char x=ascii;
queue<pair<char,pair<int,int> > >;
q.push(x,i,j);
I am trying to store a character and it's address(in 2-D array).
What is the syntax to push in queue in such circumstances?
I didn't understand your question completely. But if you are interested to push data in queue<pair<char,pair<int,int> > > , try this:
char x='a';
queue<pair<char,pair<int,int> > > qu;
qu.push(make_pair(x, make_pair(1,2)));
To understand more about make_pair refer to the this link
Related
I would like to write a snippet in VS Code that writes a "switch" expression (in Javascript), but one where I can define the number of cases.
Currently there is a snippet that produces the outline of a switch expression with 1 case, and allows you to tab into the condition, case name, and the code contained within.
I want to be able to type "switch5" ("5" being any number) and a switch with 5 cases to be created, where I can tab through the relevant code within.
I know the snippets are written in a JSON file, can I include such conditional logic in this, or is it not possible?
Thanks!
The short answer is that you cannot do that kind of thing in a standard vscode snippet because it cannot dynamically evaluate any input outside of its designated variables with some limited workarounds like I'll mention next.
You might - I and others have written answers on SO about his - type your various case values first and then trigger a snippet tat would transform them into a switch statement. It is sort of doing it backwords but it might be possible.
There are extensions, however, that do allow you to evaluate javascript right in a snippet or setting and output the result. macro-commander is one such extension. I'll show another simpler extension doing what you want: HyperSnips.
In your javascript.hsnips:
snippet `switch(\d)` "add number of cases to a switch statement" A
``
let numCases = Number(m[1]) // 'm' is an array of regex capture groups
let caseString = ''
if (numCases) { // if not 'switch0'
let tabStopNum = 1
caseString = `switch (\${${tabStopNum++}:key}) {\n`
for (let index = 0; index < m[1]; index++) {
caseString += `\tcase \${${tabStopNum++}:value}:\n\t\t\$${tabStopNum++}\n`
caseString += '\t\tbreak;\n\n'
}
caseString += '\tdefault:\n'
caseString += '\t\tbreak;\n}\n'
}
rv = `${caseString}` // return value
``
endsnippet
The trickiest part was getting the unknown number of tabstops to work correctly. This is how I did it:
\${${tabStopNum++}:key}
which will resolve to ${n:defaultValue} where n gets incremented every time a tabstop is inserted. And :defaultValue is an optional default value to that tabstop. If you don't need a defaultValue just use \$${tabStopNum++} there.
See https://stackoverflow.com/a/62562886/836330 for more info on how to set up HyperSnips.
This code contains an AABB Tree which is build using a Polyhedron_3 mesh. It is possible to verify if an intersection occures but not what primitive the intersection hit. How can I retrieve the primitive?
typedef CGAL::Polyhedron_3<Kernel> Polyhedron;
const Polyhedron& mesh;
tree(faces(_mesh).first, faces(_mesh).second, _mesh);
boost::optional<Primitive_id> intersection = tree.first_intersected_primitive(ray);
if(intersection)
{
//how to get the primitive?
}
Edit:
faces(mesh, tree);
faces(*mesh, tree);
faces(hit, tree);
faces(*hit, tree);
Does not work too.
Edit2:
CGAL::internal::In_place_list_iterator<CGAL::HalfedgeDS_in_place_list_face<CGAL::I_Polyhedron_facet<CGAL::HalfedgeDS_face_base<CGAL::HalfedgeDS_list_types<CGAL::Simple_cartesian<double>, CGAL::I_Polyhedron_derived_items_3<CGAL::Polyhedron_items_3>, std::allocator<int> >, CGAL::Boolean_tag<true>, CGAL::Plane_3<CGAL::Simple_cartesian<double> > > > >, std::allocator<CGAL::HalfedgeDS_in_place_list_face<CGAL::I_Polyhedron_facet<CGAL::HalfedgeDS_face_base<CGAL::HalfedgeDS_list_types<CGAL::Simple_cartesian<double>, CGAL::I_Polyhedron_derived_items_3<CGAL::Polyhedron_items_3>, std::allocator<int> >, CGAL::Boolean_tag<true>, CGAL::Plane_3<CGAL::Simple_cartesian<double> > > > > > > it = *hit;
CGAL::I_Polyhedron_facet<CGAL::HalfedgeDS_face_base<CGAL::HalfedgeDS_list_types<CGAL::Simple_cartesian<double>, CGAL::I_Polyhedron_derived_items_3<CGAL::Polyhedron_items_3>, std::allocator<int> >, CGAL::Boolean_tag<true>, CGAL::Plane_3<CGAL::Simple_cartesian<double> > > >::Halfedge_around_facet_circulator ipfacet = it->facet_begin();
Gets you an iterrator and I_Polyhedron_facet.
