c++ - Why does std::abs return signed types -


i'm getting warning signed vs. unsigned comparison when i'm comparing std::abs(int) against unsigned. , indeed, std::abs returns signed values. why choice made? have solved problem of negative values absolute value cannot represented in signed type.

and then, there cleaner (i.e., without cast) avoid warnings?

#include <cassert> #include <cstdlib>  // max(1, lhs + rhs). (lhs must > 0) unsigned add(unsigned lhs, int rhs) {   return     (0 < rhs || static_cast<unsigned>(-rhs) < lhs      ? rhs + lhs      : 1); }  int main() {   assert(add(42, -41) == 1);   assert(add(42, 0) == 43);   assert(add(42, 1) == 43);   assert(add(42, -51) == 1); }

the short answer done return type of abs same input type. want, of time.

mostly, when calling abs, you're dealing equation elements of same type (or you'd warnings) , want use magnitude of variable in equation. doesn't mean want change type of 1 of variables in equation. give kind of issues/warnings you're mentioning.

so, in short, more common , more natural want same input , output type when asking absolute value of signed variable. magnitude of value isn't commonly used index.


Comments

Post a Comment

Popular posts from this blog

Why does Ruby on Rails generate add a blank line to the end of a file? -

running rails generate controller foo home results in: class foocontroller < application controller def home end end (there's nothing on line in actual file, blank line) is there purpose blank line? it's common use newline indicate end of line, last line. many editors (like vi, use) add in newline silently. consensus text files (especially in unix world) should end in newline, , there have been problems historically if wasn't present. why should text files end newline? the tool used count lines in file "wc" counts newlines in file, without trailing newline show 3 instead of 4. it improves readability of templates used in generator. consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb to remove trailing newline, template have last line of: end<% end -%> instead of: end <% end -%> that seems less readable me. the discussion below refers ...
Read more

node.js - Bad Request - node js ajax post -

i'm using express 3.0 , node v0.11.0. have button submits form , i'm using ajax post data json object node server. client code is: $('#contact').submit(function(e) { console.log('submit called'); var formdata = json.stringify($('form').serializeobject()); console.log(formdata); $.ajax({ url: "http://localhost:3000/savedata/", type: "post", datatype: 'json', data: {objectdata: formdata}, contenttype: "application/json", complete: function() { console.log('process complete'); }, success: function(data) { console.log('process sucess'); }, error: function() { console.log('process error'); }, }); return false; }); then on server: var express = require('express'); var app = express(); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyparser());...
Read more

uitableview - Create and use custom prototype table cells in xamarin ios using storyboard -

Image
is possible create , use 'custom' prototype table cells in xamarin ios (monotouch) using storyboard? i find stuart lodge explaining method using xib/nibs: http://www.youtube.com/watch?feature=player_embedded&v=vd1p2gz8jfy let's answer question! looking one. :) 1) open storyboard have viewcontroller tableview: add prototype cell (if there no cell added before): customize cell want (in case there custom uiimage , label): remember set height of cell. select whole tableview , properties window select "layout" tab. on top of properties window should see "row height" - put appropriate value: now select prototype cell once again. in properties window type name of class (it create code-behind class it). in case "friendscustomtableviewcell". after provide "identifier" cell. can see "friendcell". last thing set "style" property set custom. "name" field should empty. once click ...
Read more