's questions

From a string I need to know how many characters there are without counting spaces or numbers and send it to print, as well as another function that tells me if there are numbers and how many of that same string, even without spaces, this is what I have done so far.

I already get how many characters but I don't want it to count the numbers, I want them separately:

function  cadenaNumerosLetras(){
    var frase = document.getElementById(‘cadena’).value;
    var letterCount = frase.split(/\W/).join('').length;
    var contadorLetras = letterCount.toString();
    console.log(letterCount);
    document.getElementById(‘resultado’).value = contadorLetras;
    var numeros = "0123456789";
    if(!isNaN(frase)){
        for(i=0; i<frase.length;i++){
            if(numeros.indexOf(frase.charAt(i),0)!=-1){
                return 1;
                document.getElementById('numeros').innerHTML= frase;
            }
        }
        return 0;          
    }  
}

I have an example where I don't quite understand. What is the optimal way to solve it?

A table called usuarios.

A table called publicaciones.

If I plan to save the records of a post with that idof the user who registered it; is the following structure correct?

But for example considering that an intermediate table called publicaciones-usuarioswith a structure similar to the following could be created:

What is the optimal way?, since for example if I make the first structure with a inner joinlike the following:

SELECT titulo, cuerpo, username FROM publicaciones
INNER JOIN usuarios
ON usuarios.id = publicaciones.usuarios_id
WHERE usuarios.id = 2;

I can extract the publications that a user makes taking into account that the link between both tables is that idof the user as a foreign key in the table publicaciones; but I don't quite understand under what scenarios each one is used

It is just an example considering that I seek to clarify this doubt

What I'm trying to do is leave a background shadow that passes from left to right. What the background does is give it another background color, but instead of it appearing, it moves. modify everything. Now I did this:

.Grupo {
  transition: all 0.5s ease-out;
  transition-timing-function: linear;
}

.Grupo:hover {
  background: #C7212F !important;
}

<div id="area-vulnerables" class="Grupo">
  <a href="" title="">
    <div class="area-icon">
      Contenido
    </div>
  </a>
</div>

Well, everything even works fine, but what I want to do and it doesn't work out for me is that the transition is from left to right. How can I do it?

Can data attributes be created followed by a number, data-0 = "mexico"?

Or something like this:

data-data1 = "mexico" 

The idea is to retrieve them through an iteration and thus save yourself from writing attribute by attribute.

The pseudo-class :nth-childis often used in tables or lists to differentiate even rows from odd ones:

li:nth-of-type(2n) {
  background-color: #ccc;
}

<ul>
  <li>elemento1</li>
  <li>elemento2</li>
  <li>elemento3</li>
  <li>elemento4</li>
</ul>

Or to select a specific child element:

li:nth-of-type(3) {
  background-color: #F00;
}

<ul>
  <li>elemento1</li>
  <li>elemento2</li>
  <li>elemento3</li>
  <li>elemento4</li>
</ul>

However, it has a more complex syntax, I have seen cases of this style:

p:nth-child(4n+2)

I don't quite understand what exactly it does and what practical uses it can have.

I have a big question about relationships in mysql. You see, I'm creating a site that looks like an e-commerce, it's for a colleague.

I am creating a table called categories and another called subcategories . In the subcategories table I have a column called categoria_id, which will contain the ID of the selected category. Then like this, I will be able to show the subcategories with their respective categories.

An example: Cell Phone Accessories (category), Chargers (subcategory) and so on.

Is it necessary to create a relationship between the category ID, and the category_id of the "subcategories" table? I hope I have explained myself correctly.

Greetings.

I have to process a lot of sentences. In fact, the number of them is unlimited : they are obtained from a source on the Internet.

The goal is to count how many times a certain phrase is repeated. Since the number of them is, as I say, unlimited , it is obvious that I cannot store all of them in memory.

Additionally, certain conditions are required of me: the complexity of any operation must be O(1). There 's no mention of collisions, so I'm neglecting them for now.

An example of the expected behavior :

1. 4096 sentences are read, all of them different . Coincidentally, neither generates hash collision with another.

2. The hash table is filled . The 4096 gaps are occupied by the sentences read.

3. A new sentence is read. Its hash is the same as one of the previous phrases, but the phrase is different from all the 4096previous ones.

4. I remove from the table the item that has been unused the longest . In this case, it would be the first one I inserted . I don't remove the element with matching hash value, because it is more modern .

