Top "Undefined" questions

Undefined offset while accessing array element which exists

I have an array and PHP and when I print it out I can see the values I need to …

php arrays indexing element undefined

I'm new to Prolog. Trying to run this code but gives - ERROR: Undefined procedure: teaches/2 (DWIM could not correct goal)

These are the facts I have written instructor(ahmed,mohammed, cs101,01). instructor(sara,salah,cs101,02). instructor(maryam,faisal,cs101,03). instructor(…

prolog undefined procedure

Having a libpthread.so linking trouble on Ubuntu

I've downloaded source code from this site http://mnbayazit.com/406/bayazit This project has some dependencies: Libraries: FTGL (for fonts), …

ubuntu makefile undefined glfw

ReactNative Flatlist - RenderItem not working

So I'm trying to use React Native's FlatList renderItem property, but something very strange is happening. The data property is …

javascript react-native undefined react-native-flatlist

Can a sass @mixin accept an undefined number of arguments?

I'm trying to create a sass mixin for transitions. This is what I have so far. @mixin transition($var) -webkit-transition: $…

undefined sass arguments mixins

JSSOR - Cannot read type property 'currentStyle' of undefined

I'm trying to implement the Jssor slider into my page, but I keep coming up with that error in the …

javascript undefined jssor

VueJs v-for how to check list undefined before continue

Refer to the template below, how to add condition to make sure the menu is not undefined inside the v-for …

vue.js conditional undefined v-for

NoMethodError in Users#index 'undefined method `each' for nil:NilClass'

I'm getting a NoMethodError in Users#Index with an 'undefined method `each' for nil:NilClass' for the line below: <% @…

ruby-on-rails ruby-on-rails-4 undefined nomethoderror

Is null considered zero and undefined not a number on arithmetic expressions?

Is null evaluated to 0 and undefined to NaN on arithmetic expressions? According to some testing it seems so: > null + …

javascript null undefined nan zero

Waypoints always giving "undefined is not a function/object" errors

I’m trying to use Waypoints to do a very simple scrolling effect, but for some reason, I just simply …

jquery function document undefined jquery-waypoints