Programs & Examples On #Forex

Use this tag for programming-related questions concerning the foreign exchange market (FOREX). Non-programming questions, and questions asking us to recommend an API, library or other off-site resource, are strictly off-topic.

react hooks useEffect() cleanup for only componentWillUnmount?

you can use more than one useEffect

for example if my variable is data1 i can use all of this in my component

useEffect( () => console.log("mount"), [] );
useEffect( () => console.log("will update data1"), [ data1 ] );
useEffect( () => console.log("will update any") );
useEffect( () => () => console.log("will update data1 or unmount"), [ data1 ] );
useEffect( () => () => console.log("unmount"), [] );

How to include js and CSS in JSP with spring MVC

you need declare resources in dispatcher servelet file.below is two declarations

<mvc:annotation-driven />
<mvc:resources location="/resources/" mapping="/resources/**" />

How do I remove all null and empty string values from an object?

Note: this doen't sanitize arrays:

import { isPlainObject } from 'lodash';

export const sanitize = (obj: {}) => {
  if (isPlainObject(obj)) {
    const sanitizedObj = {};

    for (const key in obj) {
      if (obj[key]) {
        sanitizedObj[key] = sanitize(obj[key]);

    return sanitizedObj;
  } else {
    return obj;


  describe('sanitize', () => {
    it('should keep an object if there are no empty fields', () => {
      expect(sanitize({ foo: 'bar' })).toEqual({ foo: 'bar' });
      expect(sanitize({ content: { foo: 'bar' } })).toEqual({
        content: { foo: 'bar' },

    it('should remove empty fields from top level', () => {
      expect(sanitize({ foo: '', bar: 'baz' })).toEqual({ bar: 'baz' });
      expect(sanitize({ foo: null, bar: 'baz' })).toEqual({ bar: 'baz' });
      expect(sanitize({ foo: undefined, bar: 'baz' })).toEqual({ bar: 'baz' });

    it('should remove nested empty fields', () => {
      expect(sanitize({ content: { foo: '', bar: 'baz' } })).toEqual({
        content: { bar: 'baz' },
      expect(sanitize({ content: { foo: null, bar: 'baz' } })).toEqual({
        content: { bar: 'baz' },
      expect(sanitize({ content: { foo: undefined, bar: 'baz' } })).toEqual({
        content: { bar: 'baz' },

UTF-8 output from PowerShell

This is a bug in .NET. When PowerShell launches, it caches the output handle (Console.Out). The Encoding property of that text writer does not pick up the value StandardOutputEncoding property.

When you change it from within PowerShell, the Encoding property of the cached output writer returns the cached value, so the output is still encoded with the default encoding.

As a workaround, I would suggest not changing the encoding. It will be returned to you as a Unicode string, at which point you can manage the encoding yourself.

Caching example:

102 [C:\Users\leeholm]
>> $r1 = [Console]::Out

103 [C:\Users\leeholm]
>> $r1

Encoding                                          FormatProvider
--------                                          --------------
System.Text.SBCSCodePageEncoding                  en-US

104 [C:\Users\leeholm]
>> [Console]::OutputEncoding = [System.Text.Encoding]::UTF8

105 [C:\Users\leeholm]
>> $r1

Encoding                                          FormatProvider
--------                                          --------------
System.Text.SBCSCodePageEncoding                  en-US

iOS 7: UITableView shows under status bar

I think the approach to using UITableViewController might be a little bit different from what you have done before. It has worked for me, but you might not be a fan of it. What I have done is have a view controller with a container view that points to my UItableViewController. This way I am able to use the TopLayoutGuide provided to my in storyboard. Just add the constraint to the container view and you should be taken care of for both iOS7 and iOS6.

Obtaining ExitCode using Start-Process and WaitForExit instead of -Wait

The '-Wait' option seemed to block for me even though my process had finished.

I tried Adrian's solution and it works. But I used Wait-Process instead of relying on a side effect of retrieving the process handle.


$proc = Start-Process $msbuild -PassThru
Wait-Process -InputObject $proc

if ($proc.ExitCode -ne 0) {
    Write-Warning "$_ exited with status code $($proc.ExitCode)"

There is already an open DataReader associated with this Command which must be closed first

For those finding this via Google;
I was getting this error because, as suggested by the error, I failed to close a SqlDataReader prior to creating another on the same SqlCommand, mistakenly assuming that it would be garbage collected when leaving the method it was created in.

I solved the issue by calling sqlDataReader.Close(); before creating the second reader.

Executing Batch File in C#

Have you tried starting it as an administrator? Start Visual Studio as an administrator if you use it, because working with .bat files requires those privileges.

Hide console window from Process.Start C#

This doesn't show the window:

Process cmd = new Process();
cmd.StartInfo.FileName = "cmd.exe";
cmd.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
cmd.StartInfo.CreateNoWindow = true;


How to run console application from Windows Service?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.ServiceProcess;
using System.Runtime.InteropServices;

namespace SystemControl
    class Services
        static string strPath = @"D:\";
        static void Main(string[] args)
            string strServiceName = "WindowsService1";
            string svcPath = @"D:\Applications\MSC\Agent\bin\WindowsService1.exe";
            if (!IsInstalled(strServiceName))
                InstallAndStart(strServiceName, strServiceName, svcPath + " -k runservice");                
                Console.Write(strServiceName + " already installed. Do you want to Uninstalled the Service.Y/N.?");
                string strKey = Console.ReadLine();

                if (!string.IsNullOrEmpty(strKey) && (strKey.StartsWith("y")|| strKey.StartsWith("Y")))
                    ServiceLogs(strServiceName + " Uninstalled.!", strPath);
                    Console.Write(strServiceName + " Uninstalled.!");

        #region "Environment Variables"
        public static string GetEnvironment(string name, bool ExpandVariables = true)
            if (ExpandVariables)
                return System.Environment.GetEnvironmentVariable(name);
                return (string)Microsoft.Win32.Registry.LocalMachine.OpenSubKey(@"SYSTEM\CurrentControlSet\Control\Session Manager\Environment\").GetValue(name, "", Microsoft.Win32.RegistryValueOptions.DoNotExpandEnvironmentNames);

        public static void SetEnvironment(string name, string value)
            System.Environment.SetEnvironmentVariable(name, value);