EDIT

Currently, I have this:

#include <string.h>

typedef struct phrase_s {
  char text[256];
  unsigned long long count;
  struct phrase_s *prev;
  struct phrase_s *next;
} Phrase;

Phrase List[4096];

// Devuelve la hash de una cadena, limitada a 12 bits ( 0 - 4095 ).
size_t makeHash( const char * );
// Devuelve la cadena MAS ANTIGUA, aquella que hay que eliminar.
Phrase *old( void );


void addString( const char *str ) {
  size_t hash = makeHash( str );

  if( !( List[hash].count ) ) {
    // Caso fácil. No hay cadenas con hash coincidente.
    memcpy( &( List[hash].text ), str, strlen( str ) );
    List[hash].count = 1;
    List[hash].prev = NULL;
    List[hash].next = NULL;

    return;
  }

  // Caso INTERESANTE. La hash COINCIDE con otra.
  // POR HACER.
}

How do I implement point 4 above? Can I continue from the code I already have, or are other modifications necessary?

I reiterate the issue of complexity. The number of operations to perform must be independent of the size of the table.

_{Note: This is a question that was posted a couple days ago and I found it interesting. It is what I could understand with some sense of it, which has been eliminated by its author.}

EDIT 2

I still find it an interesting question; surely there are more good answers, which show the logic to follow in these cases. I add the language C++to the allowed responses.

EDIT 3

As I have been told, the term must be specified O( 1 ). Normally, it would indicate a constant complexity . Since we're talking about a hash table, we'll add the mean tagline ; that is, the chosen algorithm must have, on average , complexity O( 1 ).

Also, to be able to use std::unordered_map, responses in C++11 are supported.

What does the value mean in the tag javascript:void(0)fields in ?hrefaHTML

Example:

<a href="javascript:void(0)" id="btnClick">Click</a>

In PHP what is this for?

<?=
?>

And what is the difference with respect to this form?

<?php
?>

If I try to display the length of an array in C++ , using the function sizeof, it correctly displays the result, which in this case is 8.

int main()
{
    int array_enteros[]={'9','8','7','6','5','4','3','2'};
    int longitud=sizeof(array_enteros)/sizeof(*array_enteros);
    cout<<longitud<<endl;
    return 0;
}

What I don't like is that you have to enter the word array_enterostwice to know the length, and for this, it would be better to get it through a function.

int obtener_longitud_array(int* array_enteros)
{
    return sizeof(array_enteros)/sizeof(*array_enteros);
}
int main()
{
    int array_caracteres_enteros[]={'9','8','7','6','5','4','3','2'};
    int longitud=obtener_longitud_array(array_caracteres_enteros);
    cout<<longitud<<endl;
    return 0;
}

In this case, it returns 1, which is a different value.

Will there be any problem in the parameters of the function?

I want to have a Javascript function that uses regular expressions to add things to the borders of certain words in a text.

Example, I want to replace this:

The swift Indian bat happily ate thistle and kiwi. The stork played the saxophone...

... for the following, knowing that the keywords are swift , thistle and kiwi :

The <b>fast</b> Indian bat happily ate <b>thistle<b> and <b>kiwi</b>. The stork played the saxophone...

I'm programming in JavaScript and HTML , and I have a textArea (textarea) , and a divwhere I show that I resultadohave processed the content of the textArea.

But what I want is to process the selected text . That is, he resultadois:

Mark in bold and large size the selected part.

My code is the following:

function procesar_selección(texto)
{
  return texto
}
function procesar_selección_html()
{
  var texto = document.getElementById("texto_html").value
  resultado.innerHTML = procesar_selección(texto)
}

textarea{
  height: 100px;
  width : 400px;
}

<div>Escriba el texto a procesar:</div>
<textarea
  id = "texto_html"
  onkeyup   = "procesar_selección_html()"
  onkeydown = "procesar_selección_html()" >
</textarea>
<div id="resultado" ></div>

Last week, that is, on February 13, 2017, I asked a question.

How to sort a two dimensional array by columns in Javascript?

But that works for sorting a single column. When two elements of the column to sort are the same, it should be able to sort that sector by another column, but it doesn't.

The array I want to sort is the following:

var matriz = [
//Columnas:    0 1 2 3 4
/*Filas:  0*/ [9,5,3,2,7],
/*        1*/ [7,9,5,4,3],
/*        2*/ [8,4,6,0,1],
/*        3*/ [9,9,6,2,1]
             ]

With the current algorithm, sorting column 3 , the answer is as follows:

var matriz = [
//Columnas:    0 1 2 3 4
/*Filas:  0*/ [7,9,5,4,3],
/*        1*/ [9,5,3,2,7],
/*        2*/ [9,9,6,2,1],
/*        3*/ [8,4,6,0,1]
             ]

It's not too bad, it's sorted 4 2 2 0, but the rows that have the 2 , should be sorted by the columns I want.

