Re: typeof versus Type.GetType() - C# Discussion Boards

typeof versus Type.GetType()

26-Mar-05 8:16

Just FYI - the Visual Studio .NET's Add Reference's COM tab does the same thing as tlbimp.exe.

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Member 9625-Mar-05 5:50

Member 96

25-Mar-05 5:50

I ran a test (below) and typeof is many orders of magnitude faster than Type.GetType. I guess it's because of the searching that needs to be done.

My question is why does Microsoft show in all their examples of creating a datatable to use Type.GetType instead of typeof as the columns data type parameter?
[I.E. table.Columns.Add("name",Type.GetType("System.String")) instead of table.Columns.Add("name",typeof(System.String)) ]

I'm working on a project right now where I need to convert a hiearchical business object into a flat datatable for reporting purposes. There are a large number of columns to generate in code for many different objects so I'd prefer to go with what is fastest.

I'm fairly certain that typeof and Type.GetType are functionally identical in this case but I'm wondering why MS goes with the slower option in their samples?

Or is my testing wrong?

(Test for checking performance of typeof versus Type.GetType(""))

private void button1_Click(object sender, System.EventArgs e)<br />
		{<br />
			Cursor.Current=Cursors.WaitCursor;<br />
			<br />
			System.DateTime dtThen=DateTime.Now;<br />
			Type t;<br />
<br />
<br />
			for(int InfamousI=0;InfamousI<500000;InfamousI++)<br />
			{<br />
//Doing it this way takes .09 seconds on my computer<br />
<br />
				t=typeof(System.String);<br />
				t=typeof(System.DateTime);<br />
				t=typeof(System.Int32);<br />
				t=typeof(System.String);<br />
				t=typeof(System.DateTime);<br />
				t=typeof(System.Int32);<br />
				t=typeof(System.String);<br />
				t=typeof(System.DateTime);<br />
				t=typeof(System.Int32);<br />
				t=typeof(System.String);<br />
				t=typeof(System.DateTime);<br />
				t=typeof(System.Int32);<br />
<br />
<br />
//Doing it this way takes 8.9 seconds on my computer:<br />
<br />
//				t=Type.GetType("System.String");<br />
//				t=Type.GetType("System.DateTime");<br />
//				t=Type.GetType("System.Int32");<br />
//				t=Type.GetType("System.String");<br />
//				t=Type.GetType("System.DateTime");<br />
//				t=Type.GetType("System.Int32");<br />
//				t=Type.GetType("System.String");<br />
//				t=Type.GetType("System.DateTime");<br />
//				t=Type.GetType("System.Int32");<br />
//				t=Type.GetType("System.String");<br />
//				t=Type.GetType("System.DateTime");<br />
//				t=Type.GetType("System.Int32");<br />
//				<br />
			}<br />
			MessageBox.Show("Elapsed: " + (System.DateTime.Now-dtThen).ToString());<br />
		}

Heath Stewart25-Mar-05 11:34

25-Mar-05 11:34

John,

Microsoft and other ISVs use the CodeDom to output text so that any language that provides a CodeDom provider (like C# and VB.NET) can create source code for a particular component. The component uses the CodeDom to generically create source code using the CodeDom provider.

Why Microsoft does not use the CodeTypeOfExpression class I cannot say for certain (I'm not on that team, though I'm in the same division) but I suspect it is because not all language may support a typeof expression. I can try to find out and let you know.

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Member 9625-Mar-05 13:59

Member 96

25-Mar-05 13:59

I guess I should just take the examples with a grain of salt like I used to in my c++ days.

After many many many years of programming in C++ I was able to interpret the microsoft samples but do it the most efficient way myself. With c# I only have a couple of years under my belt and so I'm prone to deferring to the examples more.

I guess the danger of the samples is that they can perpetuate something out to the general public to the point where it's not questioned. When I looked up this earlier, I found hundreds of non-ms websites and newsgroup postings referring to this process and they all used the MS Type.GetType variant in their c# examples.

I know it's probably trivial, but someone at MS should go through all those samples as time permits and consider if they are setting a good example. Newbies like me are quite dependant on them and they seem to flow out to other developer sites as well. There is still a place I believe for efficiency and good old optimization.

Heath Stewart25-Mar-05 14:31

25-Mar-05 14:31

I would recommend that you pay too much attention to samples. Study the documentation and if you really want to be elite use ildasm.exe (or .NET Reflector, but then you use geek points if you don't use the IL view Smile | :)

) to view the implementation. If you're having problems understanding the documentation (hey...it happens!) the samples can sometimes help.

I actually have been reporting several problems in samples (like GetProcAddress(TEXT("SomeFunction"));, since GetProcAddress only accepts LPCSTR, which is ANSI and the TEXT macro causes strings to be treated as Unicode when _UNICODE is defined) and I recommend you do the same. Most topics have a link at the bottom to send feedback. All of the .NET Framework SDK topics should.

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Tom Larsen25-Mar-05 12:21

Tom Larsen

25-Mar-05 12:21

I can't say why their examples use Type.GetType but I could have guessed that typeof is simply faster than Type.GetType.

Check this out...
System.Type t = typeof(System.String);
Seems to generate this il:

<br />
ldtoken    [mscorlib]System.String<br />
call       class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)<br />

While...

<br />
System.Type t = System.Type.GetType("System.String");<br />

Seems to generate this il:

<br />
ldstr      "System.String"<br />
call       class [mscorlib]System.Type [mscorlib]System.Type::GetType(string)<br />

Without going farther, I suspect that GetTypeFromHandle is way more speedy than the generic GetType. One has the handle reference readily available for inspection while the other has to go looking for it.

