
[TechBlog] http://devkids.blogspot.com

zHi,
z>
zFirst of all, thank you for your reply.
z>
zI just wonder whether there is any better way. E.g. in C++ we are
zable to call std::remove_if or list::erase (the return value is
ziterator so I am able to continue.) I think maybe MS has provided the
zsamilar functions. I just haven't found it yet.
z>
zAt the end, thanks for your reply again.
z>
zBest Regards
zMichael zhang
z"Alex Meleta" wrote:
z>

>Hi zhanglr,

Make a new list of removing objects and remove them after the loop
(you cannot modify the list of foreach during its execution). But, it
may be better to make the list of passed objects instead of deleted.

Kind Regards, Alex Meleta
[TechBlog] http://devkids.blogspot.com
zHi,
z>
zFollowing code does not work. (it will crash.)-- I think the
reason
zis that I cannot modify list (call remove) in foreach. But I don't
zknow what I can do.
z>
z>
---------------------------------------------------------------------
z--
zList<stringarstr = new List<string>();
z//init data
zfor (int i = 0; i < 30; ++i)
z{
zarstr.Add(i.ToString());
z}
z//go through items one by one
z//and remove item start with 1 e.g. 1, 10,11...,100...
zforeach (string str in arstr)
z{
zif (str.Length 0 && str[0] == '1')
z{
zarstr.Remove(str);
z}
z}
z//print the result
zforeach (string str in arstr)
z{
zConsole.WriteLine(str);
z}
zBest Regards,
zMichael zhang

[=?Utf-8?B?emhhbmdscg==?=]

Hi,

Thank you so much.

Best Regards,
Michael zhang

"Alex Meleta" wrote:

Hi zhanglr,

Because you will have two arrays: one as a source (as immutable) and second
is filtered. Safe way.

And yes, MS provides similar functions: you can also use e.g. list.RemoveAll(delegate(int
value) { return <some_case_to_return_bool>; }) to clear particular values
(see also other .Remove<somefunctions of list)

Kind Regards, Alex Meleta
[TechBlog] http://devkids.blogspot.com

zHi,
z>
zFirst of all, thank you for your reply.
z>
zI just wonder whether there is any better way. E.g. in C++ we are
zable to call std::remove_if or list::erase (the return value is
ziterator so I am able to continue.) I think maybe MS has provided the
zsamilar functions. I just haven't found it yet.
z>
zAt the end, thanks for your reply again.
z>
zBest Regards
zMichael zhang
z"Alex Meleta" wrote:
z>

Hi zhanglr,

Make a new list of removing objects and remove them after the loop
(you cannot modify the list of foreach during its execution). But, it
may be better to make the list of passed objects instead of deleted.

Kind Regards, Alex Meleta
[TechBlog] http://devkids.blogspot.com
zHi,
z>
zFollowing code does not work. (it will crash.)-- I think the
reason
zis that I cannot modify list (call remove) in foreach. But I don't
zknow what I can do.
z>
z>
---------------------------------------------------------------------
z--
zList<stringarstr = new List<string>();
z//init data
zfor (int i = 0; i < 30; ++i)
z{
zarstr.Add(i.ToString());
z}
z//go through items one by one
z//and remove item start with 1 e.g. 1, 10,11...,100...
zforeach (string str in arstr)
z{
zif (str.Length 0 && str[0] == '1')
z{
zarstr.Remove(str);
z}
z}
z//print the result
zforeach (string str in arstr)
z{
zConsole.WriteLine(str);
z}
zBest Regards,
zMichael zhang