Programs & Examples On #Sapply

sapply is a command in the R language that applies a function to each element of a vector (atomic or list). It may also accept other classes if they are coercible by the function base::as.list. The sapply function returns a vector by default, however will return a list when more suitable or an array if argument simplify = "array" is specified.

Grouping functions (tapply, by, aggregate) and the *apply family

On the side note, here is how the various plyr functions correspond to the base *apply functions (from the intro to plyr document from the plyr webpage

Base function   Input   Output   plyr function 
aggregate        d       d       ddply + colwise 
apply            a       a/l     aaply / alply 
by               d       l       dlply 
lapply           l       l       llply  
mapply           a       a/l     maply / mlply 
replicate        r       a/l     raply / rlply 
sapply           l       a       laply 

One of the goals of plyr is to provide consistent naming conventions for each of the functions, encoding the input and output data types in the function name. It also provides consistency in output, in that output from dlply() is easily passable to ldply() to produce useful output, etc.

Conceptually, learning plyr is no more difficult than understanding the base *apply functions.

plyr and reshape functions have replaced almost all of these functions in my every day use. But, also from the Intro to Plyr document:

Related functions tapply and sweep have no corresponding function in plyr, and remain useful. merge is useful for combining summaries with the original data.

Apply a function to every row of a matrix or a data frame

Apply does the job well, but is quite slow. Using sapply and vapply could be useful. dplyr's rowwise could also be useful Let's see an example of how to do row wise product of any data frame.

a = data.frame(t(iris[1:10,1:3]))
vapply(a, prod, 0)
sapply(a, prod)

Note that assigning to variable before using vapply/sapply/ apply is good practice as it reduces time a lot. Let's see microbenchmark results

a = data.frame(t(iris[1:10,1:3]))
b = iris[1:10,1:3]
    apply(b, 1 , prod),
    vapply(a, prod, 0),
    sapply(a, prod) , 
    apply(iris[1:10,1:3], 1 , prod),
    vapply(data.frame(t(iris[1:10,1:3])), prod, 0),
    sapply(data.frame(t(iris[1:10,1:3])), prod) ,
    b %>%  rowwise() %>%
        summarise(p = prod(Sepal.Length,Sepal.Width,Petal.Length))

Have a careful look at how t() is being used

Apply function to each column in a data frame observing each columns existing data type

A solution using retype() from hablar to coerce factors to character or numeric type depending on feasability. I'd use dplyr for applying max to each column.



# Retype() simplifies each columns type, e.g. always removes factors
d <- d %>% retype()

# Check max for each column
d %>% summarise_all(max)


Not the new column types.

     v1 v2       v3 v4   
  <dbl> <chr> <dbl> <chr>
1 0.974 j      1.09 J   


# Sample data borrowed from @joran
d <- data.frame(v1 = runif(10), v2 = letters[1:10], 
                v3 = rnorm(10), v4 = LETTERS[1:10],stringsAsFactors = TRUE)

Select value from list of tuples where condition

If you have named tuples you can do this:

results = [t.age for t in mylist if t.person_id == 10]

Otherwise use indexes:

results = [t[1] for t in mylist if t[0] == 10]

Or use tuple unpacking as per Nate's answer. Note that you don't have to give a meaningful name to every item you unpack. You can do (person_id, age, _, _, _, _) to unpack a six item tuple.

Insert into a MySQL table or update if exists

Check out REPLACE

REPLACE into table (id, name, age) values(1, "A", 19)

TypeError: $.browser is undefined

I placed the following html in my code and this cleared up the $.browser error

<script src=""></script>

Hope this helps u

How to prevent null values inside a Map and null fields inside a bean from getting serialized through Jackson

If it's reasonable to alter the original Map data structure to be serialized to better represent the actual value wanted to be serialized, that's probably a decent approach, which would possibly reduce the amount of Jackson configuration necessary. For example, just remove the null key entries, if possible, before calling Jackson. That said...

To suppress serializing Map entries with null values:

Before Jackson 2.9

you can still make use of WRITE_NULL_MAP_VALUES, but note that it's moved to SerializationFeature:

mapper.configure(SerializationFeature.WRITE_NULL_MAP_VALUES, false);

Since Jackson 2.9

The WRITE_NULL_MAP_VALUES is deprecated, you can use the below equivalent:

   JsonInclude.Value.construct(Include.ALWAYS, Include.NON_NULL))

To suppress serializing properties with null values, you can configure the ObjectMapper directly, or make use of the @JsonInclude annotation:



class Foo
  public String bar;

  Foo(String bar)
  { = bar;

To handle null Map keys, some custom serialization is necessary, as best I understand.

A simple approach to serialize null keys as empty strings (including complete examples of the two previously mentioned configurations):

import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.SerializerProvider;

public class JacksonFoo
  public static void main(String[] args) throws Exception
    Map<String, Foo> foos = new HashMap<String, Foo>();
    foos.put("foo1", new Foo("foo1"));
    foos.put("foo2", new Foo(null));
    foos.put("foo3", null);
    foos.put(null, new Foo("foo4"));

    // System.out.println(new ObjectMapper().writeValueAsString(foos));
    // Exception: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?)

    ObjectMapper mapper = new ObjectMapper();
    mapper.configure(SerializationFeature.WRITE_NULL_MAP_VALUES, false);
    mapper.getSerializerProvider().setNullKeySerializer(new MyNullKeySerializer());
    // output: 
    // {"":{"bar":"foo4"},"foo2":{},"foo1":{"bar":"foo1"}}

class MyNullKeySerializer extends JsonSerializer<Object>
  public void serialize(Object nullKey, JsonGenerator jsonGenerator, SerializerProvider unused) 
      throws IOException, JsonProcessingException

class Foo
  public String bar;

  Foo(String bar)
  { = bar;

To suppress serializing Map entries with null keys, further custom serialization processing would be necessary.

Get current folder path

This works best for me, especially when using dotnet core single file publish. Path.GetDirectoryName(System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName).

Not unique table/alias

Your query contains columns which could be present with the same name in more than one table you are referencing, hence the not unique error. It's best if you make the references explicit and/or use table aliases when joining.


    SELECT pa.ProjectID, p.Project_Title, a.Account_ID, a.Username, a.Access_Type, c.First_Name, c.Last_Name
      FROM Project_Assigned pa
INNER JOIN Account a
        ON pa.AccountID = a.Account_ID
INNER JOIN Project p
        ON pa.ProjectID = p.Project_ID
INNER JOIN Clients c
        ON a.Account_ID = c.Account_ID
     WHERE a.Access_Type = 'Client';

How to send email from MySQL 5.1

If you have vps or dedicated server, You can code your own module using C programming.


 * File:   para.h
 * Author: rahul
 * Created on 10 February, 2016, 11:24 AM

#ifndef PARA_H
#define  PARA_H

#ifdef  __cplusplus
extern "C" {

#define From "<[email protected]>"
#define To "<[email protected]>" 
#define From_header "Rahul<[email protected]>"   
#define TO_header "Mini<[email protected]>"   
#define UID "smtp server account ID"
#define PWD "smtp server account PWD"
#define domain ""

#ifdef  __cplusplus

/* PARA_H */


 * File:   main.c
 * Author: rahul
 * Created on 10 February, 2016, 10:29 AM
#include <my_global.h>
#include <mysql.h>
#include <string.h>
#include <ctype.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <unistd.h>
#include "time.h"
#include "para.h"


my_bool SendEmail_init(UDF_INIT *initid,UDF_ARGS *arg,char *message);
void SendEmail_deinit(UDF_INIT *initid __attribute__((unused)));
char* SendEmail(UDF_INIT *initid, UDF_ARGS *arg,char *result,unsigned long *length, char *is_null,char* error);

 * base64
int Base64encode_len(int len);
int Base64encode(char * coded_dst, const char *plain_src,int len_plain_src);

int Base64decode_len(const char * coded_src);
int Base64decode(char * plain_dst, const char *coded_src);

/* aaaack but it's fast and const should make it shared text page. */
static const unsigned char pr2six[256] =
    /* ASCII table */
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
    64,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
    64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64

int Base64decode_len(const char *bufcoded)
    int nbytesdecoded;
    register const unsigned char *bufin;
    register int nprbytes;

    bufin = (const unsigned char *) bufcoded;
    while (pr2six[*(bufin++)] <= 63);

    nprbytes = (bufin - (const unsigned char *) bufcoded) - 1;
    nbytesdecoded = ((nprbytes + 3) / 4) * 3;

    return nbytesdecoded + 1;

int Base64decode(char *bufplain, const char *bufcoded)
    int nbytesdecoded;
    register const unsigned char *bufin;
    register unsigned char *bufout;
    register int nprbytes;

    bufin = (const unsigned char *) bufcoded;
    while (pr2six[*(bufin++)] <= 63);
    nprbytes = (bufin - (const unsigned char *) bufcoded) - 1;
    nbytesdecoded = ((nprbytes + 3) / 4) * 3;

    bufout = (unsigned char *) bufplain;
    bufin = (const unsigned char *) bufcoded;

    while (nprbytes > 4) {
    *(bufout++) =
        (unsigned char) (pr2six[*bufin] << 2 | pr2six[bufin[1]] >> 4);
    *(bufout++) =
        (unsigned char) (pr2six[bufin[1]] << 4 | pr2six[bufin[2]] >> 2);
    *(bufout++) =
        (unsigned char) (pr2six[bufin[2]] << 6 | pr2six[bufin[3]]);
    bufin += 4;
    nprbytes -= 4;

    /* Note: (nprbytes == 1) would be an error, so just ingore that case */
    if (nprbytes > 1) {
    *(bufout++) =
        (unsigned char) (pr2six[*bufin] << 2 | pr2six[bufin[1]] >> 4);
    if (nprbytes > 2) {
    *(bufout++) =
        (unsigned char) (pr2six[bufin[1]] << 4 | pr2six[bufin[2]] >> 2);
    if (nprbytes > 3) {
    *(bufout++) =
        (unsigned char) (pr2six[bufin[2]] << 6 | pr2six[bufin[3]]);

    *(bufout++) = '\0';
    nbytesdecoded -= (4 - nprbytes) & 3;
    return nbytesdecoded;

static const char basis_64[] =

int Base64encode_len(int len)
    return ((len + 2) / 3 * 4) + 1;

int Base64encode(char *encoded, const char *string, int len)
    int i;
    char *p;

    p = encoded;
    for (i = 0; i < len - 2; i += 3) {
    *p++ = basis_64[(string[i] >> 2) & 0x3F];
    *p++ = basis_64[((string[i] & 0x3) << 4) |
                    ((int) (string[i + 1] & 0xF0) >> 4)];
    *p++ = basis_64[((string[i + 1] & 0xF) << 2) |
                    ((int) (string[i + 2] & 0xC0) >> 6)];
    *p++ = basis_64[string[i + 2] & 0x3F];
    if (i < len) {
    *p++ = basis_64[(string[i] >> 2) & 0x3F];
    if (i == (len - 1)) {
        *p++ = basis_64[((string[i] & 0x3) << 4)];
        *p++ = '=';
    else {
        *p++ = basis_64[((string[i] & 0x3) << 4) |
                        ((int) (string[i + 1] & 0xF0) >> 4)];
        *p++ = basis_64[((string[i + 1] & 0xF) << 2)];
    *p++ = '=';

    *p++ = '\0';
    return p - encoded;

 end of base64

const char* GetIPAddress(const char* target_domain) {
    const char* target_ip;
    struct in_addr *host_address;
    struct hostent *raw_list = gethostbyname(target_domain);
    int i = 0;
    for (i; raw_list->h_addr_list[i] != 0; i++) {
        host_address = raw_list->h_addr_list[i];
        target_ip = inet_ntoa(*host_address);
    return target_ip;

char * MailHeader(const char* from, const char* to, const char* subject, const char* mime_type, const char* charset) {

    time_t now;
    char *app_brand = "Codevlog Test APP";
    char* mail_header = NULL;
    char date_buff[26];
    char Branding[6 + strlen(date_buff) + 2 + 10 + strlen(app_brand) + 1 + 1];
    char Sender[6 + strlen(from) + 1 + 1];
    char Recip[4 + strlen(to) + 1 + 1];
    char Subject[8 + 1 + strlen(subject) + 1 + 1];
    char mime_data[13 + 1 + 3 + 1 + 1 + 13 + 1 + strlen(mime_type) + 1 + 1 + 8 + strlen(charset) + 1 + 1 + 2];

    strftime(date_buff, (33), "%a , %d %b %Y %H:%M:%S", localtime(&now));

    sprintf(Branding, "DATE: %s\r\nX-Mailer: %s\r\n", date_buff, app_brand);
    sprintf(Sender, "FROM: %s\r\n", from);
    sprintf(Recip, "To: %s\r\n", to);
    sprintf(Subject, "Subject: %s\r\n", subject);
    sprintf(mime_data, "MIME-Version: 1.0\r\nContent-type: %s; charset=%s\r\n\r\n", mime_type, charset);

    int mail_header_length = strlen(Branding) + strlen(Sender) + strlen(Recip) + strlen(Subject) + strlen(mime_data) + 10;

    mail_header = (char*) malloc(mail_header_length);

    memcpy(&mail_header[0], &Branding, strlen(Branding));
    memcpy(&mail_header[0 + strlen(Branding)], &Sender, strlen(Sender));
    memcpy(&mail_header[0 + strlen(Branding) + strlen(Sender)], &Recip, strlen(Recip));
    memcpy(&mail_header[0 + strlen(Branding) + strlen(Sender) + strlen(Recip)], &Subject, strlen(Subject));
    memcpy(&mail_header[0 + strlen(Branding) + strlen(Sender) + strlen(Recip) + strlen(Subject)], &mime_data, strlen(mime_data));
    return mail_header;

my_bool SendEmail_init(UDF_INIT *initid,UDF_ARGS *arg,char *message){
     if (!(arg->arg_count == 2)) {
        strcpy(message, "Expected two arguments");
        return 1;

    arg->arg_type[0] = STRING_RESULT;// smtp server address
    arg->arg_type[1] = STRING_RESULT;// email body
    initid->ptr = (char*) malloc(2050 * sizeof (char));
    memset(initid->ptr, '\0', sizeof (initid->ptr));
    return 0;

void SendEmail_deinit(UDF_INIT *initid __attribute__((unused))){
    if (initid->ptr) {