Cgal is realy missing some documentation.
Here is the solution: Get the iterator around the face verticess primitive_id->facet_begin(); . And then do this.
Ray_intersection hit = tree.first_intersection(rays[this->transformCoordinates(y,x)]);
if(hit)
{
const Point& point = boost::get<Point>(hit->first);
const Primitive_id& primitive_id = boost::get<Primitive_id>(hit->second);
Polyhedron::Halfedge_around_facet_circulator facerunner = primitive_id->facet_begin();
Point p1;
Point p2;
Point p3;
p1 = facerunner->vertex()->point();
facerunner++;
p2 = facerunner->vertex()->point();
facerunner++;
p3 = facerunner->vertex()->point();
Vector v1(p1,p2);
Vector v2(p1,p3);
Vector n = CGAL::cross_product(v1,v2);
n = n/ std::sqrt(n.squared_length());
}
Answer from the cgal mailinglist:
what are you looking for that is not available here:
https://doc.cgal.org/latest/AABB_tree/index.html#title6
Also note that from here:
https://doc.cgal.org/latest/AABB_tree/classCGAL_1_1AABB__face__graph__triangle__primitive.html
you have:
typedef boost::graph_traits< FaceGraph >::face_descriptor Id
From that same page, you see that the graph type is model of FaceGraph:
https://doc.cgal.org/latest/BGL/classFaceGraph.html
Depending on the type of graph chosen, you have access to the precise
documentation of what face_descriptor corresponds to:
https://doc.cgal.org/latest/BGL/group__PkgBGLTraits.html
Then you can refer to the documentation of the class to know how to
iterate over the vertex of the face.
There is even a generic helper function to do it:
for ( boost::graph_traits<Graph>::vertex_descriptor v :
CGAL::vertices_around_face(halfedge(f, g), g))
{
Point_3 p = get(boost::vertex_index, v, g);
}
I'm not saying it is easy to get but reading the doc gives you the
information required. It's not like reading vtk doc where you have
to guess or read the source code to understand things.
Anyway, we are always looking to improve our doc and we'll be soon
having some cross-packages tutorials and one about manipulation of
surface meshes in CGAL will surely be added.
if intersection is not null, then *intersection should be the Primitive_id of the primitive you are looking for.
With the new ASC 2.0 compiler I get warnings when I code like below:
// (_achievementsFromServer is an Array)
while(item=_achievementsFromServer.pop())
{
// do something with item here
}
The warning reads: "Assignment within conditional. Did you mean == instead of =?"
While in general I appreciate all warnings from the compiler, I'd like to suppress this one in this case because I did not mean == here. I want to pop all items in the array and do something with it until the array is empty.
while( (item=_achievementsFromServer.pop())==true )
seems to work but looks a bit confusing. Any other ideas?
This may seem better.
while(_achievementsFromServer.length > 0) {
var item:Object = _achievementsFromServer.pop();
}
Just like removeChild
var d:DisplayObjectContainer;
while(d.numChildren > 0) {
d.removeChildAt(0);
}
While I was hoping for some other way, I think #AmyBlankenship improved my own suggestion:
while((item=_achievementsFromServer.pop())!=null)
{
//....
}
It's clear and understandable what's going on, and doesn't rely on checking the length of the Array on every iteration.
Googling some more I found a compiler option -compiler.warn-assignment-within-conditional that could be set to false but then you won't be warned anywhere in your project anymore. And I'm not so confident that I never accidently type = instead of ==, so that's not a good solution I think.
This question already exists:
Using Regex in C [closed]
Closed 9 years ago.
I am really desperate. I need to extract all html elements including html tags. I want to retain just plain text. I am required to do this in C. I am discouraged to use Regex. If I use string functions, it just removes delimiters , not the string inside. I need to create a program which extracts plain text from an html file. Any guide would be appreciated on how to do so. Thanks!
