constants

问题 Do int const *a and const int *a mean that "a is a integer pointer to a constant value" and "a is a pointer to a constant address", respectively , or is it viceversa? This was asked to me in an interview. After reading a lot about the same I am still very much confused regarding it. 回答1: const int *a - a is writable (can point to a different thing), *a is not writable (cannot write to pointed-to thing) int const *a - same as above int * const a - a is not writeable (cannot point to a

问题 I'm making a program that has a lot of constants. I decided to put them all into a separate class and I'm importing it by the classes that need it. The files look similar to this // Constants.h extern const int baseCostForBuilding; extern const int maxCostForBuilding; // etc // Constants.m const int baseCostForBuilding = 400; const int maxCostForBuilding = 1000; // etc What I'm trying to do is access them using key-value coding. What I've tried so far hasn't worked. id object = [self

问题 Although True , False are builtin constants, the following is allowed in Python. >>> True = False >>> a = True >>> b = False >>> print a,b False False Any reference of why this is allowed? EDIT: This happens only in Python 2.x (as all pointed out). 回答1: Keep in mind that this only happens in versions of Python that were before python 3. This was part of Python's philosophy that everything should be dynamic. In fact in Python 2 True is not a keyword. It is a reference bound to a bool object .

问题 Objective : Declare a comma seperated string constant test.csv ========= a b c d e f Pig Script : %declare ACTIVE_VALUES 'a', 'b','c' ; -- Declaring constant like this using "" (double quotes) or even using escape characters (\) is resulting in a WARN message as below -- WARN org.apache.pig.tools.parameters.PreprocessorContext - Warning : Multiple values found for ACTIVE_VALUES A = LOAD 'test.csv' using PigStorage(',') AS (value:chararray); B = FILTER A BY value in ($ACTIVE_VALUES); dump B;

问题 Sort of a philosophical question, I guess. We are starting a video game project, and discovering C# as we go. One of the first things we need is a way to store constants in a bunch of arrays, so that anyone can access those values easily, and so we can quickly add or modify values as new character or weapon types are defined. Now in C++, this is how I've learned to do it: declare an enum in some constants.h file, with its last element being "WHATEVER_TYPE_END" ; declare constant arrays of

问题 I just started to read the ISO C 2011 standard , well the last public draft of it [1] , and realized that in the C Lexical Grammer [1][458ff.] all (literal) numerical constants are unsigned. Does that mean that the Compiler interpret a signed numerical constant (like -5.1E10 or -1) as a call of the corresponding unary-operator ? e.g -1 <=> -(1) , +512 <=> +(512) UPDATE: My fault, "all (literal) numerical constants are unsigned" I mean "all (literal) numerical constants are non-negative"

问题 This question already has answers here : Can we change the value of an object defined with const through pointers? (10 answers) Closed 3 years ago . Not a Duplicate. Please read Full question. #include<iostream> using namespace std; int main() { const int a = 5; const int *ptr1 = &a; int *ptr = (int *)ptr1; *ptr = 10; cout<<ptr<<" = "<<*ptr<<endl; cout<<ptr1<<" = "<<*ptr1<<endl; cout<<&a<<" = "<<a; return 0; } Output: 0x7ffe13455fb4 = 10 0x7ffe13455fb4 = 10 0x7ffe13455fb4 = 5 How is this

问题 following this question Why doesn't gcc allow a const int as a case expression?, basically the same as What promoted types are used for switch-case expression comparison? or Is there any way to use a constant array with constant index as switch case label in C?. From the first link, I tried to replace : case FOO: // aka 'const int FOO = 10' with : case ((int) "toto"[0]): // can't be anything *but* constant Which gives : https://ideone.com/n1bmIb -> https://ideone.com/4aOSXR = works in C++

问题 Edit: Solutions must compile against Microsoft Visual Studio 2012. I want to use a known string length to declare another string of the same length. The reasoning is the second string will act as a container for operation done to the first string which must be non volatile with regards to it. e.g. const string messy "a bunch of letters"; string dostuff(string sentence) { string organised NNN????? // Idk, just needs the same size. for ( x = 0; x < NNN?; x++) { organised[x] = sentence[x]++; //

问题 I am using an imported class with has constant field values set using: public static final int BLUE = 1; public static final int GREEN = 2; etc. Is there any way of getting a string representation of the constant field value from the int value? i.e. given the value 2 I want to get a string of GREEN. P.S. This isn't my class so I can't use ENUMs 回答1: If you can change the class which contains these constants, it would be better to make it an enum with a value() method. Otherwise, I would