char* SendEmail(UDF_INIT *initid, UDF_ARGS *arg,char *result,unsigned long *length, char *is_null,char* error){
   char *header = MailHeader(From_header, TO_header, "Hello Its a test Mail from Codevlog", "text/plain", "US-ASCII");
    int connected_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof (addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(25);
    if (inet_pton(AF_INET, GetIPAddress(arg->args[0]), &addr.sin_addr) == 1) {
        connect(connected_fd, (struct sockaddr*) &addr, sizeof (addr));
    if (connected_fd != -1) {
        int recvd = 0;
        const char recv_buff[4768];
        int sdsd;
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        char buff[1000];
        strcpy(buff, "EHLO "); //"EHLO\r\n"
        strcat(buff, domain);
        strcat(buff, "\r\n");
        send(connected_fd, buff, strlen(buff), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        char _cmd2[1000];
        strcpy(_cmd2, "AUTH LOGIN\r\n");
        int dfdf = send(connected_fd, _cmd2, strlen(_cmd2), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        char _cmd3[1000];
        Base64encode(&_cmd3, UID, strlen(UID));
        strcat(_cmd3, "\r\n");
        send(connected_fd, _cmd3, strlen(_cmd3), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        char _cmd4[1000];
        Base64encode(&_cmd4, PWD, strlen(PWD));
        strcat(_cmd4, "\r\n");
        send(connected_fd, _cmd4, strlen(_cmd4), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        char _cmd5[1000];
        strcpy(_cmd5, "MAIL FROM: ");
        strcat(_cmd5, From);
        strcat(_cmd5, "\r\n");
        send(connected_fd, _cmd5, strlen(_cmd5), 0);
        char skip[1000];
        sdsd = recv(connected_fd, skip, sizeof (skip), 0);

        char _cmd6[1000];
        strcpy(_cmd6, "RCPT TO: ");
        strcat(_cmd6, To); //
        strcat(_cmd6, "\r\n");
        send(connected_fd, _cmd6, strlen(_cmd6), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        char _cmd7[1000];
        strcpy(_cmd7, "DATA\r\n");
        send(connected_fd, _cmd7, strlen(_cmd7), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        send(connected_fd, header, strlen(header), 0);
        send(connected_fd, arg->args[1], strlen(arg->args[1]), 0);
        char _cmd9[1000];
        strcpy(_cmd9, "\r\n.\r\n.");
        send(connected_fd, _cmd9, sizeof (_cmd9), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);
        recvd += sdsd;

        char _cmd10[1000];
        strcpy(_cmd10, "QUIT\r\n");
        send(connected_fd, _cmd10, sizeof (_cmd10), 0);
        sdsd = recv(connected_fd, recv_buff + recvd, sizeof (recv_buff) - recvd, 0);

        memcpy(initid->ptr, recv_buff, strlen(recv_buff));
        *length = recvd;
    return initid->ptr;

To configure your project go through this video: (Send Email from MySQL on Linux) It will work for any mysql version (5.5, 5.6, 5.7)

I will resolve if any error appear in above code, Just Inform in comment

Resize background image in div using css


You have multiple options:

  1. background-size: 100% 100%; - image gets stretched (aspect ratio may be preserved, depending on browser)
  2. background-size: contain; - image is stretched without cutting it while preserving aspect ratio
  3. background-size: cover; - image is completely covering the element while preserving aspect ratio (image can be cut off)

/edit: And now, there is even more:

Demo on Codepen

Update 2017: Preview

Here are screenshots for some browsers to show their differences.


preview background types chrome


preview background types firefox


preview background types edge


preview background types ie11

Takeaway Message

background-size: 100% 100%; produces the least predictable result.


How to print a double with two decimals in Android?

use this one:

DecimalFormat form = new DecimalFormat("0.00");
etToll.setText(form.format(tvTotalAmount) );

Note: Data must be in decimal format (tvTotalAmount)

Unable to connect to SQL Server instance remotely

I know this is almost 1.5 years old, but I hope I can help someone with what I found.

I had built both a console app and a UWP app and my console connnected fine, but not my UWP. After hours of banging my head against the desk - if it's a intranet server hosting the SQL database you must enable "Private Networks (Client & Server)". It's under Package.appxmanifest and the Capabilities tab.Screenshot

Where do I find old versions of Android NDK?

The 64 bit versions are available also:

just replace the R8E release/version/iteration

anchor jumping by using javascript

Because when you do

window.location.href = "#"+anchor;

You load a new page, you can do:

<a href="#" onclick="jumpTo('one');">One</a>
<a href="#" id="one"></a>


    function getPosition(element){
        var e = document.getElementById(element);
        var left = 0;
        var top = 0;

            left += e.offsetLeft;
            top += e.offsetTop;
        }while(e = e.offsetParent);

        return [left, top];

    function jumpTo(id){    


How enable auto-format code for Intellij IDEA?

None of the solutions in Intellij is as elegant (or useful) as in Eclipse. What we need is feature request to the intellij so that we can add a hook (what actions to perform) when the IDE autosaves.

In Eclipse we can add "post-save" actions, such as organize imports and format the class. Yes you have to do a "save" or ctrl-s but the hook is very convenient.

What is AndroidX?

androidx will replace support library after 28.0.0. You should migrate your project to use it. androidx uses Semantic Versioning. Using AndroidX will not be confused by version that is presented in library name and package name. Life becomes easier

[AndroidX and support compatibility]

How to get a table creation script in MySQL Workbench?

  1. Open MySQL Workbench (6.3 CE)
  2. In "Navigator" select "Management"
  3. Then select "Data Export" (Here select the table whose create script you wish to export)
  4. In Drop down select "Dump Structure and Data"
  5. Select checkbox "Include Create Schema"
  6. Click the button "Start Export" Once export is complete it will display the location in which exported file is dumped in your system. Go to the location and open the exported file to find table creation script.

Or Check

JavaScript error: "is not a function"

For more generic advice on debugging this kind of problem MDN have a good article TypeError: "x" is not a function:

It was attempted to call a value like a function, but the value is not actually a function. Some code expects you to provide a function, but that didn't happen.

Maybe there is a typo in the function name? Maybe the object you are calling the method on does not have this function? For example, JavaScript objects have no map function, but JavaScript Array object do.

Basically the object (all functions in js are also objects) does not exist where you think it does. This could be for numerous reasons including(not an extensive list):

  • Missing script library
  • Typo
  • The function is within a scope that you currently do not have access to, e.g.:

var x = function(){_x000D_
   var y = function() {_x000D_
      alert('fired y');_x000D_
//the global scope can't access y because it is closed over in x and not exposed_x000D_
//y is not a function err triggered_x000D_

  • Your object/function does not have the function your calling:

var x = function(){_x000D_
   var y = function() {_x000D_
      alert('fired y');_x000D_
//z is not a function error (as above) triggered_x000D_

How to get the string size in bytes?

You can use strlen. Size is determined by the terminating null-character, so passed string should be valid.

If you want to get size of memory buffer, that contains your string, and you have pointer to it:

  • If it is dynamic array(created with malloc), it is impossible to get it size, since compiler doesn't know what pointer is pointing at. (check this)
  • If it is static array, you can use sizeof to get its size.

If you are confused about difference between dynamic and static arrays, check this.

Inserting code in this LaTeX document with indentation

Here is how to add inline code:

You can add inline code with {\tt code } or \texttt{ code }. If you want to format the inline code, then it would be best to make your own command


Also, note that code blocks can be loaded from other files with


breaklines isn't required, but I find it useful. Be aware that you'll have to specify \usepackage{ listings } for this one.

Update: The listings package also includes the \lstinline command, which has the same syntax highlighting features as the \lstlisting and \lstinputlisting commands (see Cloudanger's answer for configuration details). As mentioned in a few other answers, there's also the minted package, which provides the \mintinline command. Like \lstinline, \mintinline provides the same syntax highlighting as a regular minted code block:



  This is a sentence with \mintinline{python}{def inlineCode(a="ipsum)}

How to install easy_install in Python 2.7.1 on Windows 7

for 32-bit Python, the installer is here. after you run the installer, you will have easy_install.exe in your \Python27\Scripts directory

if you are looking for 64-bit installers, this is an excellent resource:

the author has installers for both Setuptools and Distribute. Either one will give you easy_install.exe

Reading a text file with SQL Server

if you want to read the file into a table at one time you should use BULK INSERT. ON the other hand if you preffer to parse the file line by line to make your own checks, you should take a look at this web: It is possible that you need to activate your xp_cmdshell or other OLE Automation features. Simple Google it and the script will appear. Hope to be useful.

Spring RestTemplate - how to enable full debugging/logging of requests/responses?

org.apache.http.wire give too unreadable logs, so I use logbook to log application Servlet and RestTemplate req/resp to log


compile group: 'org.zalando', name: 'logbook-spring-boot-starter', version: '1.13.0'


public class RestTemplateConfig {

private LogbookHttpRequestInterceptor logbookHttpRequestInterceptor;

private LogbookHttpResponseInterceptor logbookHttpResponseInterceptor;

public RestTemplate restTemplate() {
    return new RestTemplateBuilder()
        .requestFactory(new MyRequestFactorySupplier())

class MyRequestFactorySupplier implements Supplier<ClientHttpRequestFactory> {

    public ClientHttpRequestFactory get() {
        // Using Apache HTTP client.
        CloseableHttpClient client = HttpClientBuilder.create()
        HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(client);
        return clientHttpRequestFactory;


HTTP response header content disposition for attachments

Try the Content-Disposition header

Content-Disposition: attachment; filename=<file name.ext> 

How to programmatically empty browser cache?

On Chrome, you should be able to do this using the benchmarking extension. You need to start your chrome with the following switches:

./chrome --enable-benchmarking --enable-net-benchmarking 

In Chrome's console now you can do the following:


As you can tell from above commands, it not only clears the browser cache, but also clears the DNS cache and closes network connections. These are great when you're doing page load time benchmarking. Obviously you don't have to use them all if not needed (e.g. clearCache() should suffice if you need to clear the cache only and don't care about DNS cache and connections).

How to check if a char is equal to an empty space?

In this case, you are thinking of the String comparing function "String".equals("some_text"). Chars do not need to use this function. Instead a standard == comparison operator will suffice.

private static int countNumChars(String s) {
    for(char c : s.toCharArray()){
        if (c == ' ') // your resulting outcome

Restrict varchar() column to specific values?

When you are editing a table
Right Click -> Check Constraints -> Add -> Type something like Frequency IN ('Daily', 'Weekly', 'Monthly', 'Yearly') in expression field and a good constraint name in (Name) field.
You are done.

How do I expire a PHP session after 30 minutes?

How PHP handles sessions is quite confusing for beginners to understand. This might help them by giving an overview of how sessions work: how sessions work(custom-session-handlers)

How to pass an object into a state using UI-router?

In version 0.2.13, You should be able to pass objects into $state.go,

$state.go('myState', {myParam: {some: 'thing'}})

$stateProvider.state('myState', {
                url: '/myState/{myParam:json}',
                params: {myParam: null}, ...

and then access the parameter in your controller.

$stateParams.myParam //should be {some: 'thing'}

myParam will not show up in the URL.


See the comment by christopherthielen, reproduced here for convenience:

christopherthielen: Yes, this should be working now in 0.2.13.

.state('foo', { url: '/foo/:param1?param2', params: { param3: null } // null is the default value });

$state.go('foo', { param1: 'bar', param2: 'baz', param3: { id: 35, name: 'what' } });

$stateParams in 'foo' is now { param1: 'bar', param2: 'baz', param3: { id: 35, name: 'what' } }

url is /foo/bar?param2=baz.

python requests file upload

In Ubuntu you can apply this way,

to save file at some location (temporary) and then open and send it to API

      path ='static/tmp/' +, ContentFile(
      path12 = os.path.join(os.getcwd(), "static/tmp/" +
      data={} #can be anything u want to pass along with File
      file1 = open(path12, 'rb')
      header = {"Content-Disposition": "attachment; filename=" +, "Authorization": "JWT " + token}

Limit length of characters in a regular expression?


This expression takes the number of length 2,4 and 5. Valid Inputs are 12 1234 12345

How to pass Multiple Parameters from ajax call to MVC Controller

  type: "POST",
  contentType: "application/json; charset=utf-8",
  url: "ChnagePassword.aspx/AutocompleteSuggestions",
  data: "{'searchstring':'" + request.term + "','st':'Arb'}",
  dataType: "json",
  success: function (data) {
     response($.map(data.d, function (item) {
         return { value: item }
  error: function (result) {

Static constant string (class member)

You have to define your static member outside the class definition and provide the initializer there.


// In a header file (if it is in a header file in your case)
class A {   
  static const string RECTANGLE;

and then

// In one of the implementation files
const string A::RECTANGLE = "rectangle";

The syntax you were originally trying to use (initializer inside class definition) is only allowed with integral and enum types.

Starting from C++17 you have another option, which is quite similar to your original declaration: inline variables

// In a header file (if it is in a header file in your case)
class A {   
  inline static const string RECTANGLE = "rectangle";

No additional definition is needed.

Starting from C++20 instead of const you can declare it constexpr in this variant. Explicit inline would no longer be necessary, since constexpr implies inline.

Edit Crystal report file without Crystal Report software

My dad moved his office after 30 year and they need to update the address in the header of their Crystal Reports 7 (1997!) based billing system.

After buying old copies of Access 97 and Visual Studio 2003 Pro, I found out that both programs were too new - they could open the RPT files, but they saved them with an updated version that would not open in the billing system.

I ended up being able to make the changes using this life-saver program...

It was available with a 10 day free trial, and I only needed about 10 minutes to make my changes. That said, I would have happily paid whatever they asked for it. :)

Some hints:

  1. When I opened my RPT files, I got an error saving the database could not be found. I ignored this error and everything worked fine.
  2. Because my RPT files were Crystal Reports version 7, I had to go into Options->Misc and tell the program to save in the old format...

enter image description here

How do you use $sce.trustAsHtml(string) to replicate ng-bind-html-unsafe in Angular 1.2+


$scope.get_pre = function(x) {
    return $sce.trustAsHtml(x);


<pre ng-bind-html="get_pre(html)"></pre>

Return Type for jdbcTemplate.queryForList(sql, object, classType)

A complete solution for JdbcTemplate, NamedParameterJdbcTemplate with or without RowMapper Example.

