primitive

问题 First off: I had another question Creating a 2D polygon in XNA but I answered it myself after a day of frustrating research and testing. There you can find the code I have right now. So here is my next question, as I can't find anything about it. How do I animate a VertexPositionColor[] . 回答1: To animate a VertexPositionColor[], all you really need to do is modify the elements of the array appropriately and then use the new values in your DrawUserPrimitives() call. For example, in the Update

问题 Please, could you help me to understand why compilation of first call of testVargArgsAutoboxingPriority fails? In case of second call compiler is able to select proper method by preferring primitive (first parameter) to Object but after varargs parameter addition compiler is not able to make the selection any more. Fail message is \jdk1.6.0_45\bin\javac.exe ocjp6/AutoBoxingOldStyleVarargsPriority.java ocjp6\AutoBoxingOldStyleVarargsPriority.java:7: reference to testVargArgsAutoboxingPriority

问题 im working in a simple graphical library in C with turbo C++ because im developing a very primitive version of a paint style program, everyting works well but i can´t get the flood fill algorithm to work. Im using the 4 way flood fill algorithm, first i tried with the recursive version but it only work with small areas, filling large areas make it crash; reading i found that implement an explicit stack version of it solve the problem but i don´t really see it. I have developed a stack like

问题 Why the following works float f = 10l // OK 32 bits to 64 ? float is only 32 bits and long 64 bits so there is NO room for float in the long and this one doesn't long l = 10f //compile error Could someone explain to me how kind of casting works? 回答1: The conversion from long to float is specifically allowed for assignment by the JLS, Section 5.1.2: 19 specific conversions on primitive types are called the widening primitive conversions: byte to short, int, long, float, or double short to int,

问题 What is the difference between objective-c C primitive numbers? I know what they are and how to use them (somewhat), but I'm not sure what the capabilities and uses of each one is. Could anyone clear up which ones are best for some scenarios and not others? int float double long short What can I store with each one? I know that some can store more precise numbers and some can only store whole numbers. Say for example I wanted to store a latitude (possibly retrieved from a CLLocation object),

问题 I'm attempting to define an extremely simple utility method that will save me from having to use a calculator to define RGB values as percentages. When I look into Apple's sample code called "QuartzCache", in the DrawView.m file, line 96, I see this: float whiteColor[4] = {1, 1, 1, 1}; However, when I attempt to created a method like the following, the compiler hates me. A half-hour of intensive Googling has not produced any help. +(float[])percentagesRGBArray:(float[])rgbArray{ float red =

问题 Is it possible to copy a primitive like String so it can be extended only in the current function? var foo = function() { var String = // somehow clone String (the primitive function) String.prototype.first = function() { return this.charAt(0) }; return 'abc'.first(); } foo(); // returns 'a' 'abc'.first(); // returns TypeError "abc".first is not a function The solution must either copy the primitive which doesn't seem possible, or destroy the new method after the function is complete... 回答1:

问题 By default, Java does Binary Numeric Promotion for primitives, but does not do the same thing for objects. Here's a quick test to demonstrate: public static void main(String... args) { if(100 == 100L) System.out.println("first trial happened"); if(Integer.valueOf(100).equals(Long.valueOf(100))) { System.out.println("second trial was true"); } else { System.out.println("second trial was false"); } if(100D == 100L) System.out.println("third trial, fun with doubles"); } Output: first trial

问题 In the comments here -- https://stackoverflow.com/a/9393138/8047 -- I discovered that BOOL has some unexpected behavior when setting its value from an int value. Mostly, if the value is set to 0x1000 it gets evaluated as FALSE (surprisingly). NSLog(@"All zero? %d %d", (BOOL)0, (bool)0); NSLog(@"All one? %d %d %d", (BOOL)4095, (BOOL)4096, (BOOL)4097); // 4096=0x1000 or 8-bits NSLog(@"All one? %d %d %d", (bool)4095, (bool)4096, (bool)4097); Produces: All zero? 0 0 All one? -1 0 1 All one? 1 1 1

问题 What's the largest value an NSNumber can store? // ok NSNumber *value = @(1 << 31); // gives compiler error, so max NSNumber is 32-bit uint? NSNumber *value = @(1 << 32); 回答1: NSNumber is actually a class cluster, meaning that when you create an instance you may be getting any of a variety of concrete subclasses, each capable of storing a different kind of numeric type. The actual types available, and their sizes, may be machine-dependent. Looking at the NSNumber documentation shows you the