        #region "ServiceCalls Native"
        public static ServiceController[] List { get { return ServiceController.GetServices(); } }

        public static void Start(string serviceName, int timeoutMilliseconds)
            ServiceController service = new ServiceController(serviceName);
                TimeSpan timeout = TimeSpan.FromMilliseconds(timeoutMilliseconds);

                service.WaitForStatus(ServiceControllerStatus.Running, timeout);
            catch(Exception ex)
                // ...

        public static void Stop(string serviceName, int timeoutMilliseconds)
            ServiceController service = new ServiceController(serviceName);
                TimeSpan timeout = TimeSpan.FromMilliseconds(timeoutMilliseconds);

                service.WaitForStatus(ServiceControllerStatus.Stopped, timeout);
                // ...

        public static void Restart(string serviceName, int timeoutMilliseconds)
            ServiceController service = new ServiceController(serviceName);
                int millisec1 = Environment.TickCount;
                TimeSpan timeout = TimeSpan.FromMilliseconds(timeoutMilliseconds);

                service.WaitForStatus(ServiceControllerStatus.Stopped, timeout);

                // count the rest of the timeout
                int millisec2 = Environment.TickCount;
                timeout = TimeSpan.FromMilliseconds(timeoutMilliseconds - (millisec2 - millisec1));

                service.WaitForStatus(ServiceControllerStatus.Running, timeout);
                // ...

        public static bool IsInstalled(string serviceName)
            // get list of Windows services
            ServiceController[] services = ServiceController.GetServices();

            // try to find service name
            foreach (ServiceController service in services)
                if (service.ServiceName == serviceName)
                    return true;
            return false;

        #region "ServiceCalls API"
        private const int STANDARD_RIGHTS_REQUIRED = 0xF0000;
        private const int SERVICE_WIN32_OWN_PROCESS = 0x00000010;

        public enum ServiceManagerRights
            Connect = 0x0001,
            CreateService = 0x0002,
            EnumerateService = 0x0004,
            Lock = 0x0008,
            QueryLockStatus = 0x0010,
            ModifyBootConfig = 0x0020,
            StandardRightsRequired = 0xF0000,
            AllAccess = (StandardRightsRequired | Connect | CreateService |
            EnumerateService | Lock | QueryLockStatus | ModifyBootConfig)

        public enum ServiceRights
            QueryConfig = 0x1,
            ChangeConfig = 0x2,
            QueryStatus = 0x4,
            EnumerateDependants = 0x8,
            Start = 0x10,
            Stop = 0x20,
            PauseContinue = 0x40,
            Interrogate = 0x80,
            UserDefinedControl = 0x100,
            Delete = 0x00010000,
            StandardRightsRequired = 0xF0000,
            AllAccess = (StandardRightsRequired | QueryConfig | ChangeConfig |
            QueryStatus | EnumerateDependants | Start | Stop | PauseContinue |
            Interrogate | UserDefinedControl)

        public enum ServiceBootFlag
            Start = 0x00000000,
            SystemStart = 0x00000001,
            AutoStart = 0x00000002,
            DemandStart = 0x00000003,
            Disabled = 0x00000004

        public enum ServiceState
            Unknown = -1, // The state cannot be (has not been) retrieved.
            NotFound = 0, // The service is not known on the host server.
            Stop = 1, // The service is NET stopped.
            Run = 2, // The service is NET started.
            Stopping = 3,
            Starting = 4,

        public enum ServiceControl
            Stop = 0x00000001,
            Pause = 0x00000002,
            Continue = 0x00000003,
            Interrogate = 0x00000004,
            Shutdown = 0x00000005,
            ParamChange = 0x00000006,
            NetBindAdd = 0x00000007,
            NetBindRemove = 0x00000008,
            NetBindEnable = 0x00000009,
            NetBindDisable = 0x0000000A

        public enum ServiceError
            Ignore = 0x00000000,
            Normal = 0x00000001,
            Severe = 0x00000002,
            Critical = 0x00000003

        private class SERVICE_STATUS
            public int dwServiceType = 0;
            public ServiceState dwCurrentState = 0;
            public int dwControlsAccepted = 0;
            public int dwWin32ExitCode = 0;
            public int dwServiceSpecificExitCode = 0;
            public int dwCheckPoint = 0;
            public int dwWaitHint = 0;

        [DllImport("advapi32.dll", EntryPoint = "OpenSCManagerA")]
        private static extern IntPtr OpenSCManager(string lpMachineName, string lpDatabaseName, ServiceManagerRights dwDesiredAccess);
        [DllImport("advapi32.dll", EntryPoint = "OpenServiceA", CharSet = CharSet.Ansi)]
        private static extern IntPtr OpenService(IntPtr hSCManager, string lpServiceName, ServiceRights dwDesiredAccess);
        [DllImport("advapi32.dll", EntryPoint = "CreateServiceA")]
        private static extern IntPtr CreateService(IntPtr hSCManager, string lpServiceName, string lpDisplayName, ServiceRights dwDesiredAccess, int dwServiceType, ServiceBootFlag dwStartType, ServiceError dwErrorControl, string lpBinaryPathName, string lpLoadOrderGroup, IntPtr lpdwTagId, string lpDependencies, string lp, string lpPassword);
        private static extern int CloseServiceHandle(IntPtr hSCObject);
        private static extern int QueryServiceStatus(IntPtr hService, SERVICE_STATUS lpServiceStatus);
        [DllImport("advapi32.dll", SetLastError = true)]
        private static extern int DeleteService(IntPtr hService);
        private static extern int ControlService(IntPtr hService, ServiceControl dwControl, SERVICE_STATUS lpServiceStatus);
        [DllImport("advapi32.dll", EntryPoint = "StartServiceA")]
        private static extern int StartService(IntPtr hService, int dwNumServiceArgs, int lpServiceArgVectors);

        /// <summary>
        /// Takes a service name and tries to stop and then uninstall the windows serviceError
        /// </summary>
        /// <param name="ServiceName">The windows service name to uninstall</param>
        public static void Uninstall(string ServiceName)
            IntPtr scman = OpenSCManager(ServiceManagerRights.Connect);
                IntPtr service = OpenService(scman, ServiceName, ServiceRights.StandardRightsRequired | ServiceRights.Stop | ServiceRights.QueryStatus);
                if (service == IntPtr.Zero)
                    throw new ApplicationException("Service not installed.");
                    int ret = DeleteService(service);
                    if (ret == 0)
                        int error = Marshal.GetLastWin32Error();
                        throw new ApplicationException("Could not delete service " + error);