// Create a Employee table

create table employee(  
id number(10),  
name varchar2(100),  
salary number(10)  

======================================================================= //

public class Employee {
private int id;  
private String name;  
private float salary;  

//no-arg and parameterized constructors  

public Employee(){};

public Employee(int  id, String name, float salary){;;

//getters and setters  
public int getId() {
    return id;
public void setId(int id) { = id;
public String getName() {
    return name;
public void setName(String name) { = name;
public float getSalary() {
    return salary;
public void setSalary(float salary) {
    this.salary = salary;
public String toString(){  
   return id+" "+name+" "+salary;  


========================================================================= //

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;

public class EmployeeDao {  
  private JdbcTemplate jdbcTemplate;  
  private NamedParameterJdbcTemplate nameTemplate;  

  public void setnameTemplate(NamedParameterJdbcTemplate template) {  
    this.nameTemplate = template;  

 public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {  
  this.jdbcTemplate = jdbcTemplate;  

 // BY using JdbcTemplate
 public int saveEmployee(Employee e){  
 int id = e.getId();
 String name = e.getName();
 float salary = e.getSalary();
 Object p[] = {id, name, salary};
    String query="insert into employee values(?,?,?)";
      return jdbcTemplate.update(query, p);
    /*String query="insert into employee     values('"+e.getId()+"','"+e.getName()+"','"+e.getSalary()+"')"; 
      return jdbcTemplate.update(query);


//By using NameParameterTemplate
public void insertEmploye(Employee e) {  
String query="insert into employee values (:id,:name,:salary)";  
Map<String,Object> map=new HashMap<String,Object>();  

nameTemplate.execute(query,map,new MyPreparedStatement());

// Updating Employee
public int updateEmployee(Employee e){  
String query="update employee set  name='"+e.getName()+"',salary='"+e.getSalary()+"' where id='"+e.getId()+"' ";  
  return jdbcTemplate.update(query);  
 // Deleting a Employee row
 public int deleteEmployee(Employee e){  
 String query="delete from employee where id='"+e.getId()+"' ";  
 return jdbcTemplate.update(query);  
 //Selecting Single row with condition and also all rows
    public int selectEmployee(Employee e){  
     //String query="select * from employee where id='"+e.getId()+"' ";
      String query="select * from employee";
      List<Map<String, Object>> rows = jdbcTemplate.queryForList(query);
       for(Map<String, Object> row : rows){
          String id = row.get("id").toString();
          String name = (String)row.get("name");
          String salary = row.get("salary").toString();
          System.out.println(id + " " + name + " " + salary );

      return 1;

   // Can use MyrowMapper class an implementation class for RowMapper interface
    public void getAllEmployee()

    String query="select * from employee";
    List<Employee> l = jdbcTemplate.query(query, new MyrowMapper());

    Iterator it=l.iterator();
      Employee e=(Employee);
      System.out.println(e.getId()+" "+e.getName()+" "+e.getSalary());

  //Can use directly a RowMapper implementation class without an object creation
  public List<Employee> getAllEmployee1(){
    return jdbcTemplate.query("select * from employee",new RowMapper<Employee>(){  
      public Employee mapRow(ResultSet rs, int rownumber) throws  SQLException    {  
            Employee e=new Employee();  
            return e;  
     // End of all the function


================================================================ //

 import java.sql.ResultSet;
 import java.sql.SQLException;
 import org.springframework.jdbc.core.RowMapper;

 public class MyrowMapper implements RowMapper<Employee> {

  public Employee mapRow(ResultSet rs, int rownumber) throws SQLException 
    Employee e=new Employee();  
     return e;  

========================================================== //

import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.PreparedStatementCallback;

 public class MyPreparedStatement implements  PreparedStatementCallback<Object> {

 public Object doInPreparedStatement(PreparedStatement ps)
        throws SQLException, DataAccessException {

     return ps.executeUpdate(); 


===================================================================== //

import java.util.List;
import org.springframework.context.ApplicationContext;

public class Test {  

public static void main(String[] args) {  
 ApplicationContext ctx=new     ClassPathXmlApplicationContext("applicationContext.xml");  

 EmployeeDao dao=(EmployeeDao)ctx.getBean("edao"); 

  // By calling constructor for insert
    int status=dao.saveEmployee(new Employee(103,"Ajay",35000));  
 // By calling PreparedStatement
  dao.insertEmploye(new Employee(103,"Roh",25000));

 // By calling setter-getter for update
    Employee e=new Employee(); 
    int status=dao.updateEmployee(e);
 // By calling constructor for update
    int status=dao.updateEmployee(new Employee(102,"Sadhan",15000)); 
 // Deleting a record 
    Employee e=new Employee(); 
    int status=dao.deleteEmployee(e); 
 // Selecting single or all rows
    Employee e=new Employee(); 
    int status=dao.selectEmployee(e);
// Can use MyrowMapper class an implementation class for RowMapper interface


// Can use directly a RowMapper implementation class without an object creation
    List<Employee> list=dao.getAllEmployee1();  
    for(Employee e1:list)  


================================================================== //applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>  

<bean id="ds"        class="org.springframework.jdbc.datasource.DriverManagerDataSource">  
 <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />  
 <property name="url" value="jdbc:oracle:thin:@localhost:1521:xe" />  
 <property name="username" value="hr" />  
 <property name="password" value="hr" />  

 <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">  
 <property name="dataSource" ref="ds"></property>  

<bean id="nameTemplate"   
<constructor-arg ref="ds"></constructor-arg>  

<bean id="edao" class="EmployeeDao"> 
<!-- Can use both --> 
<property name="nameTemplate" ref="nameTemplate"></property>
<property name="jdbcTemplate" ref="jdbcTemplate"></property> 


How to add element in Python to the end of list using list.insert?

list.insert with any index >= len(of_the_list) places the value at the end of list. It behaves like append

Python 3.7.4
>>>lst.insert(len(lst), 101)
[10, 20, 30, 101]
>>>lst.insert(len(lst)+50, 202)
[10, 20, 30, 101, 202]

Time complexity, append O(1), insert O(n)

Using jQuery to see if a div has a child with a certain class

Simple Way

if ($('#text-field > p.filled-text').length != 0)

Bypass invalid SSL certificate errors when calling web services in .Net

For newbies, you can extend your partial service class in a separate cs file and add the code the code provided by "imanabidi" to get it integrated

Jquery If radio button is checked

if($('#test2').is(':checked')) {

Opening database file from within SQLite command-line shell

create different db files using
      >sqlite3 test1.db
sqlite> create table test1 (name text);
sqlite> insert into test1 values('sourav');
      >sqlite3 test2.db
sqlite> create table test2 (eid integer);
sqlite> insert into test2 values (6);
SQLite version 3.8.5 2014-06-04 14:06:34
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
sqlite> .open test1.db
sqlite> select * from test1;
sqlite> .open test2.db
sqlite> select * from test1;
Error: no such table: test1
sqlite> select * from test2;
sqlite> .exit

Thank YOU.

How to set image for bar button with swift?

Swift 4.

@IBOutlet weak var settingBarBtn: UIBarButtonItem! {
    didSet {
        let imageSetting = UIImageView(image: UIImage(named: "settings"))
        imageSetting.image = imageSetting.image!.withRenderingMode(.alwaysOriginal)
        imageSetting.tintColor = UIColor.clear
        settingBarBtn.image = imageSetting.image

How to get JSON response from http.Get

The results from json.Unmarshal (into var data interface{}) do not directly match your Go type and variable declarations. For example,

package main

import (

type Tracks struct {
    Toptracks []Toptracks_info

type Toptracks_info struct {
    Track []Track_info
    Attr  []Attr_info

type Track_info struct {
    Name       string
    Duration   string
    Listeners  string
    Mbid       string
    Url        string
    Streamable []Streamable_info
    Artist     []Artist_info
    Attr       []Track_attr_info

type Attr_info struct {
    Country    string
    Page       string
    PerPage    string
    TotalPages string
    Total      string

type Streamable_info struct {
    Text      string
    Fulltrack string

type Artist_info struct {
    Name string
    Mbid string
    Url  string

type Track_attr_info struct {
    Rank string

func get_content() {
    // json data
    url := ""
    url += "&limit=1" // limit data for testing
    res, err := http.Get(url)
    if err != nil {
    body, err := ioutil.ReadAll(res.Body)
    if err != nil {
    var data interface{} // TopTracks
    err = json.Unmarshal(body, &data)
    if err != nil {
    fmt.Printf("Results: %v\n", data)

func main() {


Results: map[toptracks:map[track:map[name:Get Lucky (feat. Pharrell Williams) listeners:1863 url: artist:map[name:Daft Punk mbid:056e4f3e-d505-4dad-8ec1-d04f521cbb56 url:] image:[map[#text: size:small] map[#text: size:medium] map[#text: size:large] map[#text: size:extralarge]] @attr:map[rank:1] duration:369 mbid: streamable:map[#text:1 fulltrack:0]] @attr:map[country:Netherlands page:1 perPage:1 totalPages:500 total:500]]]

Connect Java to a MySQL database

You can see all steps to connect MySQL database from Java application here. For other database, you just need to change the driver in first step only. Please make sure that you provide right path to database and correct username and password.


Matplotlib color according to class labels

A simple solution is to assign color for each class. This way, we can control how each color is for each class. For example:

arr1 = [1, 2, 3, 4, 5]
arr2 = [2, 3, 3, 4, 4]
labl = [0, 1, 1, 0, 0]
color= ['red' if l == 0 else 'green' for l in labl]
plt.scatter(arr1, arr2, color=color)

R: numeric 'envir' arg not of length one in predict()

There are several problems here:

  1. The newdata argument of predict() needs a predictor variable. You should thus pass it values for Coupon, instead of Total, which is the response variable in your model.

  2. The predictor variable needs to be passed in as a named column in a data frame, so that predict() knows what the numbers its been handed represent. (The need for this becomes clear when you consider more complicated models, having more than one predictor variable).

  3. For this to work, your original call should pass df in through the data argument, rather than using it directly in your formula. (This way, the name of the column in newdata will be able to match the name on the RHS of the formula).

With those changes incorporated, this will work:

model <- lm(Total ~ Coupon, data=df)
new <- data.frame(Coupon = df$Coupon)
predict(model, newdata = new, interval="confidence")

There are No resources that can be added or removed from the server

I used mvn eclipse:eclipse -Dwtpversion=2.0 in command line in the folder where I had my pom.xml. Then I refreshed the project in eclipse IDE. After that I was able to add my project.

Can a java lambda have more than 1 parameter?

Some lambda function :

import org.junit.Test;
import java.awt.event.ActionListener;
import java.util.function.Function;

public class TestLambda {

public void testLambda() {

    System.out.println("test some lambda function");

    //1-any input | any output:
    //lambda define:
    Runnable lambda1 = () -> System.out.println("no parameter");
    //lambda execute:;

    //2-one input(as ActionEvent) | any output:
    //lambda define:
    ActionListener lambda2 = (p) -> System.out.println("One parameter as action");
    //lambda execute:

    //3-one input | by output(as Integer):
    //lambda define:
    Function<String, Integer> lambda3 = (p1) -> {
        System.out.println("one parameters: " + p1);
        return 10;
    //lambda execute:

    //4-two input | any output
    //lambda define:
    TwoParameterFunctionWithoutReturn<String, Integer> lambda4 = (p1, p2) -> {
        System.out.println("two parameters: " + p1 + ", " + p2);
    //lambda execute:
    lambda4.apply("param1", 10);

    //5-two input | by output(as Integer)
    //lambda define:
    TwoParameterFunctionByReturn<Integer, Integer> lambda5 = (p1, p2) -> {
        System.out.println("two parameters: " + p1 + ", " + p2);
        return p1 + p2;
    //lambda execute:
    lambda5.apply(10, 20);

    //6-three input(Integer,Integer,String) | by output(as Integer)
    //lambda define:
    ThreeParameterFunctionByReturn<Integer, Integer, Integer> lambda6 = (p1, p2, p3) -> {
        System.out.println("three parameters: " + p1 + ", " + p2 + ", " + p3);
        return p1 + p2 + p3;
    //lambda execute:
    lambda6.apply(10, 20, 30);


public interface TwoParameterFunctionWithoutReturn<T, U> {
    public void apply(T t, U u);

public interface TwoParameterFunctionByReturn<T, U> {
    public T apply(T t, U u);

public interface ThreeParameterFunctionByReturn<M, N, O> {
    public Integer apply(M m, N n, O o);

Javascript reduce on array of objects

To formalize what has been pointed out, a reducer is a catamorphism which takes two arguments which may be the same type by coincidence, and returns a type which matches the first argument.

function reducer (accumulator: X, currentValue: Y): X { }

That means that the body of the reducer needs to be about converting currentValue and the current value of the accumulator to the value of the new accumulator.

This works in a straightforward way, when adding, because the accumulator and the element values both happen to be the same type (but serve different purposes).

[1, 2, 3].reduce((x, y) => x + y);

This just works because they're all numbers.

[{ age: 5 }, { age: 2 }, { age: 8 }]
  .reduce((total, thing) => total + thing.age, 0);

Now we're giving a starting value to the aggregator. The starting value should be the type that you expect the aggregator to be (the type you expect to come out as the final value), in the vast majority of cases. While you aren't forced to do this (and shouldn't be), it's important to keep in mind.

Once you know that, you can write meaningful reductions for other n:1 relationship problems.

Removing repeated words:

const skipIfAlreadyFound = (words, word) => words.includes(word)
    ? words
    : words.concat(word);

const deduplicatedWords = aBunchOfWords.reduce(skipIfAlreadyFound, []);

Providing a count of all words found:

const incrementWordCount = (counts, word) => {
  counts[word] = (counts[word] || 0) + 1;
  return counts;
const wordCounts = words.reduce(incrementWordCount, { });

Reducing an array of arrays, to a single flat array:

const concat = (a, b) => a.concat(b);

const numbers = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9]
].reduce(concat, []);

Any time you're looking to go from an array of things, to a single value that doesn't match a 1:1, reduce is something you might consider.

In fact, map and filter can both be implemented as reductions:

const map = (transform, array) =>
  array.reduce((list, el) => list.concat(transform(el)), []);

const filter = (predicate, array) => array.reduce(
  (list, el) => predicate(el) ? list.concat(el) : list,

I hope this provides some further context for how to use reduce.

The one addition to this, which I haven't broken into yet, is when there is an expectation that the input and output types are specifically meant to be dynamic, because the array elements are functions:

const compose = (...fns) => x =>
  fns.reduceRight((x, f) => f(x), x);

const hgfx = h(g(f(x)));
const hgf = compose(h, g, f);
const hgfy = hgf(y);
const hgfz = hgf(z);

Changing MongoDB data store directory

I found a special case that causes symlinks to appear to fail:

I did a standard enterprise install of mongodb but changed the /var/lib/mongodb to a symlink as I wanted to use an XFS filesystem for my database folder and a third filesystem for the log folder.

