default

问题 Converting a C++ lib to ANSI C and it seems like though ANSI C doesn't support default values for function variables or am I mistaken? What I want is something like int funcName(int foo, bar* = NULL); Also, is function overloading possible in ANSI C? Would need const char* foo_property(foo_t* /* this */, int /* property_number*/); const char* foo_property(foo_t* /* this */, const char* /* key */, int /* iter */); Could of course just name them differently but being used to C++ I kinda used to

问题 What is default storage class of a global variable? While searching on web I found, some sites say it is static . But, static means internal linkage and the variable can not be available outside the file scope i.e it should not be available to other object files. But, they still can be accessed to other files using declarations like extern int i . And, if I explicitly mention static to global variable then it is not available outside the file scope. Then, what is correct default storage class

问题 I have a plot with two histograms. However, it is difficult to tell which histogram on the plot is coming from the first set of data and which graphs the second set of data. There is a different colored line for each histogram: one is blue, and the other is green. Does the default MATLAB 'ColorOrder' vary between devices? If not - what is the order? 回答1: Good question! There is a default colour order for MATLAB. Take note that versions before R2014b, the default colour order for MATLAB uses

问题 In traditional object-oriented languages (e.g. Java), it is possible to "extend" the functionality of a method in an inherited class by calling the original method from the super class in the overridden version, for example: class A { public void method() { System.out.println("I am doing some serious stuff!"); } } class B extends A { @Override public void method() { super.method(); // here we call the original version System.out.println("And I'm doing something more!"); } } As you can see, in

问题 Why am I getting an error "Attribute value must be constant". Isn't null constant??? @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) public @interface SomeInterface { Class<? extends Foo> bar() default null;// this doesn't compile } 回答1: I don't know why, but the JLS is very clear: Discussion Note that null is not a legal element value for any element type. And the definition of a default element is: DefaultValue: default ElementValue Unfortunately I keep finding that the new

问题 This question already has answers here : Programmatic equivalent of default(Type) (13 answers) Closed 6 years ago . If I want a method that returns the default value of a given type and the method is generic I can return a default value like so: public static T GetDefaultValue() { return default(T); } Can I do something similar in case I have the type only as a System.Type object? public static object GetDefaultValue(Type type) { //??? } 回答1: Since you really only have to worry about value

问题 Possible Duplicate: DEFAULT clause in ALTER TABLE statement resulting in syntax error I am trying to execute the following statement using a SQL query within MS Access; ALTER TABLE [table] ALTER COLUMN [column] SET DEFAULT 'default value' However, I get a dialog displaying the error Syntax error in ALTER TABLE statement. And when I click OK it highlights the word DEFAULT . I also tried the following statement; ALTER TABLE [table] ADD CONSTRAINT [Default] DEFAULT 'default value' FOR [column]

问题 Possible Duplicate: DEFAULT clause in ALTER TABLE statement resulting in syntax error I am trying to execute the following statement using a SQL query within MS Access; ALTER TABLE [table] ALTER COLUMN [column] SET DEFAULT 'default value' However, I get a dialog displaying the error Syntax error in ALTER TABLE statement. And when I click OK it highlights the word DEFAULT . I also tried the following statement; ALTER TABLE [table] ADD CONSTRAINT [Default] DEFAULT 'default value' FOR [column]

问题 I would like to change how default(T) behaves for certain classes. So instead of returning null for my reference types I would like to return a null object. Kind of like kids.Clear(); var kid = kids.Where(k => k.Age < 10).SingleOrDefault(); if (kid is NullKid) { Console.Out.WriteLine("Jippeie"); } Anyone know if this is at all possible? 回答1: Anyone know if this is at all possible? It is simply not possible at all. But maybe you want to use DefaultIfEmpty instead: kids.Clear(); var kid = kids

问题 When declaring primitives/objects, are them initialized? Which are the default value? What is the behavior on class members and local fields ? What about objects declaration on class members? As answered below, these are the default values: Data Type - Default Value (for fields) byte 0 short 0 int 0 long 0L float 0.0f double 0.0d char '\u0000' String (or any object) null boolean false Please note that objects are initialized as null 回答1: The default value of int is 0 and that is the value it