        /// <summary>
        /// Accepts a service name and returns true if the service with that service name exists
        /// </summary>
        /// <param name="ServiceName">The service name that we will check for existence</param>
        /// <returns>True if that service exists false otherwise</returns>
        public static bool ServiceIsInstalled(string ServiceName)
            IntPtr scman = OpenSCManager(ServiceManagerRights.Connect);
                IntPtr service = OpenService(scman, ServiceName,
                if (service == IntPtr.Zero) return false;
                return true;

        /// <summary>
        /// Takes a service name, a service display name and the path to the service executable and installs / starts the windows service.
        /// </summary>
        /// <param name="ServiceName">The service name that this service will have</param>
        /// <param name="DisplayName">The display name that this service will have</param>
        /// <param name="FileName">The path to the executable of the service</param>
        public static void InstallAndStart(string ServiceName, string DisplayName,
        string FileName)
            IntPtr scman = OpenSCManager(ServiceManagerRights.Connect |
                string strKey = string.Empty;
                IntPtr service = OpenService(scman, ServiceName,
                ServiceRights.QueryStatus | ServiceRights.Start);
                if (service == IntPtr.Zero)
                    service = CreateService(scman, ServiceName, DisplayName,
                    ServiceRights.QueryStatus | ServiceRights.Start, SERVICE_WIN32_OWN_PROCESS,
                    ServiceBootFlag.AutoStart, ServiceError.Normal, FileName, null, IntPtr.Zero,
                    null, null, null);
                    ServiceLogs(ServiceName + " Installed Sucessfully.!", strPath);
                    Console.Write(ServiceName + " Installed Sucessfully.! Do you want to Start the Service.Y/N.?");
                if (service == IntPtr.Zero)
                    ServiceLogs("Failed to install service.", strPath);
                    throw new ApplicationException("Failed to install service.");
                    if (!string.IsNullOrEmpty(strKey) && (strKey.StartsWith("y") || strKey.StartsWith("Y")))
                        ServiceLogs(ServiceName + " Started Sucessfully.!", strPath);
                        Console.Write(ServiceName + " Started Sucessfully.!");

        /// <summary>
        /// Takes a service name and starts it
        /// </summary>
        /// <param name="Name">The service name</param>
        public static void StartService(string Name)
            IntPtr scman = OpenSCManager(ServiceManagerRights.Connect);
                IntPtr hService = OpenService(scman, Name, ServiceRights.QueryStatus |
                if (hService == IntPtr.Zero)
                    ServiceLogs("Could not open service.", strPath);
                    throw new ApplicationException("Could not open service.");

        /// <summary>
        /// Stops the provided windows service
        /// </summary>
        /// <param name="Name">The service name that will be stopped</param>
        public static void StopService(string Name)
            IntPtr scman = OpenSCManager(ServiceManagerRights.Connect);
                IntPtr hService = OpenService(scman, Name, ServiceRights.QueryStatus |
                if (hService == IntPtr.Zero)
                    ServiceLogs("Could not open service.", strPath);
                    throw new ApplicationException("Could not open service.");


        /// <summary>
        /// Stars the provided windows service
        /// </summary>
        /// <param name="hService">The handle to the windows service</param>
        private static void StartService(IntPtr hService)
            SERVICE_STATUS status = new SERVICE_STATUS();
            StartService(hService, 0, 0);
            WaitForServiceStatus(hService, ServiceState.Starting, ServiceState.Run);

        /// <summary>
        /// Stops the provided windows service
        /// </summary>
        /// <param name="hService">The handle to the windows service</param>
        private static void StopService(IntPtr hService)
            SERVICE_STATUS status = new SERVICE_STATUS();
            ControlService(hService, ServiceControl.Stop, status);
            WaitForServiceStatus(hService, ServiceState.Stopping, ServiceState.Stop);

        /// <summary>
        /// Takes a service name and returns the <code>ServiceState</code> of the corresponding service
        /// </summary>
        /// <param name="ServiceName">The service name that we will check for his <code>ServiceState</code></param>
        /// <returns>The ServiceState of the service we wanted to check</returns>
        public static ServiceState GetServiceStatus(string ServiceName)
            IntPtr scman = OpenSCManager(ServiceManagerRights.Connect);
                IntPtr hService = OpenService(scman, ServiceName,
                if (hService == IntPtr.Zero)
                    return ServiceState.NotFound;
                    return GetServiceStatus(hService);

        /// <summary>
        /// Gets the service state by using the handle of the provided windows service
        /// </summary>
        /// <param name="hService">The handle to the service</param>
        /// <returns>The <code>ServiceState</code> of the service</returns>
        private static ServiceState GetServiceStatus(IntPtr hService)
            SERVICE_STATUS ssStatus = new SERVICE_STATUS();
            if (QueryServiceStatus(hService, ssStatus) == 0)
                ServiceLogs("Failed to query service status.", strPath);
                throw new ApplicationException("Failed to query service status.");
            return ssStatus.dwCurrentState;

        /// <summary>
        /// Returns true when the service status has been changes from wait status to desired status
        /// ,this method waits around 10 seconds for this operation.
        /// </summary>
        /// <param name="hService">The handle to the service</param>
        /// <param name="WaitStatus">The current state of the service</param>
        /// <param name="DesiredStatus">The desired state of the service</param>
        /// <returns>bool if the service has successfully changed states within the allowed timeline</returns>
        private static bool WaitForServiceStatus(IntPtr hService, ServiceState
        WaitStatus, ServiceState DesiredStatus)
            SERVICE_STATUS ssStatus = new SERVICE_STATUS();
            int dwOldCheckPoint;
            int dwStartTickCount;

            QueryServiceStatus(hService, ssStatus);
            if (ssStatus.dwCurrentState == DesiredStatus) return true;
            dwStartTickCount = Environment.TickCount;
            dwOldCheckPoint = ssStatus.dwCheckPoint;

            while (ssStatus.dwCurrentState == WaitStatus)
                // Do not wait longer than the wait hint. A good interval is
                // one tenth the wait hint, but no less than 1 second and no
                // more than 10 seconds.