$sudo systemctl start mongod (fails with a message no permission to write to mongodb.log).. but it succceded if I started with the same configuration file:

.. as the owner of the external drives (ziggy) I was able to start $mongod --config /etc/mongodb.conf --fork

I eventually discovered that .. the symlinks pointed to a different filesystem and the mongodb (user) did not have permission to browse the folder that the symlink referred. Both the symlinks and the folders the symlinks referred had expansive rights to the mongod user so it made no sense?

/var/log/mongodb was changed (from the std ent install) to a symlink AND I had checked before:

$ ll /var/log/mongodb lrwxrwxrwx 1 mongodb mongodb 38 Oct 28 21:58 /var/log/mongodb -> /media/ziggy/XFS_DB/mongodb/log/

$ ll -d /media/ziggy/Ext4DataBase/mongodb/log drwxrwxrwx 2 mongodb mongodb 4096 Nov 1 12:05 /media/ashley/XFS_DB/mongodb/log/

.. But so it seemed to make no sense.. of course user mongodb had rwx access to the link, the folder and to the file mongodb.log .. but it couldnt find it via the symlink because the BASE folder of the media couldnt be searched by mongodb.

SO.. I EVENTUALLY DID THIS: $ ll /media/ziggy/ . . drwx------ 5 ziggy ziggy 4096 Oct 28 21:49 XFS_DB/

and found the offending missing x permissions..

$chmod a+x /media/ziggy/XFS_DB solved the problem

Seems stupid in hindsight but no searches turned up anything useful.

How to place and center text in an SVG rectangle

Full Detail Blog :

<svg width="600" height="600">_x000D_
  <!--   Circle -->_x000D_
  <g transform="translate(50,40)">_x000D_
    <circle cx="0" cy="0" r="35" stroke="#aaa" stroke-width="2" fill="#fff"></circle>_x000D_
    <text x="0" y="0" alignment-baseline="middle" font-size="12" stroke-width="0" stroke="#000" text-anchor="middle">HueLink</text>_x000D_
  <!--   In Rectangle text position needs to be given half of width and height of rectangle respectively -->_x000D_
  <!--   Rectangle -->_x000D_
  <g transform="translate(150,20)">_x000D_
    <rect width="150" height="40" stroke="#aaa" stroke-width="2" fill="#fff"></rect>_x000D_
    <text x="75" y="20" alignment-baseline="middle" font-size="12" stroke-width="0" stroke="#000" text-anchor="middle">HueLink</text>_x000D_
  <!--   Rectangle -->_x000D_
  <g transform="translate(120,140)">_x000D_
    <ellipse cx="0" cy="0" rx="100" ry="50" stroke="#aaa" stroke-width="2" fill="#fff"></ellipse>_x000D_
    <text x="0" y="0" alignment-baseline="middle" font-size="12" stroke-width="0" stroke="#000" text-anchor="middle">HueLink</text>_x000D_

How to find the parent element using javascript

Use the change event of the select:

   $(this).parents('td').css('background', '#000000');

LINQ to Entities how to update a record

Just modify one of the returned entities:

Customer c = (from x in dataBase.Customers
             where x.Name == "Test"
             select x).First();
c.Name = "New Name";

Note, you can only update an entity (something that extends EntityObject, not something that you have projected using something like select new CustomObject{Name = x.Name}

How can one see the structure of a table in SQLite?

.schema TableName

Where TableName is the name of the Table

Difference between jQuery’s .hide() and setting CSS to display: none

To use both is a nice answer; it's not a question of either or.

The advantage of using both is that the CSS will hide the element immediately when the page loads. The jQuery .hide will flash the element for a quarter of a second then hide it.

In the case when we want to have the element not shown when the page loads we can use CSS and set display:none & use the jQuery .hide(). If we plan to toggle the element we can use jQuery toggle.

On a CSS hover event, can I change another div's styling?

This can not be done purely with css. This is a behaviour, which affects the styling of the page.

With jquery you can quickly implement the behavior from your question:

$(function() {
  $('#a').hover(function() {
    $('#b').css('background-color', 'yellow');
  }, function() {
    // on mouseout, reset the background colour
    $('#b').css('background-color', '');

How do I make a dotted/dashed line in Android?

For a Dotted effect on a Canvas, set this attribute to the paint object :

paint.setPathEffect(new DashPathEffect(new float[] {0,30}, 0));

And change the value 30 as your render suits you : it represents the "distance" between each dots.

enter image description here

AWS Lambda import module error in python

There are just so many gotchas when creating deployment packages for AWS Lambda (for Python). I have spent hours and hours on debugging sessions until I found a formula that rarely fails.

I have created a script that automates the entire process and therefore makes it less error prone. I have also wrote tutorial that explains how everything works. You may want to check it out:

Hassle-Free Python Lambda Deployment [Tutorial + Script]

How to convert flat raw disk image to vmdk for virtualbox or vmplayer?

Just to give you an another option, you could use as well. dd2vmdk is a *nix-based program that allows you to mount raw disk images (created by dd, dcfldd, dc3dd, ftk imager, etc) by taking the raw image, analyzing the master boot record (physical sector 0), and getting specific information that is need to create a vmdk file.

Personally, imo Qemu and the Zapotek's raw2vmdk tools are the best overall options to convert dd to vmdks.

Disclosure: I am the author of this project.

How to add RSA key to authorized_keys file?

Make sure when executing Michael Krelin's solution you do the following

cat <your_public_key_file> >> ~/.ssh/authorized_keys

Note the double > without the double > the existing contents of authorized_keys will be over-written (nuked!) and that may not be desirable

Get random sample from list while maintaining ordering of items?

random.sample implement it.

>>> random.sample([1, 2, 3, 4, 5],  3)   # Three samples without replacement
[4, 1, 5]

How to take backup of a single table in a MySQL database?

just use mysqldump -u root database table or if using with password mysqldump -u root -p pass database table

Save and load weights in keras

For loading weights, you need to have a model first. It must be:


If you want to save and load the entire model (this includes the model's configuration, it's weights and the optimizer states for further training):

model = load_model('filename')

finding and replacing elements in a list

a = [1,2,3,4,5,1,2,3,4,5,1,12]
for i in range (len(a)):
    if a[i]==2:

You can use a for and or while loop; however if u know the builtin Enumerate function, then it is recommended to use Enumerate.1

Setting a backgroundImage With React Inline Styles

If you are using ES5 -

backgroundImage: "url(" + Background + ")"

If you are using ES6 -

backgroundImage: `url(${Background})`

Basically removing unnecessary curly braces while adding value to backgroundImage property works will work.

jQuery ajax post file field

File uploads can not be done this way, no matter how you break it down. If you want to do an ajax/async upload, I would suggest looking into something like Uploadify, or Valums

Flask at first run: Do not use the development server in a production environment

If for some people (like me earlier) the above answers don't work, I think the following answer would work (for Mac users I think) Enter the following commands to do flask run

$ export FLASK_APP =
$ export FLASK_ENV = development
$ flask run

Alternatively you can do the following (I haven't tried this but one resource online talks about it)

$ export FLASK_APP =
$ python -m flask run

source: For more

Do I commit the package-lock.json file created by npm 5?

Yes, package-lock.json is intended to be checked into source control. If you're using npm 5+, you may see this notice on the command line: created a lockfile as package-lock.json. You should commit this file. According to npm help package-lock.json:

package-lock.json is automatically generated for any operations where npm modifies either the node_modules tree, or package.json. It describes the exact tree that was generated, such that subsequent installs are able to generate identical trees, regardless of intermediate dependency updates.

This file is intended to be committed into source repositories, and serves various purposes:

  • Describe a single representation of a dependency tree such that teammates, deployments, and continuous integration are guaranteed to install exactly the same dependencies.

  • Provide a facility for users to "time-travel" to previous states of node_modules without having to commit the directory itself.

  • To facilitate greater visibility of tree changes through readable source control diffs.

  • And optimize the installation process by allowing npm to skip repeated metadata resolutions for previously-installed packages.

One key detail about package-lock.json is that it cannot be published, and it will be ignored if found in any place other than the toplevel package. It shares a format with npm-shrinkwrap.json, which is essentially the same file, but allows publication. This is not recommended unless deploying a CLI tool or otherwise using the publication process for producing production packages.

If both package-lock.json and npm-shrinkwrap.json are present in the root of a package, package-lock.json will be completely ignored.

Remove last character from string. Swift language

Swift 4:

let choppedString = String(theString.dropLast())

In Swift 2, do this:

let choppedString = String(theString.characters.dropLast())

I recommend this link to get an understanding of Swift strings.

"application blocked by security settings" prevent applets running using oracle SE 7 update 51 on firefox on Linux mint

As an alternative answer, there's a command line to invoke directly the Control Panel, which is javaws -viewer, should work for both openJDK and Oracle's JDK (thanks @Nasser for checking the availability in Oracle's JDK)

Same caution to run as the user you need to access permissions with applies.

Oracle find a constraint

select * from all_constraints
where owner = '<NAME>'
and constraint_name = 'SYS_C00381400'

Like all data dictionary views, this a USER_CONSTRAINTS view if you just want to check your current schema and a DBA_CONSTRAINTS view for administration users.

The construction of the constraint name indicates a system generated constraint name. For instance, if we specify NOT NULL in a table declaration. Or indeed a primary or unique key. For example:

SQL> create table t23 (id number not null primary key)
  2  /

Table created.

SQL> select constraint_name, constraint_type
  2  from user_constraints
  3  where table_name = 'T23'
  4  /

CONSTRAINT_NAME                C
------------------------------ -
SYS_C00935190                  C
SYS_C00935191                  P


'C' for check, 'P' for primary.

Generally it's a good idea to give relational constraints an explicit name. For instance, if the database creates an index for the primary key (which it will do if that column is not already indexed) it will use the constraint name oo name the index. You don't want a database full of indexes named like SYS_C00935191.

To be honest most people don't bother naming NOT NULL constraints.

Select Specific Columns from Spark DataFrame

Just by using select select you can select particular columns, give them readable names and cast them. For example like this:
          .where('_c2.isNotNull && '_c3.isNotNull && '_c2 =!= 0.0 && '_c3 =!= 0.0)

Centering the pagination in bootstrap

You can add your custom Css:

    margin:0 auto;

Thank you

How can I programmatically determine if my app is running in the iphone simulator?

The previous answers are a little dated. I found that all you need to do is query the TARGET_IPHONE_SIMULATOR macro (no need to include any other header files [assuming you are coding for iOS]).

I attempted TARGET_OS_IPHONE but it returned the same value (1) when running on an actual device and simulator, that's why I recommend using TARGET_IPHONE_SIMULATOR instead.

Cannot serve WCF services in IIS on Windows 8

You can also achieve this by Turning windows feature ON. enter image description here enter image description here

Programmatically scroll a UIScrollView

scrollView.setContentOffset(CGPoint(x: y, y: x), animated: true)

How to call a web service from jQuery


The OP was not looking to use cross-domain requests, but jQuery supports JSONP as of v1.5. See jQuery.ajax(), specificically the crossDomain parameter.

The regular jQuery Ajax requests will not work cross-site, so if you want to query a remote RESTful web service, you'll probably have to make a proxy on your server and query that with a jQuery get request. See this site for an example.

If it's a SOAP web service, you may want to try the jqSOAPClient plugin.

Can functions be passed as parameters?

Here is the sample "Map" implementation in Go. Hope this helps!!

func square(num int) int {
    return num * num

func mapper(f func(int) int, alist []int) []int {
    var a = make([]int, len(alist), len(alist))
    for index, val := range alist {

        a[index] = f(val)
    return a

func main() {
    alist := []int{4, 5, 6, 7}
    result := mapper(square, alist)


How to execute the start script with Nodemon

I know it's 5 years late, if you want to use nodemon.json you may try this,

  "verbose": true,
  "ignore": ["*.test.js", "fixtures/*"],
  "execMap": {
    "js": "electron ." // 'js' is for the extension, and 'electron .' is command that I want to execute

The execMap will execute like a script in package.json, then you can run nodemon js

How to execute an oracle stored procedure?

Oracle 10g Express Edition ships with Oracle Application Express (Apex) built-in. You're running this in its SQL Commands window, which doesn't support SQL*Plus syntax.

That doesn't matter, because (as you have discovered) the BEGIN...END syntax does work in Apex.

Convert boolean to int in Java

boolean b = ....; 
int i = -("false".indexOf("" + b));

Arrays in type script

A cleaner way to do this:

class Book {
    public Title: string;
    public Price: number;
    public Description: string;

    constructor(public BookId: number, public Author: string){}


var bks: Book[] = [
    new Book(1, "vamsee")

Where can I find Android source code online?

I've found a way to get only the Contacts application:

git clone

which is good enough for me for now, but doesn't answer the question of browsing the code on the web.

Can you use @Autowired with static fields?

You can use ApplicationContextAware

public class AppContext implements ApplicationContextAware{
    public static ApplicationContext applicationContext;

    public AppBeans(){

    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;


static ABean bean = AppContext.applicationContext.getBean("aBean",ABean.class);

Render Partial View Using jQuery in ASP.NET MVC

Using standard Ajax call to achieve same result

            url: '@Url.Action("_SearchStudents")?NationalId=' + $('#NationalId').val(),
            type: 'GET',
            error: function (xhr) {
                alert('Error: ' + xhr.statusText);

            success: function (result) {


public ActionResult _SearchStudents(string NationalId)


            return PartialView("_SearchStudents", model);

DLL References in Visual C++

You need to do a couple of things to use the library:

  1. Make sure that you have both the *.lib and the *.dll from the library you want to use. If you don't have the *.lib, skip #2

  2. Put a reference to the *.lib in the project. Right click the project name in the Solution Explorer and then select Configuration Properties->Linker->Input and put the name of the lib in the Additional Dependencies property.

  3. You have to make sure that VS can find the lib you just added so you have to go to the Tools menu and select Options... Then under Projects and Solutions select VC++ Directories,edit Library Directory option. From within here you can set the directory that contains your new lib by selecting the 'Library Files' in the 'Show Directories For:' drop down box. Just add the path to your lib file in the list of directories. If you dont have a lib you can omit this, but while your here you will also need to set the directory which contains your header files as well under the 'Include Files'. Do it the same way you added the lib.

After doing this you should be good to go and can use your library. If you dont have a lib file you can still use the dll by importing it yourself. During your applications startup you can explicitly load the dll by calling LoadLibrary (see: for more info)



Remember to use #include < Foo.h > as opposed to #include "foo.h". The former searches the include path. The latter uses the local project files.

