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I’ve been working on the Microsoft Imagine Cup 2009 competition for the Game Design with one of my class mate. I looked at the sample codes to identify the location for the intersection between a ray and the vertex of a mesh. I recognized that the sample code that checks the distance between the ray and the intersection has a weird question mark that I have never seen in any other languages (i.e. float? intersection). The question mark is usually placed right after the primitive data types such as float, int, double, etc. I looked over the web and I found this:
public System.Data.DataSet GetRecords(int? foreignKey)
From the example above, it is quite easy to notice the inclusion of the ? character after the data type of the parameter. This function could now be called with an integer or NULL for the parameter. A parameter has to be specified, however, because C# does not allow default parameters for some stupid unknown reason. You guessed it, this becomes really useful when you are executing statements on a database that contains fields that are null-able but defined as an ordinal type. (Ordinal types are int, bool, double, float etc. etc.)
Note that question mark is commonly used in many other languages to declare a conditional if.. else.. statement:
([condition])? [value if true] : [value if false]
The Fundamental Differences
The HTML specifications technically define the difference between “GET” and “POST” so that former means that form data is to be encoded (by a browser) into a URL while the latter means that the form data is to appear within a message body. The “GET” method should be used when the form processing is “idempotent”, and in those cases only. As a simplification, we might say that “GET” is basically for just getting (retrieving) data whereas “POST” may involve anything, like storing or updating data, or ordering a product, or sending E-mail.
Differences in Form Submission
- If the
methodis"get"- -, the user agent takes the value ofaction, appends a?to it, then appends the form data set, encoded using theapplication/x-www-form-urlencodedcontent type. The user agent then traverses the link to this URI. In this scenario, form data are restricted to ASCII codes. - If the
methodis"post"–, the user agent conducts an HTTPposttransaction using the value of theactionattribute and a message created according to the content type specified by theenctypeattribute.
Thus, for METHOD=”GET” the form data is encoded into a URL (or, speaking more generally, into a URI). This means that an equivalent to a form submission can be achieved by following a normal link referring to a suitable URL; On a typical browser, the user sees the URL of a document somewhere (e.g. on Location line), and if he is viewing the results of a query sent using METHOD=”GET”, he will see what the actual query was (i.e. the part of the URL that follows the ? sign). The user could then bookmark it or cut&paste it for later use (e.g. to be E-mailed or put into one’s own HTML document after some editing).
8Come near to God and he will come near to you. Wash your hands, you sinners, and purify your hearts, you double-minded. 9Grieve, mourn and wail. Change your laughter to mourning and your joy to gloom. 10Humble yourselves before the Lord, and he will lift you up.
I feel that sometimes it’s difficult to find all-in-one answers to our basic questions in the job interview. I appreciate the University of Chicago for compiling the answers into one document. I hope that this would also be helpful for other international students.
22 Cast your cares on the LORD
and he will sustain you;
he will never let the righteous fall.















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