For clarity, if I’m using a language that implements IEE 754 floats and I declare: float f0 = 0.f; float f1 = 1.f; …and then print them back out, I’ll get 0.0000 and 1.0000 – exactly. But IEEE 754 isn’t capable of representing all the numbers along the real line. Close to zero, the ‘gaps’ … Read more
I saw the “new type” BOOL (YES, NO). I read that this type is almost like a char. For testing I did : NSLog(@”Size of BOOL %d”, sizeof(BOOL)); NSLog(@”Size of bool %d”, sizeof(bool)); Good to see that both logs display “1” (sometimes in C++ bool is an int and its sizeof is 4) So I … Read more
I read through the Wikipedia article Existential types. I gathered that they’re called existential types because of the existential operator (∃). I’m not sure what the point of it is, though. What’s the difference between T = ∃X { X a; int f(X); } and T = ∀x { X a; int f(X); } ? … Read more
In multiple courses, books, and jobs, I have seen text fields defined as VARCHAR(255) as kind of the default for “shortish” text. Is there any good reason that a length of 255 is chosen so often, other than being a nice round number? Is it a holdout from some time in the past when there … Read more
Basically I want to do this: obj = ‘str’ type ( obj ) == string I tried: type ( obj ) == type ( string ) and it didn’t work. Also, what about the other types? For example, I couldn’t replicate NoneType. 14 Answers 14
I’m using R and have loaded data into a dataframe using read.csv(). How do I determine the data type of each column in the data frame? 11 Answers 11
I am trying to convert my string formatted value to date type with format dd/MM/yyyy. this.Text=”22/11/2009″; DateTime date = DateTime.Parse(this.Text); What is the problem ? It has a second override which asks for IFormatProvider. What is this? Do I need to pass this also? If Yes how to use it for this case? Edit What … Read more
I’m confused on what an immutable type is. I know the float object is considered to be immutable, with this type of example from my book: class RoundFloat(float): def __new__(cls, val): return float.__new__(cls, round(val, 2)) Is this considered to be immutable because of the class structure / hierarchy?, meaning float is at the top of … Read more
Today I was positively surprised by the fact that while reading data from a data file (for example) pandas is able to recognize types of values: df = pandas.read_csv(‘test.dat’, delimiter=r”\s+”, names=[‘col1′,’col2′,’col3’]) For example it can be checked in this way: for i, r in df.iterrows(): print type(r[‘col1’]), type(r[‘col2’]), type(r[‘col3’]) In particular integer, floats and strings … Read more
So, normally ArrayList.toArray() would return a type of Object[]….but supposed it’s an Arraylist of object Custom, how do I make toArray() to return a type of Custom[] rather than Object[]? 6 Answers 6