How do I assert equality on two classes without an equals method?

You can use Apache commons lang ReflectionToStringBuilder

You can either specify the attributes you want to test one by one, or better, exclude those you don't want:

String s = new ReflectionToStringBuilder(o, ToStringStyle.SHORT_PREFIX_STYLE)
                .setExcludeFieldNames(new String[] { "foo", "bar" }).toString()

You then compare the two strings as normal. For the point about reflection being slow, I assume this is only for testing, so shouldn't be so important.

Count lines in large files

If your data resides on HDFS, perhaps the fastest approach is to use hadoop streaming. Apache Pig's COUNT UDF, operates on a bag, and therefore uses a single reducer to compute the number of rows. Instead you can manually set the number of reducers in a simple hadoop streaming script as follows:

$HADOOP_HOME/bin/hadoop jar $HADOOP_HOME/hadoop-streaming.jar -Dmapred.reduce.tasks=100 -input <input_path> -output <output_path> -mapper /bin/cat -reducer "wc -l"

Note that I manually set the number of reducers to 100, but you can tune this parameter. Once the map-reduce job is done, the result from each reducer is stored in a separate file. The final count of rows is the sum of numbers returned by all reducers. you can get the final count of rows as follows:

$HADOOP_HOME/bin/hadoop fs -cat <output_path>/* | paste -sd+ | bc

What is a good regular expression to match a URL?

I was trying to put together some JavaScript to validate a domain name (ex. and if it validates enable a submit button. I thought that I would share my code for those who are looking to accomplish something similar. It expects a domain without any http:// or www. value. The script uses a stripped down regular expression from above for domain matching, which isn't strict about fake TLD.

$(function () {
  $('#whitelist_add').keyup(function () {
    if ($(this).val() == '') { //Check to see if there is any text entered
        //If there is no text within the input, disable the button
        $('.whitelistCheck').attr('disabled', 'disabled');
    } else {
        // Domain name regular expression
        var regex = new RegExp("^([0-9A-Za-z-\\.@:%_\+~#=]+)+((\\.[a-zA-Z]{2,3})+)(/(.)*)?(\\?(.)*)?");
        if (regex.test($(this).val())) {
            // Domain looks OK
            //alert("Successful match");
        } else {
            // Domain is NOT OK
            //alert("No match");
            $('.whitelistCheck').attr('disabled', 'disabled');


<form action="domain_management.php" method="get">
    <input type="text" name="whitelist_add" id="whitelist_add" placeholder="">
    <button type="submit" class="btn btn-success whitelistCheck" disabled='disabled'>Add to Whitelist</button>

Spacing between elements

In general we use margins on one of the elements, not spacer elements.

how to compare the Java Byte[] array?

You can also use org.apache.commons.lang.ArrayUtils.isEquals()

java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonFactory

Add the following dependency to your pom.xml


Creating columns in listView and add items

Your first problem is that you are passing -3 to the 2nd parameter of Columns.Add. It needs to be -2 for it to auto-size the column. Source: (look at the comments on the code example at the bottom)

private void initListView()
    // Add columns
    lvRegAnimals.Columns.Add("Id", -2,HorizontalAlignment.Left);
    lvRegAnimals.Columns.Add("Name", -2, HorizontalAlignment.Left);
    lvRegAnimals.Columns.Add("Age", -2, HorizontalAlignment.Left);

You can also use the other overload, Add(string). E.g:


Reference for more overloads:

Second, to add items to the ListView, you need to create instances of ListViewItem and add them to the listView's Items collection. You will need to use the string[] constructor.

var item1 = new ListViewItem(new[] {"id123", "Tom", "24"});
var item2 = new ListViewItem(new[] {person.Id, person.Name, person.Age});

You can also store objects in the item's Tag property.

item2.Tag = person;

And then you can extract it

var person = item2.Tag as Person;

Let me know if you have any questions and I hope this helps!

how to get current location in google map android

Your current location might not be available immediately, after the map fragment is initialized.

After set


you have to wait until you see the blue dot shown on your MapView. Then

Location myLocation = googleMap.getMyLocation();

myLocation won't be null.

I think you better use the LocationClient instead, and implement your own LocationListener.onLocationChanged(Location l)

Receiving Location Updates will show you how to get current location from LocationClient

How to force deletion of a python object?

  1. Add an exit handler that closes all the bars.
  2. __del__() gets called when the number of references to an object hits 0 while the VM is still running. This may be caused by the GC.
  3. If __init__() raises an exception then the object is assumed to be incomplete and __del__() won't be invoked.

Pushing to Git returning Error Code 403 fatal: HTTP request failed

After changing https to http within gitbox app, it worked for me.

ApiNotActivatedMapError for simple html page using google-places-api

Assuming you already have a application created under google developer console, Follow the below steps

  1. Go to the following link you will be getting the below page enter image description here
  2. Click on ENABLE APIS AND SERVICES you will be directed to following page enter image description here
  3. Select the desired option - in this case "Maps JavaScript API"
  4. Click ENABLE button as below, enter image description here

Note: Please use a server to load the html file

Random record from MongoDB

Now you can use the aggregate. Example:

   [ { $sample: { size: 3 } } ]

See the doc.

Transparent CSS background color

yes, thats possible. just use the rgba-syntax for your background-color.

  background-color: rgba(255, 0, 0, 0.5); //semi-transparent red

'' is not recognized as an internal or external command, operable program or batch file

When you want to run an executable file from the Command prompt, (cmd.exe), or a batch file, it will:

  • Search the current working directory for the executable file.
  • Search all locations specified in the %PATH% environment variable for the executable file.

If the file isn't found in either of those options you will need to either:

  1. Specify the location of your executable.
  2. Change the working directory to that which holds the executable.
  3. Add the location to %PATH% by apending it, (recommended only with extreme caution).

You can see which locations are specified in %PATH% from the Command prompt, Echo %Path%.

Because of your reported error we can assume that Mobile.exe is not in the current directory or in a location specified within the %Path% variable, so you need to use 1., 2. or 3..

Examples for 1.



"C:\directory path with spaces\My-App\Mobile.exe"

Alternatively you may try:

Start C:\directory_path_without_spaces\My-App\Mobile.exe


Start "" "C:\directory path with spaces\My-App\Mobile.exe"

Where "" is an empty title, (you can optionally add a string between those doublequotes).

Examples for 2.

CD /D C:\directory_path_without_spaces\My-App


CD /D "C:\directory path with spaces\My-App"

You could also use the /D option with Start to change the working directory for the executable to be run by the start command

Start /D C:\directory_path_without_spaces\My-App Mobile.exe


Start "" /D "C:\directory path with spaces\My-App" Mobile.exe

Counting the number of elements in array

This expands on the answer by Denis Bubnov.

I used this to find child values of array elements—namely if there was a anchor field in paragraphs on a Drupal 8 site to build a table of contents.

{% set count = 0 %}
{% for anchor in items %}
    {% if anchor.content['#paragraph'].field_anchor_link.0.value %}
        {% set count = count + 1 %}
    {% endif %}
{% endfor %}

{% if count > 0 %}
 ---  build the toc here --
{% endif %}

Init method in Spring Controller (annotation version)

public class InitHelloWorld implements BeanPostProcessor {

   public Object postProcessBeforeInitialization(Object bean,
             String beanName) throws BeansException {
       System.out.println("BeforeInitialization : " + beanName);
       return bean;  // you can return any other object as well

   public Object postProcessAfterInitialization(Object bean,
             String beanName) throws BeansException {
       System.out.println("AfterInitialization : " + beanName);
       return bean;  // you can return any other object as well


How to read a large file line by line?

From the python documentation for fileinput.input():

This iterates over the lines of all files listed in sys.argv[1:], defaulting to sys.stdin if the list is empty

further, the definition of the function is:

fileinput.FileInput([files[, inplace[, backup[, mode[, openhook]]]]])

reading between the lines, this tells me that files can be a list so you could have something like:

for each_line in fileinput.input([input_file, input_file]):

See here for more information

Create an array or List of all dates between two dates

I know this is an old post but try using an extension method:

    public static IEnumerable<DateTime> Range(this DateTime startDate, DateTime endDate)
        return Enumerable.Range(0, (endDate - startDate).Days + 1).Select(d => startDate.AddDays(d));

and use it like this

    var dates = new DateTime(2000, 1, 1).Range(new DateTime(2000, 1, 31));

Feel free to choose your own dates, you don't have to restrict yourself to January 2000.

Populate one dropdown based on selection in another

Could you please have a look at:

Basically, the data is stored in an Array and the options are added accordingly. I think the code says more than a thousand words.

var data = [ // The data
    ['ten', [
    ['twenty', [
        'twentyone', 'twentytwo'

$a = $('#a'); // The dropdowns
$b = $('#b');

for(var i = 0; i < data.length; i++) {
    var first = data[i][0];
    $a.append($("<option>"). // Add options
       data("sel", i).

$a.change(function() {
    var index = $(this).children('option:selected').data('sel');
    var second = data[index][1]; // The second-choice data

    $b.html(''); // Clear existing options in second dropdown

    for(var j = 0; j < second.length; j++) {
        $b.append($("<option>"). // Add options
           data("sel", j).
}).change(); // Trigger once to add options at load of first choice

How to upload folders on GitHub

I've just gone through that process again. Always end up cloning the repo locally, upload the folder I want to have in that repo to that cloned location, commit the changes and then push it.

Note that if you're dealing with large files, you'll need to consider using something like Git LFS.

apache mod_rewrite is not working or not enabled

Please try

sudo a2enmod rewrite

or use correct apache restart command

sudo /etc/init.d/apache2 restart 

Ansible: copy a directory content to another directory

The simplest solution I've found to copy the contents of a folder without copying the folder itself is to use the following:

- name: Move directory contents
  command: cp -r /<source_path>/. /<dest_path>/

This resolves @surfer190's follow-up question:

Hmmm what if you want to copy the entire contents? I noticed that * doesn't work – surfer190 Jul 23 '16 at 7:29

* is a shell glob, in that it relies on your shell to enumerate all the files within the folder before running cp, while the . directly instructs cp to get the directory contents (see

single line comment in HTML

TL;DR For conforming browsers, yes; but there are no conforming browsers, so no.

According to the HTML 4 specification, <!------> hello--> is a perfectly valid comment. However, I've not found a browser which implements this correctly (i.e. per the specification) due to developers not knowing, nor following, the standards (as digitaldreamer pointed out).

You can find the definition of a comment for HTML4 on the w3c's website:

Another thing that many browsers get wrong is that -- > closes a comment just like -->.

CreateProcess error=2, The system cannot find the file specified

The complete first argument of exec is being interpreted as the executable. Use

p = rt.exec(new String[] {"winrar.exe", "x", "h:\\myjar.jar", "*.*", "h:\\new" }

Regular expression "^[a-zA-Z]" or "[^a-zA-Z]"

There is a difference.

When the ^ character appears outside of [] matches the beginning of the line (or string). When the ^ character appears inside the [], it matches any character not appearing inside the [].

Using Python 3 in virtualenv

virtualenv --python=/usr/bin/python3 <name of env>

worked for me.

Setting mime type for excel document

For .xls use the following content-type


For Excel 2007 version and above .xlsx files format


What is this date format? 2011-08-12T20:17:46.384Z

@John-Skeet gave me the clue to fix my own issue around this. As a younger programmer this small issue is easy to miss and hard to diagnose. So Im sharing it in the hopes it will help someone.

My issue was that I wanted to parse the following string contraining a time stamp from a JSON I have no influence over and put it in more useful variables. But I kept getting errors.

So given the following (pay attention to the string parameter inside ofPattern();

String str = "20190927T182730.000Z"

LocalDateTime fin;
fin = LocalDateTime.parse( str, DateTimeFormatter.ofPattern("yyyyMMdd'T'HHmmss.SSSZ") );


Exception in thread "main" java.time.format.DateTimeParseException: Text 
'20190927T182730.000Z' could not be parsed at index 19

The problem? The Z at the end of the Pattern needs to be wrapped in 'Z' just like the 'T' is. Change "yyyyMMdd'T'HHmmss.SSSZ" to "yyyyMMdd'T'HHmmss.SSS'Z'" and it works.

Removing the Z from the pattern alltogether also led to errors.

Frankly, I'd expect a Java class to have anticipated this.

How can I get date and time formats based on Culture Info?

You could take a look at the DateTimeFormat property which contains the culture specific formats.

What is the (best) way to manage permissions for Docker shared volumes?

If you using Docker Compose, start the container in previleged mode:

    image: wordpress:4.5.3
    restart: always
      - 8084:80
    privileged: true

Create ul and li elements in javascript.

Try out below code snippet:

 var list = [];
 var text;

function update() {

    for (var i = 0; i < list.length; i++) {
       console.log( i );
       var letters;
       var ul = document.getElementById("list");
       var li = document.createElement("li");


       letters += "<li>"  + list[i] + "</li>";

 document.getElementById("list").innerHTML = letters;


function myFunction() {
    text = prompt("enter TODO");  

SQL WHERE ID IN (id1, id2, ..., idn)

I think you mean SqlServer but on Oracle you have a hard limit how many IN elements you can specify: 1000.

What is the difference between single-quoted and double-quoted strings in PHP?

In PHP, both 'my name' and "my name" are string. You can read more about it at the PHP manual.

Thing you should know are

$a = 'name';
$b = "my $a"; == 'my name'
$c = 'my $a'; != 'my name'

In PHP, people use single quote to define a constant string, like 'a', 'my name', 'abc xyz', while using double quote to define a string contain identifier like "a $b $c $d".

