假设我有一个像这样的字符串数组：
string [] foos = {
"abc","def","ghi"
};
我想要一个包含每个字符串及其反向的新集合.所以结果应该是：
"abc","cba","fed","ghi","ihg"
我可以遍历数组,但这非常笨拙：
string Reverse (string str)
{
return new string (str.Reverse ().ToArray ());
}
List<string> results = new List<string> ();
foreach (string foo in foos) {
results.Add (foo);
results.Add (Reverse(str));
}
有没有办法在LINQ中执行此操作？就像是
var results = from foo in foos
select foo /* and also */ select Reverse(foo)
解决方法
var result = from foo in foos
from x in new string[] { foo,Reverse(foo) }
select x;
要么
var result = foos.SelectMany(foo => new string[] { foo,Reverse(foo) });
这将foos中的每个foo映射到一个由两个元素组成的数组：foo和Reverse(foo).然后它将所有这些双元素数组连接成一个大的可枚举数组.
{ { {
"abc",{
"abc","abc",},=> { =>
"def",}
"ghi",{
"ghi","ihg",}
} } }
如果输出的顺序不那么重要,您还可以使用Reverse方法将原始数组与映射原始数组中每个元素的结果连接起来：
var result = foos.Concat(from foo in foos select Reverse(foo));
要么
var result = foos.Concat(foos.Select(Reverse));
{ { {
"abc",=> "def",} }
concat
{
"cba",} }