                int dwWaitTime = ssStatus.dwWaitHint / 10;

                if (dwWaitTime < 1000) dwWaitTime = 1000;
                else if (dwWaitTime > 10000) dwWaitTime = 10000;


                // Check the status again.

                if (QueryServiceStatus(hService, ssStatus) == 0) break;

                if (ssStatus.dwCheckPoint > dwOldCheckPoint)
                    // The service is making progress.
                    dwStartTickCount = Environment.TickCount;
                    dwOldCheckPoint = ssStatus.dwCheckPoint;
                    if (Environment.TickCount - dwStartTickCount > ssStatus.dwWaitHint)
                        // No progress made within the wait hint
            return (ssStatus.dwCurrentState == DesiredStatus);

        /// <summary>
        /// Opens the service manager
        /// </summary>
        /// <param name="Rights">The service manager rights</param>
        /// <returns>the handle to the service manager</returns>
        private static IntPtr OpenSCManager(ServiceManagerRights Rights)
            IntPtr scman = OpenSCManager(null, null, Rights);
            if (scman == IntPtr.Zero)
                    throw new ApplicationException("Could not connect to service control manager.");
                catch (Exception ex)
            return scman;


        private static void CreateFolderStructure(string path)
                System.IO.Directory.CreateDirectory(path+ "Applications");
            if (!System.IO.Directory.Exists(path + "Applications\\MSC"))
                System.IO.Directory.CreateDirectory(path + "Applications\\MSC");
            if (!System.IO.Directory.Exists(path + "Applications\\MSC\\Agent"))
                System.IO.Directory.CreateDirectory(path + "Applications\\MSC\\Agent");
            if (!System.IO.Directory.Exists(path + "Applications\\MSC\\Agent\\bin"))
                System.IO.Directory.CreateDirectory(path + "Applications\\MSC\\Agent\\bin");
            if (!System.IO.Directory.Exists(path + "Applications\\MSC\\AgentService"))
                System.IO.Directory.CreateDirectory(path + "Applications\\MSC\\AgentService");

            string fullPath = System.IO.Path.GetFullPath("MSCService");
            if (System.IO.Directory.Exists(fullPath))
                foreach (string strFile in System.IO.Directory.GetFiles(fullPath))
                    if (System.IO.File.Exists(strFile))
                        String[] strArr = strFile.Split('\\');
                        System.IO.File.Copy(strFile, path + "Applications\\MSC\\Agent\\bin\\"+ strArr[strArr.Count()-1], true);

        private static void ServiceLogs(string strLogInfo, string path)
            string filePath = path + "Applications\\MSC\\AgentService\\ServiceLogs.txt";            
            System.IO.File.AppendAllLines(filePath, (strLogInfo + "--" + DateTime.Now.ToString()).ToString().Split('|'));

How to execute an .SQL script file using c#

Added additional improvements to surajits answer:

using System;
using Microsoft.SqlServer.Management.Smo;
using Microsoft.SqlServer.Management.Common;
using System.IO;
using System.Data.SqlClient;

namespace MyNamespace
    public partial class RunSqlScript : System.Web.UI.Page
        protected void Page_Load(object sender, EventArgs e)
            var connectionString = @"your-connection-string";
            var pathToScriptFile = Server.MapPath("~/sql-scripts/") + "sql-script.sql";
            var sqlScript = File.ReadAllText(pathToScriptFile);

            using (var connection = new SqlConnection(connectionString))
                var server = new Server(new ServerConnection(connection));

Also, I had to add the following references to my project:

  • C:\Program Files\Microsoft SQL Server\120\SDK\Assemblies\Microsoft.SqlServer.ConnectionInfo.dll
  • C:\Program Files\Microsoft SQL Server\120\SDK\Assemblies\Microsoft.SqlServer.Smo.dll

I have no idea if those are the right dll:s to use since there are several folders in C:\Program Files\Microsoft SQL Server but in my application these two work.

Execute multiple command lines with the same process using .NET

A command-line process such cmd.exe or mysql.exe will usually read (and execute) whatever you (the user) type in (at the keyboard).

To mimic that, I think you want to use the RedirectStandardInput property:

How to execute a .bat file from a C# windows form app?

Here is what you are looking for:

Service hangs up at WaitForExit after calling batch file

It's about a question as to why a service can't execute a file, but it shows all the code necessary to do so.

How to spawn a process and capture its STDOUT in .NET?

Here's some full and simple code to do this. This worked fine when I used it.

var processStartInfo = new ProcessStartInfo
    FileName = @"C:\SomeProgram",
    Arguments = "Arguments",
    RedirectStandardOutput = true,
    UseShellExecute = false
var process = Process.Start(processStartInfo);
var output = process.StandardOutput.ReadToEnd();

Note that this only captures standard output; it doesn't capture standard error. If you want both, use this technique for each stream.

ProcessStartInfo hanging on "WaitForExit"? Why?

This post maybe outdated but i found out the main cause why it usually hang is due to stack overflow for the redirectStandardoutput or if you have redirectStandarderror.

As the output data or the error data is large, it will cause a hang time as it is still processing for indefinite duration.

so to resolve this issue:

p.StartInfo.RedirectStandardoutput = False
p.StartInfo.RedirectStandarderror = False

Simple JavaScript Checkbox Validation

You can do the following:

<form action="/" onsubmit="if(document.getElementById('agree').checked) { return true; } else { alert('please agree'); return false; }">
    <input type="checkbox" name="checkbox" value="check" id="agree" />
    <input type="submit" name="email_submit" value="submit" />

Here is a working demo -

How to obtain the query string from the current URL with JavaScript?

  var queryObj = {};
     var queryString = url.split("?")[1];

now you have the query part in queryString

First replace will remove all the white spaces, second will replace all the '&' part with "," and finally the third replace will put ":" in place of '=' signs.

queryObj = JSON.parse('{"' + queryString.replace(/"/g, '\\"').replace(/&/g, '","').replace(/=/g,'":"') + '"}')

So let say you had a query like abc=123&efg=456. Now before parsing, your query is being converted into something like {"abc":"123","efg":"456"}. Now when you will parse this, it will give you your query in json object.