And other thing is,

echo 'my name';

is faster than

echo "my name";


echo 'my ' . $a;

is slower than

echo "my $a";

This is true for other used of string.

javascript password generator

Here is a function provides you more options to set min of special chars, min of upper chars, min of lower chars and min of number

function randomPassword(len = 8, minUpper = 0, minLower = 0, minNumber = -1, minSpecial = -1) {
    let chars = String.fromCharCode(...Array(127).keys()).slice(33),//chars
        A2Z = String.fromCharCode(...Array(91).keys()).slice(65),//A-Z
        a2z = String.fromCharCode(...Array(123).keys()).slice(97),//a-z
        zero2nine = String.fromCharCode(...Array(58).keys()).slice(48),//0-9
        specials = chars.replace(/\w/g, '')
    if (minSpecial < 0) chars = zero2nine + A2Z + a2z
    if (minNumber < 0) chars = chars.replace(zero2nine, '')
    let minRequired = minSpecial + minUpper + minLower + minNumber
    let rs = [].concat(
        Array.from({length: minSpecial ? minSpecial : 0}, () => specials[Math.floor(Math.random() * specials.length)]),
        Array.from({length: minUpper ? minUpper : 0}, () => A2Z[Math.floor(Math.random() * A2Z.length)]),
        Array.from({length: minLower ? minLower : 0}, () => a2z[Math.floor(Math.random() * a2z.length)]),
        Array.from({length: minNumber ? minNumber : 0}, () => zero2nine[Math.floor(Math.random() * zero2nine.length)]),
        Array.from({length: Math.max(len, minRequired) - (minRequired ? minRequired : 0)}, () => chars[Math.floor(Math.random() * chars.length)]),
    return rs.sort(() => Math.random() > Math.random()).join('')
randomPassword(12, 1, 1, -1, -1)// -> DDYxdVcvIyLgeB
randomPassword(12, 1, 1, 1, -1)// -> KYXTbKf9vpMu0
randomPassword(12, 1, 1, 1, 1)// -> hj|9)V5YKb=7

Using a scanner to accept String input and storing in a String Array

There is no use of pointers in java so far. You can create an object from the class and use different classes which are linked with each other and use the functions of every class in main class.

Pyspark: Filter dataframe based on multiple conditions

You can also write like below (without pyspark.sql.functions):

df.filter('d<5 and (col1 <> col3 or (col1 = col3 and col2 <> col4))').show()


|col1|col2|col3|col4|  d|
|   A|  xx|   D|  vv|  4|
|   A|   x|   A|  xx|  3|
|   E| xxx|   B|  vv|  3|
|   F|xxxx|   F| vvv|  4|
|   G| xxx|   G|  xx|  4|

How to have click event ONLY fire on parent DIV, not children?

$(".advanced ul li").live('click',function(e){
    if( != this) return;
    // this code will execute only when you click to li and not to a child

Import Python Script Into Another?

It's worth mentioning that (at least in python 3), in order for this to work, you must have a file named in the same directory.

printing a value of a variable in postgresql

You can raise a notice in Postgres as follows:

raise notice 'Value: %', deletedContactId;

Read here

How do I define a method in Razor?

You can simply declare them as local functions in a razor block (i.e. @{}).

    int Add(int x, int y)
        return x + y;

<div class="container">
        @Add(2, 5)

How to get input field value using PHP

Use PHP's $_POST or $_GET superglobals to retrieve the value of the input tag via the name of the HTML tag.

For Example, change the method in your form and then echo out the value by the name of the input:

Using $_GET method:

<form name="form" action="" method="get">
  <input type="text" name="subject" id="subject" value="Car Loan">

To show the value:

<?php echo $_GET['subject']; ?>

Using $_POST method:

<form name="form" action="" method="post">
  <input type="text" name="subject" id="subject" value="Car Loan">

To show the value:

<?php echo $_POST['subject']; ?>

What is considered a good response time for a dynamic, personalized web application?

Of course, it lays in the nature of your question, so answers are highly subjective.

The first response of a website is also only a small part of the time until a page is readable/usable.

I am annoyed by everything larger than 10 sec responses. I think a website should be rendered after 5-7 sec.

Btw: has an excellent response time!

Include CSS,javascript file in Yii Framework

Do somthing like this by adding these line to your view files;


Remove part of string after "."

You could do:

sub("*\\.[0-9]", "", a)


str_sub(a, start=1, end=-3)

Loop inside React JSX

I've found one more solution to follow the map render:


And a separate function:

getcontent() {
    const bodyarea = => (
        <tr key={movies._id}>
                    onClick={this.deletMovie.bind(this, movies._id)}
                    className="btn btn-danger"
    return bodyarea;

This example solves many problems easily.

Using Tkinter in python to edit the title bar

For anybody who runs into the issue of having two windows open, and runs across this question. Here is how I stumbled upon a solution.

The reason the code in this question is producing two windows is because

Frame.__init__(self, parent)

is being run before

self.root = Tk()

The simple fix is to run Tk() before running Frame.__init_()

self.root = Tk()
Frame.__init__(self, parent)

Why that is the case, I'm not entirely sure.

git switch branch without discarding local changes

  • git stash to save your uncommited changes
  • git stash list to list your saved uncommited stashes
  • git stash apply stash@{x} where x can be 0,1, of stashes that you have made

Regex to get NUMBER only from String

Either [0-9] or \d1 should suffice if you only need a single digit. Append + if you need more.

1 The semantics are slightly different as \d potentially matches any decimal digit in any script out there that uses decimal digits.

Scrolling to element using webdriver?

You can scroll to the element by using javascript through the execute_javascript method. For example here is how I do it using SeleniumLibrary on Robot Framework:

web_element = self.selib.find_element(locator)
    'arguments[0].scrollIntoView({behavior: "instant", block: "start", inline: "start"});'

Adding devices to team provisioning profile

I faced multiple time the same issue that I add device info to portal so I can publish build to fabric testing but device is still missing due to how Xcode is not updating team provisioning profile.

So based on other answers and my own experience, the best and quickest way is to remove all Provisioning profiles manually by command line while automatic signing will download them again with updated devices.

If this can lead to some unknown issues I don't know and highly doubt, but it works for me just fine.

So just:

cd ~/Library/MobileDevice/Provisioning\ Profiles/
rm *

And try again...

How to declare a type as nullable in TypeScript?

Nullable type can invoke runtime error. So I think it's good to use a compiler option --strictNullChecks and declare number | null as type. also in case of nested function, although input type is null, compiler can not know what it could break, so I recommend use !(exclamination mark).

function broken(name: string | null): string {
  function postfix(epithet: string) {
    return name.charAt(0) + '.  the ' + epithet; // error, 'name' is possibly null
  name = name || "Bob";
  return postfix("great");

function fixed(name: string | null): string {
  function postfix(epithet: string) {
    return name!.charAt(0) + '.  the ' + epithet; // ok
  name = name || "Bob";
  return postfix("great");


What algorithm for a tic-tac-toe game can I use to determine the "best move" for the AI?

A typical algo for tic-tac-toe should look like this:

Board : A nine-element vector representing the board. We store 2 (indicating Blank), 3 (indicating X), or 5 (indicating O). Turn: An integer indicating which move of the game about to be played. The 1st move will be indicated by 1, last by 9.

The Algorithm

The main algorithm uses three functions.

Make2: returns 5 if the center square of the board is blank i.e. if board[5]=2. Otherwise, this function returns any non-corner square (2, 4, 6 or 8).

Posswin(p): Returns 0 if player p can’t win on his next move; otherwise, it returns the number of the square that constitutes a winning move. This function will enable the program both to win and to block opponents win. This function operates by checking each of the rows, columns, and diagonals. By multiplying the values of each square together for an entire row (or column or diagonal), the possibility of a win can be checked. If the product is 18 (3 x 3 x 2), then X can win. If the product is 50 (5 x 5 x 2), then O can win. If a winning row (column or diagonal) is found, the blank square in it can be determined and the number of that square is returned by this function.

Go (n): makes a move in square n. this procedure sets board [n] to 3 if Turn is odd, or 5 if Turn is even. It also increments turn by one.

The algorithm has a built-in strategy for each move. It makes the odd numbered move if it plays X, the even-numbered move if it plays O.

Turn = 1    Go(1)   (upper left corner).
Turn = 2    If Board[5] is blank, Go(5), else Go(1).
Turn = 3    If Board[9] is blank, Go(9), else Go(3).
Turn = 4    If Posswin(X) is not 0, then Go(Posswin(X)) i.e. [ block opponent’s win], else Go(Make2).
Turn = 5    if Posswin(X) is not 0 then Go(Posswin(X)) [i.e. win], else if Posswin(O) is not 0, then Go(Posswin(O)) [i.e. block win], else if Board[7] is blank, then Go(7), else Go(3). [to explore other possibility if there be any ].
Turn = 6    If Posswin(O) is not 0 then Go(Posswin(O)), else if Posswin(X) is not 0, then Go(Posswin(X)), else Go(Make2).
Turn = 7    If Posswin(X) is not 0 then Go(Posswin(X)), else if Posswin(X) is not 0, then Go(Posswin(O)) else go anywhere that is blank.
Turn = 8    if Posswin(O) is not 0 then Go(Posswin(O)), else if Posswin(X) is not 0, then Go(Posswin(X)), else go anywhere that is blank.
Turn = 9    Same as Turn=7.

I have used it. Let me know how you guys feel.

How can I call a method in Objective-C?

[self score]; instead of @selector(score)

window.onload vs $(document).ready()

The document.ready event occurs when the HTML document has been loaded, and the window.onload event occurs always later, when all content (images, etc) has been loaded.

You can use the document.ready event if you want to intervene "early" in the rendering process, without waiting for the images to load. If you need the images (or any other "content") ready before your script "does something", you need to wait until window.onload.

For instance, if you are implementing a "Slide Show" pattern, and you need to perform calculations based on image sizes, you may want to wait until window.onload. Otherwise, you might experience some random problems, depending on how fast the images will get loaded. Your script would be running concurrently with the thread that loads images. If your script is long enough, or the server is fast enough, you may not notice a problem, if images happen to arrive in time. But the safest practice would be allowing for images to get loaded.

document.ready could be a nice event for you to show some "loading..." sign to users, and upon window.onload, you can complete any scripting that needed resources loaded, and then finally remove the "Loading..." sign.

Examples :-

// document ready events
     alert("document is ready..");

// using JQuery
   alert("document is ready..");

// window on load event
function myFunction(){
  alert("window is loaded..");
window.onload = myFunction;

Get array elements from index to end

The [:-1] removes the last element. Instead of




You can read up on Python slicing notation here: Explain Python's slice notation

NumPy slicing is an extension of that. The NumPy tutorial has some coverage: Indexing, Slicing and Iterating.

Best implementation for Key Value Pair Data Structure?

Use something like this:

class Tree < T > : Dictionary < T, IList< Tree < T > > >  

It's ugly, but I think it will give you what you want. Too bad KeyValuePair is sealed.

Import multiple csv files into pandas and concatenate into one DataFrame

import os

os.system("awk '(NR == 1) || (FNR > 1)' file*.csv > merged.csv")

Where NR and FNR represent the number of the line being processed.

FNR is the current line within each file.

NR == 1 includes the first line of the first file (the header), while (FNR > 1) skips the first line of each subsequent file.

How can I enable "URL Rewrite" Module in IIS 8.5 in Server 2012?

Thought I'd give a full answer combining some of the possible intricacies required for completeness.

  1. Check if you have 32-bit or 64-bit IIS installed:
    • Go to IIS Manager ? Application Pools, choose the appropriate app pool then Advanced Settings.
    • Check the setting "Enable 32-bit Applications". If that's true, that means the worker process is forced to run in 32-bit. If the setting is false, then the app pool is running in 64-bit mode.
    • You can also open up Task Manager and check w3wp.exe. If it's showing as w3wp*32.exe then it's 32-bit.
  2. Download the appropriate version here:
  3. Install it.
  4. Close and reopen IIS Manager to ensure the URL Rewrite module appears.

How to convert characters to HTML entities using plain JavaScript

Best solution is posted at implementation of PHP function htmlentities

The format is htmlentities(string, quote_style, charset, double_encode) Full documentation on the PHP function which is identical can be read here

set gvim font in .vimrc file

I am trying to set this in .vimrc file like below

For GUI specific settings use the .gvimrc instead of .vimrc, which on Windows is either $HOME\_gvimrc or $VIM\_gvimrc.

Check the :help .gvimrc for details. In essence, on start-up VIM reads the .vimrc. After that, if GUI is activated, it also reads the .gvimrc. IOW, all VIM general settings should be kept in .vimrc, all GUI specific things in .gvimrc. (But if you do no use console VIM then you can simply forget about the .vimrc.)

set guifont=Consolas\ 10

The syntax is wrong. After :set guifont=* you can always check the proper syntax for the font using :set guifont?. VIM Windows syntax is :set guifont=Consolas:h10. I do not see precise specification for that, though it is mentioned in the :help win32-faq.

In android how to set navigation drawer header image and name programmatically in class file?

  nav = ( NavigationView ) findViewById( );

    if( nav != null ){
        LinearLayout mParent = ( LinearLayout ) nav.getHeaderView( 0 );

        if( mParent != null ){
            // Set your values to the image and text view by declaring and setting as you need to here.

            SharedPreferences prefs = getSharedPreferences("user_data", MODE_PRIVATE);
            String photoUrl = prefs.getString("photo_url", null);
            String user_name = prefs.getString("name", "User");

            if(photoUrl!=null) {
                Log.e("Photo Url: ", photoUrl);

                TextView userName = mParent.findViewById(;

                ImageView user_imageView = mParent.findViewById(;

                RequestOptions requestOptions = new RequestOptions();




Hope this helps.

How do I pre-populate a jQuery Datepicker textbox with today's date?

In order to set the datepicker to a certain default time (the current date in my case) on loading, AND then have the option to choose another date the syntax is :

    $(function() { 
        // initialize the datapicker

        // set the time
        var currentDate = new Date();

    //  set the options for the button  
            dateFormat: 'dd/mm',
            showOn: "button",
          // whatever option Or event you want 

axios post request to send form data

i needed to calculate the content length aswell

const formHeaders = form.getHeaders();
formHeaders["Content-Length"] = form.getLengthSync()

const config = {headers: formHeaders}

return, form, config)
.then(res => {
    console.log(`form uploaded`)

How to determine an object's class?

Multiple right answers were presented, but there are still more methods: Class.isAssignableFrom() and simply attempting to cast the object (which might throw a ClassCastException).

Possible ways summarized

Let's summarize the possible ways to test if an object obj is an instance of type C:

// Method #1
if (obj instanceof C)

// Method #2
if (C.class.isInstance(obj))

// Method #3
if (C.class.isAssignableFrom(obj.getClass()))

// Method #4
try {
    C c = (C) obj;
    // No exception: obj is of type C or IT MIGHT BE NULL!
} catch (ClassCastException e) {

// Method #5
try {
    C c = C.class.cast(obj);
    // No exception: obj is of type C or IT MIGHT BE NULL!
} catch (ClassCastException e) {

Differences in null handling

There is a difference in null handling though:

  • In the first 2 methods expressions evaluate to false if obj is null (null is not instance of anything).
  • The 3rd method would throw a NullPointerException obviously.
  • The 4th and 5th methods on the contrary accept null because null can be cast to any type!

To remember: null is not an instance of any type but it can be cast to any type.


