constants

问题 I have a requirement to build an automated system to parse a C++ .h file with a lot of #define statements in it and do something with the value that each #define works out to. The .h file has a lot of other junk in it besides the #define statements. The objective is to create a key-value list, where the keys are all the keywords defined by the #define statements and the values are the evaluations of the macros which correspond to the definitions. The #defines define the keywords with a series

问题 I have a requirement to build an automated system to parse a C++ .h file with a lot of #define statements in it and do something with the value that each #define works out to. The .h file has a lot of other junk in it besides the #define statements. The objective is to create a key-value list, where the keys are all the keywords defined by the #define statements and the values are the evaluations of the macros which correspond to the definitions. The #defines define the keywords with a series

问题 I understand that constant CStrings are allocated statically, rather than on the heap. I also noticed that constant NSStrings have an infinite retain count. Does it hold true that constant NSStrings are also allocated statically, rather than on the heap? 回答1: Constant NSStrings are of class NSConstantString , and thus act like atoms in lisp; they hang around. -> NSConstantStrings are allocated statically. That is, if you use @"cow" in two separate places in your code, they will be referencing

问题 #include <iostream> #include <string> #include <fstream> #include <sstream> #include <vector> #include <iterator> #define ADDR "c:\\Users\\Library2\\Desktop\\Books record\\" using namespace std; int main() { ifstream fin(ADDR "reportcard.csv", ios::binary); string line; int rowCount=0; int rowIdx=0; while(getline(fin,line)){ rowCount++; } vector<string> data[**rowCount**];//this rowCount gave me "expression must have a constant value" fin.clear(); fin.seekg(fin.beg); while(getline(fin,line))

问题 In my julia code I am using some constants. Some of these constants are strings (they serve as identifiers). My issues is that whenever I run a julia script, I always get the following warning for constant strings, even when I do not change the constants : WARNING: redefining constant pot_type To illustrate my problem, here is a MWE: const pot_type = "constant" const b = 12 println("Given parameters: Potential = $pot_type, b = $b .") If I run this script two times, I will get the

问题 I know (from the compiler's errors) that a constant property cannot be overridden by a constant, nor can it be overridden by the getter of a computed property. Obviously they can't be overridden by anything non-constant. There's no reason to add observers to them, either, since they'll never change. And yet final let seems to be a thing. Is it impossible to override a stored constant property? Is final let exactly equivalent to let ? 来源： https://stackoverflow.com/questions/35671819/is-it

问题 Your answers are very much sought to clear this major lacuna in my understanding about const that I realized today. In my program I have used the statement const int *ptr=&i; but haven't used any const qualifier for the variable i .Two things are confusing me: 1) When I try to modify the value of i using ptr ,where I have used const int *ptr=&i; ,I get the error assignment of read-only location '*ptr'| ,even though I haven't declared the variable i with the const qualifier.So what exactly the

问题 I want to have a catalog of constant materials so I can use code that looks like the following: Dim MyDensity, MySymbol MyDensity = ALUMINUM.Density MySymbol = ALUMINUM.Symbol Obviously the density and symbol for aluminum are not expected to change so I want these to be constants but I like the dot notation for simplicity. I see a few options but I don't like them. Make constants for every property of every material. That seems like too many constants since I might have 20 materials each with

问题 I want to have a catalog of constant materials so I can use code that looks like the following: Dim MyDensity, MySymbol MyDensity = ALUMINUM.Density MySymbol = ALUMINUM.Symbol Obviously the density and symbol for aluminum are not expected to change so I want these to be constants but I like the dot notation for simplicity. I see a few options but I don't like them. Make constants for every property of every material. That seems like too many constants since I might have 20 materials each with

问题 What would be a neat way to share configuration parameters\settings\constants between various projects in Python? Using a DB seems like an overkill. Using a file raises the question of which project should host the file in its source control... I'm open for suggestions :) UPDATE: For clarification - assume the various projects are deployed differently on different systems. In some cases in different directories, in other cases some of the projects are there and some are not. 回答1: I find that