Heath Stewart25-Mar-05 14:28

25-Mar-05 14:28

The latter also has a change of breaking at runtime if the Type is not defined in the current assembly. The former (typeof) is checked at compile time and you can be sure that the type will be found (so long as the entire assembly isn't missing or the version redirected to where the Type isn't defined) at run-time.

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Member 9625-Mar-05 16:39

Member 96

25-Mar-05 16:39

Heath Stewart wrote:
latter also has a change of breaking at runtime if the Type is not defined in the current assembly.

Good point! Even more reason to use typeof. It would be pretty easy to mistype the class name with Type.GetType() and not catch it.

Generate Word Document in C#

Shardool25-Mar-05 14:39

Shardool

25-Mar-05 14:39

Thats about right .... with type of the type is kindda known .. .where as in the other one it is looked up from a string literal .....

- The Outlander -

Michele@MERC25-Mar-05 5:24

25-Mar-05 5:24

Hi ~

I am generateing a Word Document in C# and need to put page numbers and information in the footer.
However, when I add information to the Range.Text the page numbers do not display correctly.

This is what I get -

Page 1 of 1 ( Same on all the pages )
*******************
* Somthing here *
*******************

This is what I need -

Page 1 of 47
*******************
* Something Here *
*******************

This is the code I have -

_WordDoc.Sections.First.Footer.Item(Word.WdHenderFooterIndex.wdHeaderFooterPrimary).Range.Text = "Page X of Y";

_WordDoc.Sections.First.Footer.Item(Word.WdHenderFooterIndex.wdHeaderFooterPrimary).Range.InsertAutoText();

_WordDoc.Sections.First.Footer.Item(Word.WdHenderFooterIndex.wdHeaderFooterPrimary).Range.Text += "\n" + String1 + String2 + String3;

Confused | :confused:

Michele
Mercer Engineering Research Center
mstusak@merc.mercer.edu

Heath Stewart25-Mar-05 12:16

25-Mar-05 12:16

When doesn't it display correctly? When you open the document in Word or when you print it? In the latter case, make sure to set Options.UpdateFieldsAtPrint to true.

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Michele@MERC29-Mar-05 4:13

29-Mar-05 4:13

Thank you for your help - it does not display correctly when I open the document in Word.

- Michele -

Michele
Mercer Engineering Research Center
mstusak@merc.mercer.edu

Heath Stewart29-Mar-05 5:29

29-Mar-05 5:29

Just to make sure that the auto-text conversion / recognition is working correctly, when you open it in word find that portion of the document footoer and select either the "X" or "Y" (what they originally were). These should appear as gray blocks that are fields. Make sure that they are fields. If not, you'll have to actually insert the auto-text entries rather than getting Word to recognize that they are. Let me know if they are fields and I can post some example code if not.

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Software Design Engineer
Developer Division Sustained Engineering
Microsoft

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Michele@MERC29-Mar-05 6:29

29-Mar-05 6:29

No the auto-text conversion/recognition does not see the "X" or "Y" as fields if I place any other text in the footer. However, if I do not place any text and only use the auto text the conversion/recognition does place fields in the footer.

Michele
Mercer Engineering Research Center
mstusak@merc.mercer.edu

Heath Stewart29-Mar-05 8:35

29-Mar-05 8:35

Then you'll have to add it as an AutoText entry itself. Please note this is sample code and is not checked, but should give you the right idea.

_WordDoc.AttachedTemplate.AutoTextEntries("Page X of Y").Insert(
  _WordDoc.Sections.First.Footer.Item(WdHeaderFooterIndex.wdHeaderFooterPrimary).Range,
  true);

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Software Design Engineer
Developer Division Sustained Engineering
Microsoft

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Michele@MERC30-Mar-05 3:30

30-Mar-05 3:30

I understand what you are saying, however I can not access the Templates. AttachedTemplate is not supported in C#. The closest I have come is -

_WordDoc.Application.Templates.Item(ref Index).AutoTextEntries.Add("Page X of Y", _WordDoc.Sections.First.Footer.Item(WdHeaderFooterIndex.wdHeaderFooterPrimary).Range)

- but this is not working. Do you know of any other way to access the templates in C#.

Michele
Mercer Engineering Research Center
mstusak@merc.mercer.edu

Heath Stewart30-Mar-05 5:17

printing results from printer

30-Mar-05 5:17

The Document class does define the AttachedTemplate property but you must cast it to the proper type, which is the Template class. Since this is an interop assembly, members are not always strongly typed as they are in .NET because some times objects simply return IDispatch in a retval parameter. As I mentioned in my previous post, the code wasn't verified but it is close:

Template tmpl = _WordDoc.ActiveDocument.AttachedTemplate as Template;
if (tmpl != null)
{
  // ...
}

Looking through the assembly - which you can do using ildasm.exe that ships with the .NET Framework SDK, or .NET Reflector[^], you can often see what must be done using COM interop assemblies. For documentation, use the automation or object model documentation for a product since an interop assembly marshals calls to the COM server (the automation object) using the same type definitions from a typelib as, say, VB6 would do.

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Member 178719025-Mar-05 4:45

Member 1787190

25-Mar-05 4:45

hi folks
i want to print my statistical results directly from the printer without saving in the file or so
how can i do that
thaxs

Re: printing results from printer

Heath Stewart25-Mar-05 11:11