  • Class.getName() should not be used to perform an "is-instance-of" test becase if the object is not of type C but a subclass of it, it may have a completely different name and package (therefore class names will obviously not match) but it is still of type C.
  • For the same inheritance reason Class.isAssignableFrom() is not symmetric:
    obj.getClass().isAssignableFrom(C.class) would return false if the type of obj is a subclass of C.

Android App Not Install. An existing package by the same name with a conflicting signature is already installed

The problem is the keys that have been used to sign the APKs, by default if you are running directly from your IDE and opening your Emulator, the APK installed in the Emulator is signed with your debug-key(usually installed in ~/.android/debug.keystore), so if the previous APK was signed with a different key other than the one you are currently using you will always get the signatures conflict, in order to fix it, make sure you are using the very same key to sign both APKs, even if the previous APK was signed with a debug-key from another SDK, the keys will definitely be different.

Also if you don't know exactly what key was used before to sign the apk and yet you want to install the new version of your app, you can just uninstall the previous application and reinstall the new one.

Hope this Helps...


What is the difference between `sorted(list)` vs `list.sort()`?

sorted() returns a new sorted list, leaving the original list unaffected. list.sort() sorts the list in-place, mutating the list indices, and returns None (like all in-place operations).

sorted() works on any iterable, not just lists. Strings, tuples, dictionaries (you'll get the keys), generators, etc., returning a list containing all elements, sorted.

  • Use list.sort() when you want to mutate the list, sorted() when you want a new sorted object back. Use sorted() when you want to sort something that is an iterable, not a list yet.

  • For lists, list.sort() is faster than sorted() because it doesn't have to create a copy. For any other iterable, you have no choice.

  • No, you cannot retrieve the original positions. Once you called list.sort() the original order is gone.

Retrieving a List from a in Java 8

In case someone (like me) out there is looking for ways deal with Objects instead of primitive types then use mapToObj()

String ss = "An alternative way is to insert the following VM option before "
        + "the -vmargs option in the Eclipse shortcut properties(edit the "
        + "field Target inside the Shortcut tab):";

List<Character> ll = ss
                        .mapToObj(c -> new Character((char) c))

System.out.println("List type: " + ll.getClass());
System.out.println("Elem type: " + ll.get(0).getClass());;


List type: class java.util.ArrayList
Elem type: class java.lang.Character
An alternative way is to insert the following VM o

Disabling enter key for form

You can try something like this, if you use jQuery.

$("form").bind("keydown", function(e) {
   if (e.keyCode === 13) return false;

That will wait for a keydown, if it is Enter, it will do nothing.

How to format number of decimal places in wpf using style/template?

The accepted answer does not show 0 in integer place on giving input like 0.299. It shows .3 in WPF UI. So my suggestion to use following string format

<TextBox Text="{Binding Value,  StringFormat={}{0:#,0.0}}" 

How can I properly handle 404 in ASP.NET MVC?

I really like cottsaks solution and think its very clearly explained. my only addition was to alter step 2 as follows

public abstract class MyController : Controller

    #region Http404 handling

    protected override void HandleUnknownAction(string actionName)
        //if controller is ErrorController dont 'nest' exceptions
        if(this.GetType() != typeof(ErrorController))

    public ActionResult InvokeHttp404(HttpContextBase httpContext)
        IController errorController = ObjectFactory.GetInstance<ErrorController>();
        var errorRoute = new RouteData();
        errorRoute.Values.Add("controller", "Error");
        errorRoute.Values.Add("action", "Http404");
        errorRoute.Values.Add("url", httpContext.Request.Url.OriginalString);
        errorController.Execute(new RequestContext(
             httpContext, errorRoute));

        return new EmptyResult();


Basically this stops urls containing invalid actions AND controllers from triggering the exception routine twice. eg for urls such as asdfsdf/dfgdfgd

Distinct() with lambda?

IEnumerable<Customer> filteredList = originalList
  .GroupBy(customer => customer.CustomerId)
  .Select(group => group.First());

Socket accept - "Too many open files"

Similar issue on Ubuntu 18 on vsphere. The cause - Config file nginx.conf contains too many log files and sockets. Sockets are treated as files in Linux. When nginx -s reload or sudo service nginx start/restart, the Too many open files error appeared in error.log.

NGINX worker processes were launched by NGINX user. Ulimit (soft and hard) for nginx user was 65536. The ulimit and setting limits.conf did not work.

The rlimit setting in nginx.conf did not help either: worker_rlimit_nofile 65536;

The solution that worked was:

$ mkdir -p /etc/systemd/system/nginx.service.d
$ nano /etc/systemd/system/nginx.service.d/nginx.conf
$ systemctl daemon-reload
$ systemctl restart nginx.service

What does localhost:8080 mean?

http: //localhost:8080/web


  • localhost ( hostname ) is the machine name or IP address of the host server e.g Glassfish, Tomcat.
  • 8080 ( port ) is the address of the port on which the host server is listening for requests.

http ://localhost/web


  • localhost ( hostname ) is the machine name or IP address of the host server e.g Glassfish, Tomcat.
  • host server listening to default port 80.

How can I create directories recursively?

I agree with Cat Plus Plus's answer. However, if you know this will only be used on Unix-like OSes, you can use external calls to the shell commands mkdir, chmod, and chown. Make sure to pass extra flags to recursively affect directories:

>>> import subprocess
>>> subprocess.check_output(['mkdir', '-p', 'first/second/third']) 
# Equivalent to running 'mkdir -p first/second/third' in a shell (which creates
# parent directories if they do not yet exist).

>>> subprocess.check_output(['chown', '-R', 'dail:users', 'first'])
# Recursively change owner to 'dail' and group to 'users' for 'first' and all of
# its subdirectories.

>>> subprocess.check_output(['chmod', '-R', 'g+w', 'first'])
# Add group write permissions to 'first' and all of its subdirectories.

EDIT I originally used commands, which was a bad choice since it is deprecated and vulnerable to injection attacks. (For example, if a user gave input to create a directory called first/;rm -rf --no-preserve-root /;, one could potentially delete all directories).

EDIT 2 If you are using Python less than 2.7, use check_call instead of check_output. See the subprocess documentation for details.

How to list all functions in a Python module?

If you want to get the list of all the functions defined in the current file, you can do it that way:

# Get this script's name.
import os
script_name = os.path.basename(__file__).rstrip(".py")

# Import it from its path so that you can use it as a Python object.
import importlib.util
spec = importlib.util.spec_from_file_location(script_name, __file__)
x = importlib.util.module_from_spec(spec)

# List the functions defined in it.
from inspect import getmembers, isfunction
list_of_functions = getmembers(x, isfunction)

As an application example, I use that for calling all the functions defined in my unit testing scripts.

This is a combination of codes adapted from the answers of Thomas Wouters and adrian here, and from Sebastian Rittau on a different question.

SQL Server IN vs. EXISTS Performance

EXISTS will be faster because once the engine has found a hit, it will quit looking as the condition has proved true.

With IN, it will collect all the results from the sub-query before further processing.

Image UriSource and Data Binding

You can also simply set the Source attribute rather than using the child elements. To do this your class needs to return the image as a Bitmap Image. Here is an example of one way I've done it

<Image Width="90" Height="90" 
       Source="{Binding Path=ImageSource}"
       Margin="0,0,0,5" />

And the class property is simply this

public object ImageSource {
    get {
        BitmapImage image = new BitmapImage();

        try {
            image.CacheOption = BitmapCacheOption.OnLoad;
            image.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
            image.UriSource = new Uri( FullPath, UriKind.Absolute );
            return DependencyProperty.UnsetValue;

        return image;

I suppose it may be a little more work than the value converter, but it is another option.

Linux: is there a read or recv from socket with timeout?

Install a handler for SIGALRM, then use alarm() or ualarm() before a regular blocking recv(). If the alarm goes off, the recv() will return an error with errno set to EINTR.

How to put a List<class> into a JSONObject and then read that object?

Let us assume that the class is Data with two objects name and dob which are both strings.

Initially, check if the list is empty. Then, add the objects from the list to a JSONArray

JSONArray allDataArray = new JSONArray();
List<Data> sList = new ArrayList<String>();

    //if List not empty
    if (!(sList.size() ==0)) {

        //Loop index size()
        for(int index = 0; index < sList.size(); index++) {
            JSONObject eachData = new JSONObject();
            try {
                eachData.put("name", sList.get(index).getName());
                eachData.put("dob", sList.get(index).getDob());
            } catch (JSONException e) {
    } else {
        //Do something when sList is empty

Finally, add the JSONArray to a JSONObject.

JSONObject root = new JSONObject();
    try {
        root.put("data", allDataArray);
    } catch (JSONException e) {

You can further get this data as a String too.

String jsonString = root.toString();

Groovy: How to check if a string contains any element of an array?

def valid = pointAddress.findAll { a ->
    validPointTypes.any { a.contains(it) }

Should do it

make div's height expand with its content

Use the span tag with display:inline-block css attached to it. You can then use CSS and manipulate it like a div in lots of ways but if you don't include a width or height it expands and retracts based on its content.

Hope that helps.

how do I create an array in jquery?

You may be confusing Javascript arrays with PHP arrays. In PHP, arrays are very flexible. They can either be numerically indexed or associative, or even mixed.

array('Item 1', 'Item 2', 'Items 3')  // numerically indexed array
array('first' => 'Item 1', 'second' => 'Item 2')  // associative array
array('first' => 'Item 1', 'Item 2', 'third' => 'Item 3')

Other languages consider these two to be different things, Javascript being among them. An array in Javascript is always numerically indexed:

['Item 1', 'Item 2', 'Item 3']  // array (numerically indexed)

An "associative array", also called Hash or Map, technically an Object in Javascript*, works like this:

{ first : 'Item 1', second : 'Item 2' }  // object (a.k.a. "associative array")

They're not interchangeable. If you need "array keys", you need to use an object. If you don't, you make an array.

* Technically everything is an Object in Javascript, please put that aside for this argument. ;)

jQuery DataTable overflow and text-wrapping issues

I settled for the limitation (to some people a benefit) of having my rows only one line of text high. The CSS to contain long strings then becomes:

.datatable td {
  overflow: hidden; /* this is what fixes the expansion */
  text-overflow: ellipsis; /* not supported in all browsers, but I accepted the tradeoff */
  white-space: nowrap;

[edit to add:] After using my own code and initially failing, I recognized a second requirement that might help people. The table itself needs to have a fixed layout or the cells will just keep trying to expand to accomodate contents no matter what. If DataTables styles or your own styles don't already do so, you need to set it:

table.someTableClass {
  table-layout: fixed

Now that text is truncated with ellipses, to actually "see" the text that is potentially hidden you can implement a tooltip plugin or a details button or something. But a quick and dirty solution is to use JavaScript to set each cell's title to be identical to its contents. I used jQuery, but you don't have to:

  $('.datatable tbody td').each(function(index){
    $this = $(this);
    var titleVal = $this.text();
    if (typeof titleVal === "string" && titleVal !== '') {
      $this.attr('title', titleVal);

DataTables also provides callbacks at the row and cell rendering levels, so you could provide logic to set the titles at that point instead of with a jQuery.each iterator. But if you have other listeners that modify cell text, you might just be better off hitting them with the jQuery.each at the end.

This entire truncation method will ALSO have a limitation you've indicated you're not a fan of: by default columns will have the same width. I identify columns that are going to be consistently wide or consistently narrow, and explicitly set a percentage-based width on them (you could do it in your markup or with sWidth). Any columns without an explicit width get even distribution of the remaining space.

That might seem like a lot of compromises, but the end result was worth it for me.

How to execute a JavaScript function when I have its name as a string

Depending on where you are you can also use:


or, in nodejs


How to set the text/value/content of an `Entry` widget using a button in tkinter

You might want to use insert method. You can find the documentation for the Tkinter Entry Widget here.

This script inserts a text into Entry. The inserted text can be changed in command parameter of the Button.

from tkinter import *

def set_text(text):

win = Tk()

e = Entry(win,width=10)

b1 = Button(win,text="animal",command=lambda:set_text("animal"))

b2 = Button(win,text="plant",command=lambda:set_text("plant"))


Simplest SOAP example

Simplest example would consist of:

  1. Getting user input.
  2. Composing XML SOAP message similar to this

    <soap:Envelope xmlns:xsi=""
        <GetInfoByZIP xmlns="http://www.webserviceX.NET">
  3. POSTing message to webservice url using XHR

  4. Parsing webservice's XML SOAP response similar to this

    <soap:Envelope xmlns:soap=""
      <GetInfoByZIPResponse xmlns="http://www.webserviceX.NET">
        <NewDataSet xmlns="">
  5. Presenting results to user.

But it's a lot of hassle without external JavaScript libraries.

Interactive shell using Docker Compose

This question is very interesting for me because I have problems, when I run container after execution finishes immediately exit and I fixed with -it:

docker run -it -p 3000:3000 -v /app/node_modules -v $(pwd):/app <your_container_id>

And when I must automate it with docker compose:

version: '3'
        stdin_open: true
        tty: true
            context: .
            - "3000:3000"
            - /app/node_modules
            - .:/app

This makes the trick: stdin_open: true, tty: true

This is a project generated with create-react-app it looks this that:

FROM node:alpine

WORKDIR '/app'

COPY package.json .
RUN npm install

COPY . . 

CMD ["npm", "run", "start"]

Hope this example will help other to run a frontend(react in example) into docker container.

How do I find out if the GPS of an Android device is enabled

Kotlin Solution :

private fun locationEnabled() : Boolean {
    val locationManager = getSystemService(Context.LOCATION_SERVICE) as LocationManager
    return locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)

PDF files do not open in Internet Explorer with Adobe Reader 10.0 - users get an empty gray screen. How can I fix this for my users?

It's been 4 months since asking this question, and I still haven't found a good solution.
However, I did find a decent workaround, which I will share in case others have the same issue.
I will try to update this answer, too, if I make further progress.

First of all, my research has shown that there are several possible combinations of user-settings and site settings that cause a variety of PDF display issues. These include:

  • Broken version of Adobe Reader (10.0.*)
  • HTTPS site with Internet Explorer and the default setting "Don't save encrypted files to disk"
  • Adobe Reader setting - disable "Display PDF files in my browser"
  • Slow hardware (thanks @ahochhaus)

I spent some time researching PDF display options at, which is an EXCELLENT resource and I learned a lot.