get enum name from enum value

Say we have:

public enum MyEnum {
  Test1, Test2, Test3

To get the name of a enum variable use name():

MyEnum e = MyEnum.Test1;
String name =; // Returns "Test1"

To get the enum from a (string) name, use valueOf():

String name = "Test1";
MyEnum e = Enum.valueOf(MyEnum.class, name);

If you require integer values to match enum fields, extend the enum class:

public enum MyEnum {
  Test1(1), Test2(2), Test3(3);

  public final int value;

  MyEnum(final int value) {
     this.value = value;

Now you can use:

MyEnum e = MyEnum.Test1;
int value = e.value; // = 1

And lookup the enum using the integer value:

MyEnum getValue(int value) {
  for(MyEnum e: MyEunm.values()) {
    if(e.value == value) {
      return e;
  return null;// not found

How to use npm with ASP.NET Core

Much simpler approach is to use OdeToCode.UseNodeModules Nuget package. I just tested it with .Net Core 3.0. All you need to do is add the package to the solution and reference it in the Configure method of the Startup class:


I learned about it from the excellent Building a Web App with ASP.NET Core, MVC, Entity Framework Core, Bootstrap, and Angular Pluralsight course by Shawn Wildermuth.

Get user profile picture by Id

As per the current latest Facebook API version 3.2, For users you can use this generic method for getting profile picture is{user-id}/picture?type=square you can visit documentation for user picture here. The possible values for type parameter in URL can be small, normal, album, large, square

For Groups and Pages, the profile picture is not available directly. You have to get them using access token. For Groups you have to use User Access Token and for Pages you can use both User Access Token and Page Access Token.

You can get Group's or Page's Profile Picture using the generic URL:{user-id}/picture?access_token={access-token}&type=square

I hope this is helpful for people who are looking for Page or Group Profile picture.

cordova run with ios error .. Error code 65 for command: xcodebuild with args:

Try to remove and add ios again

ionic cordova platform remove ios

ionic cordova platform add ios

Worked in my case

JPA & Criteria API - Select only specific columns

You can do something like this

Session session = app.factory.openSession();
CriteriaBuilder builder = session.getCriteriaBuilder();
CriteriaQuery query = builder.createQuery();
Root<Users> root = query.from(Users.class);"firstname"));
String name = session.createQuery(query).getSingleResult();

where you can change "firstname" with the name of the column you want.

Exception in thread "main" java.lang.UnsupportedClassVersionError: a (Unsupported major.minor version 51.0)

Try sudo update-alternatives --config java from the command line to set the version of the JRE you want to use. This should fix it.

Giving UIView rounded corners

Try this

#import <QuartzCore/QuartzCore.h> // not necessary for 10 years now  :)


view.layer.cornerRadius = 5;
view.layer.masksToBounds = true;

Note: If you are trying to apply rounded corners to a UIViewController's view, it should not be applied in the view controller's constructor, but rather in -viewDidLoad, after view is actually instantiated.

How to unset a JavaScript variable?

TLDR: simple defined variables (without var, let, const) could be deleted with delete. If you use var, let, const - they could not be deleted neither with delete nor with Reflect.deleteProperty.

Chrome 55:

simpleVar = "1";
delete simpleVar;
VM439:1 Uncaught ReferenceError: simpleVar is not defined
    at <anonymous>:1:1
(anonymous) @ VM439:1
var varVar = "1";
delete varVar;
let letVar = "1";
delete letVar;
const constVar="1";
delete constVar;
Reflect.deleteProperty (window, "constVar");
Reflect.deleteProperty (window, "varVar");
Reflect.deleteProperty (window, "letVar");

FF Nightly 53.0a1 shows same behaviour.

How can I capitalize the first letter of each word in a string?

Why do you complicate your life with joins and for loops when the solution is simple and safe??

Just do this:

string = "the brown fox"

Debug vs Release in CMake

// CMakeLists.txt : release


// CMakeLists.txt : debug


How to handle ListView click in Android

You have to use setOnItemClickListener someone said.
The code should be like this:

listView.setOnItemClickListener(new OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        // When clicked, show a toast with the TextView text or do whatever you need.
        Toast.makeText(getApplicationContext(), ((TextView) view).getText(), Toast.LENGTH_SHORT).show();

How to import jquery using ES6 syntax?

If you are using Webpack 4, the answer is to use the ProvidePlugin. Their documentation specifically covers angular.js with jquery use case:

new webpack.ProvidePlugin({
  'window.jQuery': 'jquery'

The issue is that when using import syntax angular.js and jquery will always be imported before you have a chance to assign jquery to window.jQuery (import statements will always run first no matter where they are in the code!). This means that angular will always see window.jQuery as undefined until you use ProvidePlugin.

CSS: Truncate table cells, but fit as much as possible

Check if "nowrap" solve the issue to an extent. Note: nowrap is not supported in HTML5

<table border="1" style="width: 100%; white-space: nowrap; table-layout: fixed;">
    <td style="overflow: hidden; text-overflow: ellipsis;" nowrap >This cells has more content  </td>
    <td style="overflow: hidden; text-overflow: ellipsis;" nowrap >Less content here has more content</td>

Android button with icon and text

For anyone looking to do this dynamically then setCompoundDrawables(Drawable left, Drawable top, Drawable right, Drawable bottom) on the buttons object will assist.


Button search = (Button) findViewById(;

Creating a PDF from a RDLC Report in the Background

You can instanciate LocalReport

                FicheInscriptionBean fiche = new FicheInscriptionBean();
                fiche.ToFicheInscriptionBean(inscription);List<FicheInscriptionBean> list = new List<FicheInscriptionBean>();
                ReportDataSource rds = new ReportDataSource();
                rds = new ReportDataSource("InscriptionDataSet", list);
                // attachement du QrCode.
                string stringToCode = numinscription + "," + inscription.Nom + "," + inscription.Prenom + "," + inscription.Cin;
                Bitmap BitmapCaptcha = PostulerFiche.GenerateQrCode(fiche.NumInscription + ":" + fiche.Cin, Brushes.Black, Brushes.White, 200);
                MemoryStream ms = new MemoryStream();
                BitmapCaptcha.Save(ms, ImageFormat.Gif);
                var base64Data = Convert.ToBase64String(ms.ToArray());
                string QR_IMG = base64Data;
                ReportParameter parameter = new ReportParameter("QR_IMG", QR_IMG, true);

