I try to Reverse my string but I get to following error
string str = word.Reverse();
error:
cannot convert from 'System.Collections.Generic.IEnumerable' to
'string'
anyone know what should I need to do ?
You should build a new string.
string str = new string(word.Reverse().ToArray());
Calling ToArray() on an IEnumerable<T> will convert it to T[].
string has a constructor which get array of character and constructs a string.
You should join characters together to make new string.
string str = string.Join(string.Empty, word.Reverse());
Related
I'm a newbie to C#. When I run this program, I'm getting a compile type error
CS0266 cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'string'
Is my syntax wrong?
class Program
{
static void Main(string[] args)
{
string s = "Hello";
s = s.Concat("World");
}
}
You getting this error because the Concat function you have called is from LINQ. See here Enumerable.Concat. As a string is basically an enumeration of characters.
You have a variety of options to concatenate strings.
Just the + operator
string s = "Hello";
s = s + "World";
Or shorthand:
string s = "Hello";
s += "World";
static Concat function from string
string s = "Hello";
s = string.Concat(s, "World");
String Interpolation
string s = "Hello";
s = $"{s}World";
Concat is a Linq extension method that allows to concat two IEnumerable<char>, so you need to write that to convert the resulting array in a string:
s = new string(s.Concat("World").ToArray());
Here the s value as an array of chars, that is an IEnumerable<char>, is executing the Concat method on it using the same thing for the string provided as parameter (an array of chars).
But you may prefer writing, with a space, this standard string concatenation:
s += " World";
That is the same of:
s = s + " World";
Enumerable.Concat(IEnumerable, IEnumerable) Method
No need to go for complex and advanced techniques being a newbie.
In this scenario, concatenation can be done in simple way:
class Program
{
static void Main(string[] args)
{
string s = "Hello";
s = s + "World";
}
}
I would like to do some kind of console framework and for that I need command and arguments for the command. Here is part of my code:
string str = "I do not know how to fix this problem";
List<string> substringList = str.Split().ToList();
List<string> allArgsExcept1st = str[1..^0].ToList();
The input is type string.
The third line throws an error:
Cannot implicitly convert type 'System.Collections.Generic.List<char>' to 'System.Collections.Generic.List<string>'.
I am new to C# so I don't know what to think about this error and how to possibly fix it.
Thank you.
Based on your latest edit:
string str = "I do not know how to fix this problem";
List<string> substringList = str.Split().ToList();
List<string> allArgsExcept1st = str[1..^0].ToList();
The problem you have is here:
str[1..^0].ToList()
When you are using the range/slice function ([1..^0]) on your string you are, in return, getting a string. So calling ToList() on that string will give you a List<char> (since a string is also a IEnumerable<char>) but you are assigning it to a List<string>.
Its unclear what you are ultimately trying to do here, but to fix your problem you just need to change your last line to:
List<char> allArgsExcept1st = str[1..^0].ToList();
I want to do the following but I get this
Error: an Implicit conversion from type Char[] to string is not
possible.
string Pattern2 = (Convert.ToDateTime(currMail.CreationTime).ToString(" dd-MMM-yyyy HH-mm")).ToArray();
Does anybody have any idea as on how to deal with this?
Remove .ToArray():
string Pattern2 = Convert.ToDateTime(currMail.CreationTime).ToString("dd-MMM-yyyy HH-mm");
As the other answers point out, your call to ToArray is not just unnecessary, it is in this case actively harmful. You already have a string in hand, you need a string, so don't convert the string to an array of char; just use the string.
However, for your future reference it is possible to convert an array of char to a string, just not via an implicit or explicit conversion. The syntax for that is:
char[] characters = whatever;
string str = new String(characters);
Finally, the documentation is here:
http://msdn.microsoft.com/en-us/library/vstudio/s1wwdcbf.aspx
Beginners should familiarize themselves with this documentation; there's a lot of good stuff in there.
Looks like you don't need to use .ToArray() method at all. You already using .ToString() method for assigning to your Pattern2 variable.
Just use as;
string Pattern2 = Convert.ToDateTime(currMail.CreationTime).ToString("dd-MMM-yyyy HH-mm");
string Pattern2 = Convert.ToDateTime(currMail.CreationTime).ToString(" dd-MMM-yyyy HH-mm");
You assign a char[] to a string, which requires conversion from the char[] to a string. As the error says, this is not done implicitly, i.e. behind the scenes. This is done to prevent silly mistakes.
