Why I'm getting:
Index and length must refer to a location within the string.
Parameter name: length
when I compile this code: http://pastebin.com/CW4EcCM8
some part of it:
public string findFileEnding(string file)
{
int index1 = file.IndexOf('.');
file = file.Substring(index1, file.Length);
return file;
}
Thanks;)
I am thinking there is a chance Path.GetExtension could be something OP might want instead.
notice that it returns extension with . like .exe
http://msdn.microsoft.com/en-us/library/system.io.path.getextension.aspx
The second argument to Substring, if present, is the desired length of the substring. So you're asking for a string the same length as file but starting at a position possibly different from 0. This would make the end of your substring to be past the end of file.
Assuming you want to get all of file starting at position index1, you can just leave out the second argument altogether:
file = file.Substring(index1);
To make this robust, you'll want to put in a few more checks:
file may be null.IndexOf may be -1. This would happen if file does not contain a dot.
IndexOf returning -1.That's not a compiler error, that's a runtime error.
Note the documentation for String.Substring(int, int):
Retrieves a substring from this instance. The substring starts at a specified character position [
startIndex] and has a specified length [length].
So the substring will have the specified length. Therefore, there must be enough characters starting at startIndex to return a substring of the specified length. Therefore, the following inequalities must be satisfied for String.Substring to succeed on an instance s of string:
startIndex >= 0
length >= 0
length > 0 implies startIndex + length <= s.Length
Note that if you just want a substring from index to the end of the string, you can say
s.Substring(index);
Here, the only constraint is
startIndex>= 0
startIndex < s.Length
You would want to do something like this:
public string FindFileEnding(string file)
{
if (string.IsNullOrEmpty(file))
{
// Either throw exception or handle the file here
throw new ArgumentNullException();
}
try
{
return file.Substring(file.LastIndexOf('.'));
}
catch (Exception ex)
{
// Handle the exception here if you want, or throw it to the calling method
throw ex;
}
}
string.IsNullOrEmpty(file) for you the first if-statement, as what you have is not valid unless you've defined a custom extension method. You should also check LastIndexOf's return value. Rethrowing that exception would not makes sense.
int index = file.LastIndexOf('.') but removed it as there was nothing stating how they wanted to handle errors or bad values