To be exact, the function that sorts should receive an array (a sequence) with all the columns that I want to sort, for example, [3,0,1,2,4]. This means that first it sorts by column 3, in case they are equal ( 2 ), it sorts those by 0, but 9 is also the same, so it sorts by 1, and it would be sorted, but just in case, too order by 1, 2 and 4.

Also, to make it more general, it would be good to change whether the column is ascending or descending, for this, instead of an array it should be a matrix, the first column is the number of the column to sort, and the second column is a boolean indicating truewhether it is descending, and falsewhether it is descending.

var columnas = [//  Columna - esDescendente
                  [   3,        true ],
                  [   0,        true ],
                  [   1,        true ],
                  [   2,        false],
                  [   4,        false]
]

With this parameter, the result should be the following:

var matriz = [
//Columnas:    0 1 2 3 4
/*Filas:  0*/ [7,9,5,4,3],
/*        1*/ [9,9,6,2,1],
/*        2*/ [9,5,3,2,7],
/*        3*/ [8,4,6,0,1]
             ]

The sort order is not static, but is generated by a function.

function generar_compara(columna,esDescendente)
{
  var menos=1-2*esDescendente
  var devuelve="return a["+columna+"]>=b["+columna+"]?"+menos+":"+(-menos)
  return Function("a","b",devuelve)
}
console.log(generar_compara(0,true))
console.log(generar_compara(1,false))

According to the arguments that I indicate, it generates a different criterion function for me .

• 0, false->function anonymous(a,b/**/) {return a[0]>=b[0]?-1:1}
• 1, true->function anonymous(a,b/**/) {return a[1]>=b[1]?1:-1}

My question is: How would the criteria be if I want to order, for example, as follows [3,true],[0,true],[1,true],[2,false],[4,false]? and starting from the example function, how can I build a generator of similar functions, to make it more general?

In Python, how can I convert a string "123.456"to a decimal number 123.456? And how a string "32"to an integer 32?

From a String, "123-654321", what I want is to split it into two Strings:

string1=123
string2=654321

I have declared an integer dynamic in Java, that is:

ArrayList<Integer> lista = new ArrayList<Integer>();

... I'm already adding numbers to this one.

lista.add(5); lista.add(7); lista.add(3);

What I want is to order that list, and make it look like this 3, 5, 7, and for that, I tried to use a method called sort, as follows.

lista.sort();

But he asks me for an argument that I don't know. I would like to order it from smallest to largest, although if I can sort it from largest to smallest, it doesn't matter, because then I can flip the list.

The error I have is:

The method sort(Comparator<? super Integer>) in the type ArrayList<Integer> is not applicable for the arguments ()

How do I go about applying that sort method to the list?

I would need to know how to read a character by keyboard in Java .

I know that you can read a number, or a phrase, but this time I would like it to read only one character, and the system to show a message, immediately after pressing that character, and not when I touch Intro.

The following code receives an integer, then I hit Intro, and it saves.

Scanner teclado = new Scanner(System.in);
int número = teclado.nextInt();

But what I want is to save a character without pressing the key. It's possible?

I want to know how to make a JavaScript function that returns the coordinates at a given minute . The central coordinates are the center of the clock, so they can be negative.

In Microsiervos I found a link , which parallels what I'm asking, it's a clock that gives you the time in coordinates .

I'm trying division or subtraction, but it doesn't work.

function(minutos)
{
    var x=0,y=0
    x=minutos*60
    y=x-12
    return [x,y]
}

edit:

Looking at some answers I have seen something strange: Why use cosine , if it is possible to extract in value using sine ?

I have a code as follows:

public class Clase {
    public void hazAlgo(String s) {
        /* implementación */
    }
}

I am now creating a static method in Claseto validate that the string does not contain any trailing spaces. If you have them, you should clean them. In addition to that, the method must be used hazAlgo. So, I have the code like this:

public class Clase {
    public void hazAlgo(String s) {
        /* implementación */
    }

    public static String limpiaCadena(String s) {
        s = (s == null) ? "" : s.trim();
        hazAlgo(s);
    }
}

This code, when compiled, gives me the following error message:

$ javac Clase.java 
Clase.java:8: error: non-static method hazAlgo(String) cannot be referenced from a static context
        hazAlgo(s);
        ^
1 error

What am I doing wrong?

The title is explicit. What fundamental or fundamental difference is there between these methods when defining the functions or methods?

Important: Despite being a very similar question to this one on stackoverflow , it is not intended to be a translation of any of their answers.