The workaround I came up with is to embed the PDF file inside an empty HTML page. It is very simple: See some similar examples at

        <object data="/pdf/sample.pdf" type="application/pdf" height="100%" width="100%"></object>

However, here's a list of caveats:

  • This ignores all user-preferences for PDFs - for example, I personally like PDFs to open in a stand-alone Adobe Reader, but that is ignored
  • This doesn't work if you don't have the Adobe Reader plugin installed/enabled, so I added a "Get Adobe Reader" section to the html, and a link to download the file, which usually gets completely hidden by the <object /> tag, ... but ...
  • In Internet Explorer, if the plugin fails to load, the empty object will still hide the "Get Adobe Reader" section, so I had to set the z-index to show it ... but ...
  • Google Chrome's built-in PDF viewer also displays the "Get Adobe Reader" section on top of the PDF, so I had to do browser detection to determine whether to show the "Get Reader".

This is a huge list of caveats. I believe it covers all the bases, but I am definitely not comfortable applying this to EVERY user (most of whom do not have an issue).
Therefore, we decided to ONLY do this embedded option if the user opts-in for it. On our PDF page, we have a section that says "Having trouble viewing PDFs?", which lets you change your setting to "embedded", and we store that setting in a cookie.
In our GetPDF Action, we look for the embed=true cookie. This determines whether we return the PDF file, or if we return a View of HTML with the embedded PDF.

Ugh. This was even less fun than writing IE6-compatible JavaScript.
I hope that others with the same problem can find comfort knowing that they're not alone!

Chaining Observables in RxJS

About promise composition vs. Rxjs, as this is a frequently asked question, you can refer to a number of previously asked questions on SO, among which :

Basically, flatMap is the equivalent of Promise.then.

For your second question, do you want to replay values already emitted, or do you want to process new values as they arrive? In the first case, check the publishReplay operator. In the second case, standard subscription is enough. However you might need to be aware of the cold. vs. hot dichotomy depending on your source (cf. Hot and Cold observables : are there 'hot' and 'cold' operators? for an illustrated explanation of the concept)

How to get ELMAH to work with ASP.NET MVC [HandleError] attribute?

You can subclass HandleErrorAttribute and override its OnException member (no need to copy) so that it logs the exception with ELMAH and only if the base implementation handles it. The minimal amount of code you need is as follows:

using System.Web.Mvc;
using Elmah;

public class HandleErrorAttribute : System.Web.Mvc.HandleErrorAttribute
    public override void OnException(ExceptionContext context)
        if (!context.ExceptionHandled) 
        var httpContext = context.HttpContext.ApplicationInstance.Context;
        var signal = ErrorSignal.FromContext(httpContext);
        signal.Raise(context.Exception, httpContext);

The base implementation is invoked first, giving it a chance to mark the exception as being handled. Only then is the exception signaled. The above code is simple and may cause issues if used in an environment where the HttpContext may not be available, such as testing. As a result, you will want code that is that is more defensive (at the cost of being slightly longer):

using System.Web;
using System.Web.Mvc;
using Elmah;

public class HandleErrorAttribute : System.Web.Mvc.HandleErrorAttribute
    public override void OnException(ExceptionContext context)
        if (!context.ExceptionHandled       // if unhandled, will be logged anyhow
            || TryRaiseErrorSignal(context) // prefer signaling, if possible
            || IsFiltered(context))         // filtered?


    private static bool TryRaiseErrorSignal(ExceptionContext context)
        var httpContext = GetHttpContextImpl(context.HttpContext);
        if (httpContext == null)
            return false;
        var signal = ErrorSignal.FromContext(httpContext);
        if (signal == null)
            return false;
        signal.Raise(context.Exception, httpContext);
        return true;

    private static bool IsFiltered(ExceptionContext context)
        var config = context.HttpContext.GetSection("elmah/errorFilter")
                        as ErrorFilterConfiguration;

        if (config == null)
            return false;

        var testContext = new ErrorFilterModule.AssertionHelperContext(
        return config.Assertion.Test(testContext);

    private static void LogException(ExceptionContext context)
        var httpContext = GetHttpContextImpl(context.HttpContext);
        var error = new Error(context.Exception, httpContext);

    private static HttpContext GetHttpContextImpl(HttpContextBase context)
        return context.ApplicationInstance.Context;

This second version will try to use error signaling from ELMAH first, which involves the fully configured pipeline like logging, mailing, filtering and what have you. Failing that, it attempts to see whether the error should be filtered. If not, the error is simply logged. This implementation does not handle mail notifications. If the exception can be signaled then a mail will be sent if configured to do so.

You may also have to take care that if multiple HandleErrorAttribute instances are in effect then duplicate logging does not occur, but the above two examples should get your started.

SQL Server Restore Error - Access is Denied

I was having the same problem. It turned out that my SQL Server and SQL Server Agent services logon as were running under the Network Services account which didn't have write access to perform the restore of the back up.

I changed both of these services to logon on as Local System Account and this fixed the problem.

Find all files with a filename beginning with a specified string?

Use find with a wildcard:

find . -name 'mystring*'

Git push failed, "Non-fast forward updates were rejected"

I encountered the same error, just add "--force" to the command, it works

git push origin master --force

How to wrap text in LaTeX tables?

Simple like a piece of CAKE!

You can define a new column type like (L in this case) while maintaining the current alignment (c, r or l):



        Title 1 & Title 2 & Title 3 \\
        one-liner & multi-line and centered & \multicolumn{1}{m{3cm}|}{multi-line piece of text to show case a multi-line and justified cell}   \\
        apple & orange & banana \\
        apple & orange & banana \\

enter image description here

What is difference between sjlj vs dwarf vs seh?

SJLJ (setjmp/longjmp): – available for 32 bit and 64 bit – not “zero-cost”: even if an exception isn’t thrown, it incurs a minor performance penalty (~15% in exception heavy code) – allows exceptions to traverse through e.g. windows callbacks

DWARF (DW2, dwarf-2) – available for 32 bit only – no permanent runtime overhead – needs whole call stack to be dwarf-enabled, which means exceptions cannot be thrown over e.g. Windows system DLLs.

SEH (zero overhead exception) – will be available for 64-bit GCC 4.8.


text-align:center won't work with form <label> tag (?)

label is an inline element so its width is equal to the width of the text it contains. The browser is actually displaying the label with text-align:center but since the label is only as wide as the text you don't notice.

The best thing to do is to apply a specific width to the label that is greater than the width of the content - this will give you the results you want.

What is path of JDK on Mac ?

The location has changed from Java 6 (provided by Apple) to Java 7 and onwards (provided by Oracle). The best generic way to find this out is to run


This is the natively supported way to find out both the path to the default Java installation as well as all alternative ones present.

If you check out its help text (java_home -h), you'll see that you can use this command to reliably start a Java program on OS X (java_home --exec ...), with the ability to explicitly specify the desired Java version and architecture, or even request the user to install it if missing.

A more pedestrian approach, but one which will help you trace specifically which Java installation the command java resolves into, goes like this:

  1. run

    which java
  2. if that gives you something like /usr/bin/java, which is a symbolic link to the real location, run

    ls -l `which java`

    On my system, this outputs

    /usr/bin/java -> /Library/Java/JavaVirtualMachines/jdk1.7.0_25.jdk/Contents/Home/bin/java

    and therefrom you can read the Java home directory;

  3. if usr/bin/java points to another symbolic link, recursively apply the same approach with

    ls -l <whatever the /usr/bin/java symlink points to>

An important variation is the setup you get if you start by installing Apple's Java and later install Oracle's. In that case Step 2 above will give you

/usr/bin/java -> /System/Library/Frameworks/JavaVM.framework/Commands/java

and that particular java binary is a stub which will resolve the actual java command to call by consulting the JAVA_HOME environment variable and, if it's not set or doesn't point to a Java home directory, will fall back to calling java_home. It is important to have this in mind when debugging your setup.

Using IF ELSE statement based on Count to execute different Insert statements

If this is in SQL Server, your syntax is correct; however, you need to reference the COUNT(*) as the Total Count from your nested query. This should give you what you need:

  SELECT [Some Column], COUNT(*) TotalCount
  WHERE [Some Column] = 'Target Data'
  GROUP BY [Some Column]
) DerivedTable

Using this, you could assign TotalCount to a variable and then use an IF ELSE statement to execute your INSERT statements:

DECLARE @TotalCount int
SELECT @TotalCount = TotalCount FROM
  SELECT [Some Column], COUNT(*) TotalCount
  WHERE [Some Column] = 'Target Data'
  GROUP BY [Some Column]
) DerivedTable
IF @TotalCount > 0

IntelliJ cannot find any declarations

One of the reason can be that it is not able to detect the pom.xml(or gradle file) and thats why not able to set it as a maven project(or gradle).

You can manually set it up as a maven(or gradle) project by selecting your pom.xml(or gradle file)

How to parse a month name (string) to an integer for comparison in C#?

One simply solution would be create a Dictionary with names and values. Then using Contains() you can find the right value.

Dictionary<string, string> months = new Dictionary<string, string>()
                { "january", "01"},
                { "february", "02"},
                { "march", "03"},
                { "april", "04"},
                { "may", "05"},
                { "june", "06"},
                { "july", "07"},
                { "august", "08"},
                { "september", "09"},
                { "october", "10"},
                { "november", "11"},
                { "december", "12"},
foreach (var month in months)
    if (StringThatContainsMonth.ToLower().Contains(month.Key))
        string thisMonth = month.Value;

What throws an IOException in Java?

Java documentation is helpful to know the root cause of a particular IOException.

Just have a look at the direct known sub-interfaces of IOException from the documentation page:

ChangedCharSetException, CharacterCodingException, CharConversionException, ClosedChannelException, EOFException, FileLockInterruptionException, FileNotFoundException, FilerException, FileSystemException, HttpRetryException, IIOException, InterruptedByTimeoutException, InterruptedIOException, InvalidPropertiesFormatException, JMXProviderException, JMXServerErrorException, MalformedURLException, ObjectStreamException, ProtocolException, RemoteException, SaslException, SocketException, SSLException, SyncFailedException, UnknownHostException, UnknownServiceException, UnsupportedDataTypeException, UnsupportedEncodingException, UserPrincipalNotFoundException, UTFDataFormatException, ZipException

Most of these exceptions are self-explanatory.

A few IOExceptions with root causes:

EOFException: Signals that an end of file or end of stream has been reached unexpectedly during input. This exception is mainly used by data input streams to signal the end of the stream.

SocketException: Thrown to indicate that there is an error creating or accessing a Socket.

RemoteException: A RemoteException is the common superclass for a number of communication-related exceptions that may occur during the execution of a remote method call. Each method of a remote interface, an interface that extends java.rmi.Remote, must list RemoteException in its throws clause.

UnknownHostException: Thrown to indicate that the IP address of a host could not be determined (you may not be connected to Internet).

MalformedURLException: Thrown to indicate that a malformed URL has occurred. Either no legal protocol could be found in a specification string or the string could not be parsed.

What are the "spec.ts" files generated by Angular CLI for?

The .spec.ts files are for unit tests for individual components. You can run Karma task runner through ng test. In order to see code coverage of unit test cases for particular components run ng test --code-coverage

How to convert a string Date to long millseconds

using simpledateformat you can easily achieve it.

1) First convert string to java.Date using simpledateformatter.

2) Use getTime method to obtain count of millisecs from date

 public class test {
      public static void main(String[] args) {
      String currentDate = "01-March-2016";
      SimpleDateFormat f = new SimpleDateFormat("dd-MMM-yyyy");
     Date parseDate = f.parse(currentDate);
     long milliseconds = parseDate.getTime();

more Example click here

php.ini: which one?

You can find what is the php.ini file used:

  • By add phpinfo() in a php page and display the page (like the picture under)
  • From the shell, enter: php -i

Next, you can find the information in the Loaded Configuration file (so here it's /user/local/etc/php/php.ini)

Sometimes, you have indicated (none), in this case you just have to put your custom php.ini that you can find here:;a=blob;f=php.ini-production;hb=HEAD

I hope this answer will help.

How to delete history of last 10 commands in shell?

First, type: history and write down the sequence of line numbers you want to remove.

To clear lines from let's say line 1800 to 1815 write the following in terminal:

$ for line in $(seq 1800 1815) ; do history -d 1800; done

If you want to delete the history for the deletion command, add +1 for 1815 = 1816 and history for that sequence + the deletion command will be deleted.

For example :

$ for line in $(seq 1800 1816) ; do history -d 1800; done

How to calculate modulus of large numbers?

This is called modular exponentiation(

Let's assume you have the following expression:

19 ^ 3 mod 7

Instead of powering 19 directly you can do the following:

(((19 mod 7) * 19) mod 7) * 19) mod 7

But this can take also a long time due to a lot of sequential multipliations and so you can multiply on squared values:

x mod N -> x ^ 2 mod N -> x ^ 4 mod -> ... x ^ 2 |log y| mod N

Modular exponentiation algorithm makes assumptions that:

x ^ y == (x ^ |y/2|) ^ 2 if y is even
x ^ y == x * ((x ^ |y/2|) ^ 2) if y is odd

And so recursive modular exponentiation algorithm will look like this in java:

* Modular exponentiation algorithm
* @param x Assumption: x >= 0
* @param y Assumption: y >= 0
* @param N Assumption: N > 0
* @return x ^ y mod N
public static long modExp(long x, long y, long N) {
    if(y == 0)
        return 1 % N;

    long z = modExp(x, Math.abs(y/2), N);

    if(y % 2 == 0)
        return (long) ((Math.pow(z, 2)) % N);
    return (long) ((x * Math.pow(z, 2)) % N);

Special thanks to @chux for found mistake with incorrect return value in case of y and 0 comparison.

How to get first record in each group using Linq

Use it to achieve what you want. Then decide which properties you want to return.

yourList.OrderBy(l => l.Id).GroupBy(l => new { GroupName = l.F1}).Select(r => r.Key.GroupName)

How to Diff between local uncommitted changes and origin

If you want to compare files visually you can use:

git difftool

It will start your diff app automatically for each changed file.

PS: If you did not set a diff app, you can do it like in the example below(I use Winmerge):

git config --global merge.tool winmerge
git config --replace --global mergetool.winmerge.cmd "\"C:\Program Files (x86)\WinMerge\WinMergeU.exe\" -e -u -dl \"Base\" -dr \"Mine\" \"$LOCAL\" \"$REMOTE\" \"$MERGED\""
git config --global mergetool.prompt false

How can I check if a string is null or empty in PowerShell?

I have a PowerShell script I have to run on a computer so out of date that it doesn't have [String]::IsNullOrWhiteSpace(), so I wrote my own.

function IsNullOrWhitespace($str)
    if ($str)
        return ($str -replace " ","" -replace "`t","").Length -eq 0
        return $TRUE