custom-data-type | 易学教程

Why does ('1'+'1') output 98 in Java? [duplicate]

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问题 This question already has answers here : In Java, is the result of the addition of two chars an int or a char? (8 answers) Closed 3 months ago . I have the following code: class Example{ public static void main(String args[]){ System.out.println('1'+'1'); } } Why does it output 98 ? 回答1: In java, every character literal is associated with an ASCII value. You can find all the ASCII values here '1' maps to ASCII value of 49. thus '1' + '1' becomes 49 + 49 which is an integer 98. If you cast

How to modify fields of a nested custom data type with lenses, when modifications depend on indices

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问题 Considering the following : {-# LANGUAGE TemplateHaskell #-} import Control.Lens data Typex = Typex { _level :: Int , _coordinate :: (Int, Int) , _connections :: [(Int,(Int,Int))] } deriving Show makeLenses ''Typex initTypexLevel :: Int -> Int -> Int -> [Typex] initTypexLevel a b c = [ Typex a (x, y) [(0,(0,0))] | x <- [0..b], y <- [0..c] ] buildNestedTypexs :: [(Int, Int)] -> [[Typex]] buildNestedTypexs pts = setConnections [ initTypexLevel i y y | (i,(_,y)) <- zip [0..] pts ] setConnections

How to modify fields of a nested custom data type with lenses, when modifications depend on indices

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Compiler error while calling template functions

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问题 I'm getting the following error upon compiling: Compilation started at Wed Oct 5 03:05:32 |make -k proj1 |g++ proj1.cc -o proj1 |proj1.cc: In function ‘int main()’: |proj1.cc:75:13: error: no matching function for call to ‘getData()’ |proj1.cc:75:13: note: candidate is: |proj1.cc:46:6: note: template<class T> void getData(Vector<T>&, int&) |proj1.cc:80:16: error: no matching function for call to ‘computeSum()’ |proj1.cc:80:16: note: candidate is: |proj1.cc:28:6: note: template<class T> void

c++ Copy constructors and destructors

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问题 I am learning constructors and Destructors in c++; Help me grasp my mistakes even if they are silly... HERE is a code I have written to perform addition using classes in c++; This creates two summands of datatype num and employs the constructor sum() to perform sum of the two numbers; However when everything was goin' alright, I stumbled upon creating a copy constructor for num , (Although not necessary but still for practice)... without the dynamic object of the class sum it is not possible

oracle procedure returning table of custom data type record

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问题 I created a custom data type of the type "object" create type myrecord is object(col1 varchar2(10),col2 varchar2(10)); I created a table which is of the type record create type mytableobject is table of myrecord; Now i have filled the table "mytableobject" with data using "execute immediate" (select * from table1) bulk collect into mytableobject. I want to return this mytableobject in a STORED procedure. How do i achieve this? And how do i call the procedure? 回答1: You can use your own type as

Custom data type (Structures) vs arrays

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问题 I have a combo box that, when selected, displays text in 3 text boxes. The combo box items are the 50 states, and the text boxes display information on state statutes. Right now I'm using a multidimensional array to hold the data for each state (each item in the array holds the state, item 1, item 2, item 3). My question is: Would it be better or more compact to create a State data type that holds the 3 items, and actually if this is even an effective approach? I don't like the array, it's

access composite array elements plpgsql

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问题 I have a array of user-defined composite data type. I need to do some manipulation on the array elements in plpgsql function but I'm not getting the syntax right to access the individual elements. Any help is appreciated. Pasted below is simplified version of the code. CREATE TYPE playz AS( a integer, b numeric, c integer, d numeric); CREATE OR REPLACE FUNCTION playx(OUT mod playz[]) AS $$ BEGIN FOR i in 1..5 LOOP mod[i].a = 1; mod[i].b = 12.2; mod[i].c = 1; mod[i].d = 0.02; END LOOP; END; $$

Defining DataRange Expression in Protege for a Data Type Property

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问题 I am adding few new DataType in the OWL using Protege. The DataType is like percentage and I want to specify it's range with the double value ranging from 0 to 100. Similarly a DataType named Quality and I want to specify it's range with the double value ranging from 0 to 1. How can we specify these things in the Data range Expression ? I tried to find out but I found two links but not useful in my context. How to Define My Own Ranges for OWL DataProperties This is useful if we are manually

Rails migrations with database-specific data types

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I'm currently running a Rails migration where I am adding a datatype specific to Postgres, the tsvector. It holds search information in the form that Postgres expects for its built-in text searching capabilities. This is the line from my migration: t.column "search_vectors", :tsvector Everything seems to be working fine, and the search works with it. However, when I opened up schema.rb, this is what I got: Could not dump table "users" because of following StandardError Unknown type 'tsvector' for column 'search_vectors' This is preventing me from running unit tests on the user table, and also