                LocalReport report = new LocalReport();
                report.ReportPath = Page.Server.MapPath("~/rdlc/FicheInscription.rdlc");
                report.SetParameters(new ReportParameter[] { parameter });

                string FileName = "FichePreinscription_" + numinscription + ".pdf";
                string extension;
                string encoding;
                string mimeType;
                string[] streams;
                Warning[] warnings;
                Byte[] mybytes = report.Render("PDF", null,
                              out extension, out encoding,
                              out mimeType, out streams, out warnings);
                using (FileStream fs = File.Create(Server.MapPath("~/rdlc/Reports/" + FileName)))
                    fs.Write(mybytes, 0, mybytes.Length);
                Response.Buffer = true;
                Response.Charset = "";
                Response.ContentType = "application/pdf";
                Response.AddHeader("Content-Disposition", "attachment;filename=\"" + FileName + "\"");
                Response.WriteFile(Server.MapPath("~/rdlc/Reports/" + FileName));

                File.Delete(Server.MapPath("~/rdlc/Reports/" + FileName));

How to get next/previous record in MySQL?

In addition to cemkalyoncu's solution:

next record:


previous record:


edit: Since this answer has been getting a few upvotes lately, I really want to stress the comment I made earlier about understanding that a primary key colum is not meant as a column to sort by, because MySQL does not guarantee that higher, auto incremented, values are necessarily added at a later time.

If you don't care about this, and simply need the record with a higher (or lower) id then this will suffice. Just don't use this as a means to determine whether a record is actually added later (or earlier). In stead, consider using a datetime column to sort by, for instance.

Convert data file to blob

A file object is an instance of Blob but a blob object is not an instance of File

new File([], 'foo.txt') === 'File' //true
new File([], 'foo.txt') instanceof File // true
new File([], 'foo.txt') instanceof Blob // true

new Blob([]) === 'Blob' //true
new Blob([]) instanceof Blob //true
new Blob([]) instanceof File // false

new File([], 'foo.txt') === new Blob([]) //false

If you must convert a file object to a blob object, you can create a new Blob object using the array buffer of the file. See the example below.

let file = new File(['hello', ' ', 'world'], 'hello_world.txt', {type: 'text/plain'});
//or let file = document.querySelector('input[type=file]').files[0];
let reader = new FileReader();
reader.onload = function(e) {
    let blob = new Blob([new Uint8Array(], {type: file.type });

As pointed by @bgh you can also use the arrayBuffer method of the File object. See the example below.

let file = new File(['hello', ' ', 'world'], 'hello_world.txt', {type: 'text/plain'});
//or let file = document.querySelector('input[type=file]').files[0];

file.arrayBuffer().then((arrayBuffer) => {
    let blob = new Blob([new Uint8Array(arrayBuffer)], {type: file.type });

If your environment supports async/await you can use a one-liner like below

let fileToBlob = async (file) => new Blob([new Uint8Array(await file.arrayBuffer())], {type: file.type });
console.log(await fileToBlob(new File(['hello', ' ', 'world'], 'hello_world.txt', {type: 'text/plain'})));

Disable developer mode extensions pop up in Chrome

While creating chrome driver, use option to disable it. Its working without any extensions.

Use following code snippet

ChromeOptions options = new ChromeOptions();
System.setProperty("",(System.getProperty("user.dir") + "//src//test//resources//chromedriver_new.exe"));
driver = new ChromeDriver(options);

Find control by name from Windows Forms controls

TextBox tbx = this.Controls.Find("textBox1", true).FirstOrDefault() as TextBox;
tbx.Text = "found!";

If Controls.Find is not found "textBox1" => error. You must add code.

If(tbx != null)


TextBox tbx = this.Controls.Find("textBox1", true).FirstOrDefault() as TextBox;
If(tbx != null)
   tbx.Text = "found!";

How can I slice an ArrayList out of an ArrayList in Java?

I have found a way if you know startIndex and endIndex of the elements one need to remove from ArrayList

Let al be the original ArrayList and startIndex,endIndex be start and end index to be removed from the array respectively:

al.subList(startIndex, endIndex + 1).clear();

How do I count a JavaScript object's attributes?

EDIT: this will case errors with jquery to happen, plus some other inconveniences. YOU SHOULD NOT USE IT: (perhaps if one could add a privaate method instead of a public property function, this would be OK, but don't have the time now). Community wikied

do not use:

Even though javascript's object by default doesn't have the count function, classes are easily extendable, and one can add it oneself:

Object.prototype.count = function () {
    var count = 0;
    for(var prop in this) {
            count = count + 1;
    return count;

So that after that one can execute

var object = {'key1': 'val1', 'key2':'val2', 'key3':'val3'};
console.log(object.count()); // 3

As a conclusion, if you want count functionality in objects, you need to copy the code from code block 1, and paste it early in execution time ( before you call the count ).

Let me know if that works for you!

Regards, Pedro

How can I work with command line on synology?

The current windows 10 (Version 1803 (OS Build 17134.1)) has SSH built in. With that, just enable SSH from the Control Panel, Terminal & SNMP, be sure you are using an account in the Administrator's group, and you're all set.

Launch Powershell or CMD, enter ssh yourAccountName@diskstation

The first time it will cache off your certificate.


Further detailed explanations can be found on the synology docs page:

How to login to DSM with root permission via SSH Telnet

Disable a link in Bootstrap

If what you're trying to do is disable an a link, there is no option to do this. I think you can find an answer that will work for you in this question here.

One option here is to use

<a href="/" onclick="return false;">123n</a>

Disabled href tag

Definition of int64_t

My 2 cents, from a current implementation Point of View and for SWIG users on k8 (x86_64) architecture.


