undefined

问题 Every time anyone mentions testing against undefined , it's pointed out that undefined is not a keyword so it could be set to "hello", so you should use typeof x == "undefined" instead. This seems ridiculous to me. Nobody would ever do that, and if they did it would be reason enough to never use any code they wrote... right? I found one example of someone who accidentally set undefined to null , and this was given as a reason to avoid assuming that undefined isn't overwritten. But if they'd

问题 I'm a PHP newbie, so I have a minor problem functions. I have this line of code: <?php $ime=$_POST["ime"]; $prezime=$_POST["prezime"]; $pera="string"; if (empty($ime)||empty($prezime)){ echo "Ne radi, vrati se nazad i unesi nesto!"; } function provera($prom){ if (preg_match("/[0-9\,\.\?\>\.<\"\'\:\;\[\]\}\{\/\!\\\@\#\$\%\^\&\*\(\)\-\_\=\+\`[:space:]]/",$prom)){ echo "Nepravilan unos imena ili prezimina!"; echo $pera; } } provera($ime); provera($prezime); ?> Anyway, when I try this code I

问题 We are frequently using the following code pattern in our JavaScript code if (typeof(some_variable) != 'undefined' && some_variable != null) { // Do something with some_variable } Is there a less verbose way of checking that has the same effect? According to some forums and literature saying simply the following should have the same effect. if (some_variable) { // Do something with some_variable } Unfortunately, Firebug evaluates such a statement as error on runtime when some_variable is

问题 How do I determine if variable is undefined or null ? My code is as follows: var EmpName = $("div#esd-names div#name").attr('class'); if(EmpName == 'undefined'){ //DO SOMETHING }; <div id="esd-names"> <div id="name"></div> </div> But if I do this, the JavaScript interpreter halts execution. 回答1: You can use the qualities of the abstract equality operator to do this: if (variable == null){ // your code here. } Because null == undefined is true, the above code will catch both null and undefined

问题 I have a library irWGN dependent of another library irRNG. My CMakeFiles.txt's are as follows. The one is src/signals is add_library(irRNG irRNG.cpp) add_library(irWGN irWGN.cpp) and the main CMakeFile include_directories(${SRC}/signals) SET(MY_LIB ${MY_LIB} irRNG irWGN ) .... foreach(file2link ${FILES_to_RUN}) target_link_libraries(${file2link} ${catkin_LIBRARIES} ${Boost_LIBRARIES} ${gsl_LIBRARIES} ${OpenCV_LIBRARIES} ${MY_LIB} ) add_dependencies(${file2link} project_generate_messages_cpp)

问题 I load js files dynamically in my project putting their content in a script tag in the head. Each file has only an object inside. I noticed that after loading, all objects are in the script tag but only the first is not undefined (the order I put content doesn't change the problem, first is an object, others nope) This is the script window.onload = function () {objMaster.end(objMaster.main());}; objMaster = { // ---------- MAIN main: function () { // Setting up the environment if (!this.set()

问题 I am currently completing a project and am trying to create a menu. The menu itself works alright but when I try and link to the other java file that the method itself is in I get the error "the method method name is undefined for the type String". Below is the code that I am using to try and link to the method in the other java file. { if (menuChoice.equals("A")) { System.out.print("Enter the Movie ID: "); movieID = sc.nextLine(); movieID.borrowMovie(); } if (menuChoice.equals("a")) { System

问题 I am trying to parse text into a date using chronic in ruby. However, I keep running into an error while trying to parse the string. Error: NoMethodError - undefined method 'zone=' for Time:Class: Here is the code: require 'rubygems' require 'sinatra' require 'chronic' require 'date' require 'time' require 'active_support' require 'cgi' require 'json' module TimeAPI ZoneOffset = { 'A' => +1, 'ADT' => -3, 'AKDT' => -8, 'AKST' => -9, 'AST' => -4, 'B' => +2, 'BST' => +1, 'C' => +3, 'CDT' => -5,

问题 I'm currently on Chapter 7 of Hartl's Tutorial, and every time I run bundle exec rspec spec/ the following results: /Users/siciliana/sample_app/spec/spec_helper.rb:31:in `block in <top (required)>': undefined method `infer_base_class_for_anonymous_controllers=' for #<RSpec::Core::Configuration:0x007f7fb3a62b80> (NoMethodError) from /usr/local/rvm/gems/ruby-2.0.0-p0/gems/rspec-core-2.6.4/lib/rspec/core.rb:79:in `configure' from /Users/siciliana/sample_app/spec/spec_helper.rb:11:in `<top

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 5 years ago . I am also having the "undefined reference to ERPSGame()" error as well as the "Id returned 1 exit status". Did I declare something wrong? I am using Orwell Dev C++. What seems to be the problem? Is it my compiler ? Check out the whole code: /* GameBox BETA v0.2 */ #include <stdio.h> #include <conio.h> #include