You are expected to make an explicit conversion (create a string from the array and then assign it).
In your case you have a string and convert it to an array before assigning it to Pattern2. Just don't convert the string to an array.
string Pattern2 = (Convert.ToDateTime(currMail.CreationTime).ToString(" dd-MMM-yyyy HH-mm"));
I am trying to read a string into an array and I get the error "Cannot implecitly convert type 'string' to 'string[]'.
The error occurs here:
string[] sepText = result.Tables[0].Rows[0].Field<string>("WebHTML").UrlDecode();
My full if else statement is below:
if (!string.IsNullOrEmpty(result.Tables[0].Rows[0].Field<string>("WebHTML")))
{
string[] sepText = result.Tables[0].Rows[0].Field<string>("WebHTML").UrlDecode();
NewsContent.Text = sepText[1];
if (!string.IsNullOrEmpty(sepText[0]))
Image1.ImageUrl = sepText[0];
else
Image1.Visible = false;
NewsTitle.Text = String.Format("{3}", Extensions.GetServerName(true), result.Tables[0].Rows[0].Field<int>("News_Item_ID"), result.Tables[0].Rows[0].Field<string>("Title").UrlFormat(), result.Tables[0].Rows[0].Field<string>("Title"));
Hyperlink1.NavigateUrl = String.Format("{0}/news/{1}/{2}.aspx", Extensions.GetServerName(true), result.Tables[0].Rows[0].Field<int>("News_Item_ID"), result.Tables[0].Rows[0].Field<string>("Title").UrlFormat());
}
else
{
Hyperlink1.Visible = false;
Image1.Visible = false;
}
Thank you for your help!
EDIT Code for URL Decode:
public static string UrlDecode(this string str)
{
return System.Web.HttpUtility.UrlDecode(str);
}
result.Tables[0].Rows[0].Field<string>("WebHTML") is going to give you the value of the WebHTML field in the first row in the first table which is a single string rather than a string[].
You may want to show your code for UrlDecode() since it looks like a custom implementation rather than one of the built-in framework versions.
You also declare the UrlDecode method to take a string as a parameter and return a string. Remember, a string is not the same thing as a string array.
It seems that you are trying to put:
result.Tables[0].Rows[0].Field<string>("WebHTML").UrlDecode();
which returns a string, into an array of strings.
Simply delare your sepText variable as a string rather than a string array and you should be good to go, e.g.:
string sepText = result.Tables[0].Rows[0].Field<string>("WebHTML").UrlDecode();
Later in your code you will clearly need to read the contents of the string like this:
Image1.ImageUrl =sepText;
Assuming the UrlDecode you are using is the one from here then the result is a string and not a string[] !
UrlDecode returns a string and you are assigning it to an array.
If you want the parts you will have to use the string to create an Url object.
Url url = new Url(result.Tables[0].Rows[0].Field<string>("WebHTML"));
and then get the parts.
See: Get url parts without host
I don't think URLDecode works the way you think it works. All URLDecode does is remove URL encoding from a string. It does not return an array of strings - only the decoded value of the string you gave it.
http://msdn.microsoft.com/en-us/library/system.web.httputility.urldecode.aspx
Example: Your web browser replaces a space with %20. This changes the %20 back to a space.
That's because the result of this line is "string" and you're trying to assign it to an array since UrlDecode do not produce an array. What you probably wanted is to use a method split() to create an array of separators?
I"m developing a simple application that have a line like this:
string[] values = ReadAll(inputFile);
As inputFile is a string, but how I can do this without conflicts(Cannot implicitly convert type 'string' in 'string[]')?
Assuming your ReadAll method has a signature like this
string ReadAll(string inputFile);
then the problem is not with inputFile but with the return value of the method which cannot be assigned to a string[].
Are you maybe looking for File.ReadAllLines?
string[] values = File.ReadAllLines(inputFile);
Or do you want to split a string by some delimeter?
string[] values = ReadAll(inputFile).Split('\n');
Based on the exception message you gave us, ReadAll(inputFile) returns a string, and you assign it to a string[], so that's why it doesn't work.
This would work:
string input = ReadAll(inputFile);
After this do you want to split the strings in some way? We'd need more details to help you further.