global-variables interview questions
Top global-variables frequently asked interview questions
If I create a global variable in one function, how can I use that variable in another function?
Do I need to store the global variable in a local variable of the function which needs its access?
Source: (StackOverflow)
I want to define a constant that should be available in all of the submodules of a package. I've thought that the best place would be in in the __init__.py file of the root package. But I don't know how to do this. Suppose I have a few subpackages and each with several modules. How can I access that variable from these modules?
Of course, if this is totally wrong, and there is a better alternative, I'd like to know it.
Source: (StackOverflow)
I am a newbie in R programming. Though I am poking into the manuals, I also wanted to ask the community "How can we set global variables inside a function?"
Any pointers will help.
Question-2: Regarding plotting,
I am using plotting multiple graphs in a single sheet, and to differentiate each one of them, I want to add title for each one of them. Can anyone tell me how I can achieve this?
Source: (StackOverflow)
function foo () {
global $var;
// rest of code
}
In my small PHP projects I usually go the procedural way. I generally have a variable that contains the system configuration, and when I nead to access this variable in a function, I do global $var;.
Is this bad practice?
Source: (StackOverflow)
I need a few global variables that I need in all .js files.
For example, consider the following 4 files:
global.jsjs1.jsjs2.jsjs3.js
Is there a way that I can declare 3 global variables in global.js and access them in any of the other 3 .js files considering I load all the above 4 files into a HTML document?
Can someone please tell me if this is possible or is there a work around to achieve this?
Source: (StackOverflow)
How can I create global variables that are shared in C? If I put it in a header file, then the linker complains that the variables are already defined. Is the only way to declare the variable in one of my C files and to manually put in externs at the top of all the other C files that want to use it? That sounds not ideal.
Source: (StackOverflow)
A bunch of my JavaScript code is in an external file called helpers.js. Inside the HTML that calls this JavaScript code I find myself in need of knowing if a certain function from helpers.js has been called.
I have attempted to create a global variable by defining:
var myFunctionTag = true;
In global scope both in my HTML code and in helpers.js.
Heres what my html code looks like:
<html>
...
<script type='text/javascript' src='js/helpers.js'></script>
...
<script>
var myFunctionTag = false;
...
//I try to use myFunctionTag here but it is always false, even though it has been se t to 'true' in helpers.js
</script>
Is what I am trying to do even feasible?
Source: (StackOverflow)
We all know that global variables are anything but best practice. But there are several instances when it is difficult to code without them. What techniques do you use to avoid the use of global variables?
For example, given the following scenario, how would you not use a global variable?
JavaScript code:
var uploadCount = 0;
window.onload = function() {
var frm = document.forms[0];
frm.target = "postMe";
frm.onsubmit = function() {
startUpload();
return false;
}
}
function startUpload() {
var fil = document.getElementById("FileUpload" + uploadCount);
if (!fil || fil.value.length == 0) {
alert("Finished!");
document.forms[0].reset();
return;
}
disableAllFileInputs();
fil.disabled = false;
alert("Uploading file " + uploadCount);
document.forms[0].submit();
}
Relevant markup:
<iframe src="test.htm" name="postHere" id="postHere"
onload="uploadCount++; if(uploadCount > 1) startUpload();"></iframe>
<!-- MUST use inline JavaScript here for onload event
to fire after each form submission. -->
This code comes from a web form with multiple <input type="file">. It uploads the files one at a time to prevent huge requests. It does this by POSTing to the iframe, waiting for the response which fires the iframe onload, and then triggers the next submission.
You don't have to answer this example specifically, I am just providing it for reference to a situation in which I am unable to think of a way to avoid global variables.
Source: (StackOverflow)
I'm trying to host a PHP web site that was given to me. I see this warning:
Warning: Unknown: Your script possibly
relies on a session side-effect which
existed until PHP 4.2.3. Please be
advised that the session extension
does not consider global variables as
a source of data, unless
register_globals is enabled. You can
disable this functionality and this
warning by setting
session.bug_compat_42 or
session.bug_compat_warn to off,
respectively. in Unknown on line 0
What does this mean? How might I track down the source of this problem within the code?
Source: (StackOverflow)
We have a lot of setup JS code that defines panels, buttons, etc that will be used in many other JS files.
Typically, we do something like:
grid.js
var myGrid = .....
combos.js
var myCombo = .....
Then, in our application code, we:
application.js
function blah() {
myGrid.someMethod()
}
someother.js
function foo() {
myCombo.someMethod();
myGrid.someMethod();
}
So, should we be using the var myGrid or is better to use window.myGrid
What's the difference?
Source: (StackOverflow)
When I use code like this, it works fine:
function removeWarning() {
var systemStatus = document.getElementById("system-status");
systemStatus.innerHTML = "";
}
function indicateInvalidUsername() {
var systemStatus = document.getElementById("system-status");
systemStatus.innerHTML = "Invalid username";
}
However, when I then want to move the systemStatus to be a global variable, it doesn't work:
var systemStatus = document.getElementById("system-status");
function removeWarning() {
systemStatus.innerHTML = "";
}
function indicateInvalidUsername() {
systemStatus.innerHTML = "Invalid username";
}
What am I supposed to be doing here?
Source: (StackOverflow)
What do I pass as the first parameter "object" to the function setattr(object, name, value), to set variables on the current module?
For example:
setattr(object, "SOME_CONSTANT", 42);
giving the same effect as:
SOME_CONSTANT = 42
within the module containing these lines (with the correct object).
I'm generate several values at the module level dynamically, and as I can't define __getattr__ at the module level, this is my fallback.
Source: (StackOverflow)
What’s the best naming prefix for a global variable?
//
I saw this joke on the wall in my CS lab and, being fairly inexperienced in C++, didn't get it.
Could someone explain it to me?
Source: (StackOverflow)
I wrote the following code:
Function find_results_idle()
Public iRaw As Integer
Public iColumn As Integer
iRaw = 1
iColumn = 1
And I get the error message:
"invalid attribute in Sub or Function"
Do you know what I did wrong?
I tried to use Global instead of Public, but got the same problem.
I tried to declare the function itself as `Public, but that also did no good.
What do I need to do to create the global variable?
Source: (StackOverflow)
Here are 2 files:
// main.js
require('./modules');
console.log(name); // prints "foobar"
// module.js
name = "foobar";
When I don't have "var" it works. But when I have:
// module.js
var name = "foobar";
name will be undefined in main.js.
I have heard that global variables are bad and you better use "var" before the references. But is this a case where global variables are good?
Source: (StackOverflow)