First long long and long int are different types but sizeof(long long) == sizeof(long int) == sizeof(int64_t)


First try to find where and how the compiler define int64_t and uint64_t

grepc -rn "typedef.*INT64_TYPE" /lib/gcc
/lib/gcc/x86_64-linux-gnu/9/include/stdint-gcc.h:43:typedef __INT64_TYPE__ int64_t;
/lib/gcc/x86_64-linux-gnu/9/include/stdint-gcc.h:55:typedef __UINT64_TYPE__ uint64_t;

So we need to find this compiler macro definition

gcc -dM -E -x c /dev/null | grep __INT64                 
#define __INT64_C(c) c ## L
#define __INT64_MAX__ 0x7fffffffffffffffL
#define __INT64_TYPE__ long int

gcc -dM -E -x c++ /dev/null | grep __INT64
#define __INT64_C(c) c ## L
#define __INT64_MAX__ 0x7fffffffffffffffL
#define __INT64_TYPE__ long int


clang -dM -E -x c++ /dev/null | grep INT64_TYPE
#define __INT64_TYPE__ long int
#define __UINT64_TYPE__ long unsigned int

Clang, GNU compilers:
-dM dumps a list of macros.
-E prints results to stdout instead of a file.
-x c and -x c++ select the programming language when using a file without a filename extension, such as /dev/null


note: for swig user, on Linux x86_64 use -DSWIGWORDSIZE64


On Catalina 10.15 IIRC


clang -dM -E -x c++ /dev/null | grep INT64_TYPE
#define __INT64_TYPE__ long long int
#define __UINT64_TYPE__ long long unsigned int

-dM dumps a list of macros.
-E prints results to stdout instead of a file.
-x c and -x c++ select the programming language when using a file without a filename extension, such as /dev/null


note: for swig user, on macOS x86_64 don't use -DSWIGWORDSIZE64

Visual Studio 2019

First sizeof(long int) == 4 and sizeof(long long) == 8

in stdint.h we have:


typedef signed char        int8_t;
typedef short              int16_t;
typedef int                int32_t;
typedef long long          int64_t;
typedef unsigned char      uint8_t;
typedef unsigned short     uint16_t;
typedef unsigned int       uint32_t;
typedef unsigned long long uint64_t;

note: for swig user, on windows x86_64 don't use -DSWIGWORDSIZE64

SWIG Stuff

First see so you can control the typedef using SWIGWORDSIZE64 but...

now the bad: SWIG Java and SWIG CSHARP do not take it into account

So you may want to use

#if defined(SWIGJAVA)
#if defined(SWIGWORDSIZE64)
%clear NEW_TYPE;
%clear NEW_TYPE *;
%clear NEW_TYPE &;
%clear const NEW_TYPE &;
%apply TYPE { NEW_TYPE };
%apply TYPE * { NEW_TYPE * };
%apply TYPE & { NEW_TYPE & };
%apply const TYPE & { const NEW_TYPE & };
PRIMITIVE_TYPEMAP(long int, long long);
PRIMITIVE_TYPEMAP(unsigned long int, long long);
#endif // defined(SWIGWORDSIZE64)
#endif // defined(SWIGJAVA)


#if defined(SWIGCSHARP)
#if defined(SWIGWORDSIZE64)
%clear NEW_TYPE;
%clear NEW_TYPE *;
%clear NEW_TYPE &;
%clear const NEW_TYPE &;
%apply TYPE { NEW_TYPE };
%apply TYPE * { NEW_TYPE * };
%apply TYPE & { NEW_TYPE & };
%apply const TYPE & { const NEW_TYPE & };
PRIMITIVE_TYPEMAP(long int, long long);
PRIMITIVE_TYPEMAP(unsigned long int, unsigned long long);
#endif // defined(SWIGWORDSIZE64)
#endif // defined(SWIGCSHARP)

So int64_t aka long int will be bind to Java/C# long on Linux...

Reordering Chart Data Series

This function gets the series names, puts them into an array, sorts the array and based on that defines the plotting order which will give the desired output.

Function Increasing_Legend_Sort(mychart As Chart)

    Dim Arr()
    ReDim Arr(1 To mychart.FullSeriesCollection.Count)

        'Assigning Series names to an array
        For i = LBound(Arr) To UBound(Arr)
        Arr(i) = mychart.FullSeriesCollection(i).Name
        Next i

        'Bubble-Sort (Sort the array in increasing order)
        For r1 = LBound(Arr) To UBound(Arr)
            rval = Arr(r1)
                For r2 = LBound(Arr) To UBound(Arr)
                    If Arr(r2) > rval Then 'Change ">" to "<" to make it decreasing
                        Arr(r1) = Arr(r2)
                        Arr(r2) = rval
                        rval = Arr(r1)
                    End If
                Next r2
        Next r1

    'Defining the PlotOrder
    For i = LBound(Arr) To UBound(Arr)
    mychart.FullSeriesCollection(Arr(i)).PlotOrder = i
    Next i

End Function

How to delete the contents of a folder?

import os, shutil
folder = '/path/to/folder'
for filename in os.listdir(folder):
    file_path = os.path.join(folder, filename)
        if os.path.isfile(file_path) or os.path.islink(file_path):
        elif os.path.isdir(file_path):
    except Exception as e:
        print('Failed to delete %s. Reason: %s' % (file_path, e))

What is the usefulness of PUT and DELETE HTTP request methods?

Although I take the risk of not being popular I say they are not useful nowadays.

I think they were well intended and useful in the past when for example DELETE told the server to delete the resource found at supplied URL and PUT (with its sibling PATCH) told the server to do update in an idempotent manner.

Things evolved and URLs became virtual (see url rewriting for example) making resources lose their initial meaning of real folder/subforder/file and so, CRUD action verbs covered by HTTP protocol methods (GET, POST, PUT/PATCH, DELETE) lost track.

Let's take an example:

  • /api/entity/list/{id} vs GET /api/entity/{id}
  • /api/entity/add/{id} vs POST /api/entity
  • /api/entity/edit/{id} vs PUT /api/entity/{id}
  • /api/entity/delete/{id} vs DELETE /api/entity/{id}

On the left side is not written the HTTP method, essentially it doesn't matter (POST and GET are enough) and on the right side appropriate HTTP methods are used.

Right side looks elegant, clean and professional. Imagine now you have to maintain a code that's been using the elegant API and you have to search where deletion call is done. You'll search for "api/entity" and among results you'll have to see which one is doing DELETE. Or even worse, you have a junior programmer which by mistake switched PUT with DELETE and as URL is the same shit happened.

In my opinion putting the action verb in the URL has advantages over using the appropriate HTTP method for that action even if it's not so elegant. If you want to see where delete call is made you just have to search for "api/entity/delete" and you'll find it straight away.