Here's a starting point for you:
void remove_html(char* str) {
char* html_str = str;
while(*str) {
if(*html_str == '<')
while(*html_str && *html_str++ != '>');
*str++ = *html_str++;
}
}
int main() {
char foo[] = "hello <p>friends<b>!</b></p>";
remove_html(foo);
puts(foo);
}
It only strips the angular syntax - doesn't do any parsing. Also, it doesn't convert escape characters.
If you open up a html file in notepad, you'll find it is plain text (no images or anything).
All tags start with < and end with >, everything else is text. In this way, you can read through the file only once, excluding the characters that appear between < > symbols.
Pseudocode:
bool intag=false;
for (i=0;i<filesize;i++) {
char c = readchar();
if (c=='<') intag=true;
if (!intag) writechar(c);
if (c=='>') intag=false;
This logic should work for most cases, though you may have to do some more work to deal with indented text and possibly any javascript on the page.
What would be the most readable/best way to write a multiple conditional check such as shown below?
Two possibilities that I could think of (this is Java but the language really doesn't matter here):
Option 1:
boolean c1 = passwordField.getPassword().length > 0;
boolean c2 = !stationIDTextField.getText().trim().isEmpty();
boolean c3 = !userNameTextField.getText().trim().isEmpty();
if (c1 && c2 && c3) {
okButton.setEnabled(true);
}
Option 2:
if (passwordField.getPassword().length > 0 &&
!stationIDTextField.getText().trim().isEmpty() &&
!userNameTextField.getText().trim().isEmpty() {
okButton.setEnabled(true);
}
What I don't like about option 2 is that the line wraps and then indentation becomes a pain. What I don't like about option 1 is that it creates variables for nothing and requires looking at two places.
So what do you think? Any other options?
if (HasPassword() && HasStation() && HasUserName())
okButton.setEnabled(true);
bool HasPassword() {
return passwordField.getPassword().length > 0;
}
etc.
Note that option 1 does not allow for short circuiting behavior. That is, you calculate the value of all of the conditionals before evaluating the result of the first.
I would modify option 1 so that you're using variable names that actually have a meaning. That is, change the name of "c2" to be something like "stationIDIsEmpty" (and move the NOT into the conditional). That way the conditional is readable without having to glance back and forth for every variable.
So my code would probably look like:
boolean enteredPassword = passwordField.getPassword().length > 0;
boolean stationIDIsEmpty = stationIDTextField.getText().trim().isEmpty();
boolean userNameIsEmpty = userNameTextField.getText().trim().isEmpty();
if (enteredPassword && !stationIDIsEmpty && !userNameIsEmpty) {
okButton.setEnabled(true);
}
I voted for Chris Brandsma's answer.
But just wanted to mention the main issue I have with Option 1 is you are losing the benefit of &&. With option one, although I think it's more readable, you are processing comparisons when they may not be required.
Personally, I like the second way, because I find that using that way can make the predication of the conditionals clear. That is, with that method done properly, you can make the conditional comprehensible by "verablizing" it (whether or not you actually speak it is irrelevant).
That is, with your second option, it becomes clear that your conditional translates roughly as this: "If the password length is greater than zero, AND the stationIDTextField (trimmed) is NOT empty, AND the usernameTextField (trimmed) is NOT empty, then..."
I prefer the following:
if (passwordField.getPassword().length > 0
&& ! stationIDTextField.getText().trim().isEmpty()
&& ! userNameTextField.getText().trim().isEmpty())
{
okButton.setEnabled(true);
}
With this coding style I accomplish two things:
I can easily see that each extra line of the if is part of the condition because of the && (or ||) at the beggining.
I can easily see where the if statement ends because of the { at the next line.
Option1 is prime for applying the refactoring 'Replace temp with Query'. The reason being that someone can stuff in code between the variable is initialized and the check and change the behavior of the code. Or the check might be made with stale values.. an update has been made to the textfields between initialization and checking.
So my attempt at this would be
if (GetPasswordLength() > 0
&& FieldHelper.IsNotEmpty(stationIDTextField)
&& FieldHelper.IsNotEmpty(userNameTextField)
{
okButton.setEnabled(true);
}
FieldHelper is a class with public static methods (also called a Utility class / Static class in C#)