Building an API without the whole HTTP array of methods makes it easier to be consumed and maintained afterwards

converting epoch time with milliseconds to datetime

Use datetime.datetime.fromtimestamp:

>>> import datetime
>>> s = 1236472051807 / 1000.0
>>> datetime.datetime.fromtimestamp(s).strftime('%Y-%m-%d %H:%M:%S.%f')
'2009-03-08 09:27:31.807000'

%f directive is only supported by datetime.datetime.strftime, not by time.strftime.

UPDATE Alternative using %, str.format:

>>> import time
>>> s, ms = divmod(1236472051807, 1000)  # (1236472051, 807)
>>> '%s.%03d' % (time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(s)), ms)
'2009-03-08 00:27:31.807'
>>> '{}.{:03d}'.format(time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(s)), ms)
'2009-03-08 00:27:31.807'

size of struct in C

Your default alignment is probably 4 bytes. Either the 30 byte element got 32, or the structure as a whole was rounded up to the next 4 byte interval.

Find if listA contains any elements not in listB

List has Contains method that return bool. We can use that method in query.

List<int> listA = new List<int>();
List<int> listB = new List<int>();
listA.AddRange(new int[] { 1,2,3,4,5 });
listB.AddRange(new int[] { 3,5,6,7,8 });

var v = from x in listA
        where !listB.Contains(x)
        select x;

foreach (int i in v)

Python: finding an element in a list

how's this one?

def global_index(lst, test):
    return ( pair[0] for pair in zip(range(len(lst)), lst) if test(pair[1]) )


>>> global_index([1, 2, 3, 4, 5, 6], lambda x: x>3)
<generator object <genexpr> at ...>
>>> list(_)
[3, 4, 5]

Copy values from one column to another in the same table

Short answer for the code in question is:

UPDATE `table` SET test=number

Here table is the table name and it's surrounded by grave accent (aka back-ticks `) as this is MySQL convention to escape keywords (and TABLE is a keyword in that case).

BEWARE, that this is pretty dangerous query which will wipe everything in column test in every row of your table replacing it by the number (regardless of it's value)

It is more common to use WHERE clause to limit your query to only specific set of rows:

UPDATE `products` SET `in_stock` = true WHERE `supplier_id` = 10

How to take off line numbers in Vi?

write command in terminal:

vi ~/.vimrc

for set the number:
write set number

for remove number:
write set nonumber

Parsing ISO 8601 date in Javascript

datejs could parse following, you might want to try out.

Date.parse('1997-07-16T19:20:15')           // ISO 8601 Formats
Date.parse('1997-07-16T19:20:30+01:00')     // ISO 8601 with Timezone offset

Edit: Regex version

x = "2011-01-28T19:30:00EST"

MM = ["January", "February","March","April","May","June","July","August","September","October","November", "December"]

xx = x.replace(
        return MM[$2-1]+" "+$3+", "+$1+" - "+$4%12+":"+$5+(+$4>12?"PM":"AM")+" "+$6


January 28, 2011 - 7:30PM EST

Edit2: I changed my timezone to EST and now I got following

x = "2011-01-28T19:30:00-05:00"

MM = {Jan:"January", Feb:"February", Mar:"March", Apr:"April", May:"May", Jun:"June", Jul:"July", Aug:"August", Sep:"September", Oct:"October", Nov:"November", Dec:"December"}

xx = String(new Date(x)).replace(
    /\w{3} (\w{3}) (\d{2}) (\d{4}) (\d{2}):(\d{2}):[^(]+\(([A-Z]{3})\)/,
        return MM[$1]+" "+$2+", "+$3+" - "+$4%12+":"+$5+(+$4>12?"PM":"AM")+" "+$6 


January 28, 2011 - 7:30PM EST


String(new Date(x))


Fri Jan 28 2011 19:30:00 GMT-0500 (EST)

regex parts just converting above string to your required format.

January 28, 2011 - 7:30PM EST

Angular - ng: command not found

just install npm install -g @angular/cli@latest

vuetify center items into v-flex

v-flex does not have a display flex! Inspect v-flex in your browser and you will find out it is just a simple block div.

So, you should override it with display: flex in your HTML or CSS to make it work with justify-content.

Android EditText view Floating Hint in Material Design

For an easier way to use the InputTextLayout, I have created this library that cuts your XML code to less than the half, and also provides you with the ability to set an error message as well as a hint message and an easy way to do your validations.

Simply add

compile 'com.github.TeleClinic:SmartEditText:0.1.0'

Then you can do something like this:

    app:setMandatoryErrorMsg="Mandatory field"
    app:setRegexErrorMsg="Wrong email format"
    app:setRegexType="EMAIL_VALIDATION" />

    app:setMandatoryErrorMsg="Mandatory field"
    app:setRegexErrorMsg="Weak password"
    app:setRegexType="MEDIUM_PASSWORD_VALIDATION" />

    app:setRegexErrorMsg="Is that really your age :D?"
    app:setRegexString=".*\\d.*" />

Parameter binding on left joins with array in Laravel Query Builder

You don't have to bind parameters if you use query builder or eloquent ORM. However, if you use DB::raw(), ensure that you binding the parameters.

Try the following:

$array = array(1,2,3);       $query = DB::table('offers');             $query->select('id', 'business_id', 'address_id', 'title', 'details', 'value', 'total_available', 'start_date', 'end_date', 'terms', 'type', 'coupon_code', 'is_barcode_available', 'is_exclusive', 'userinformations_id', 'is_used');             $query->leftJoin('user_offer_collection', function ($join) use ($array)             {                 $join->on('user_offer_collection.offers_id', '=', '')                       ->whereIn('user_offer_collection.user_id', $array);             });       $query->get(); 

How do I install a NuGet package .nupkg file locally?

If you have a .nupkg file and just need the .dll file all you have to do is change the extension to .zip and find the lib directory.

How can I get the name of an html page in Javascript?

Use window.location.pathname to get the path of the current page's URL.

gitbash command quick reference

You should accept Mike Gossland's answer, but it can be improved a little. Try this in Git Bash:

 ls -1F /bin | grep '\*$' | grep -v '\.dll\*$' | sed 's/\*$\|\.exe//g'


List on 1 line, decorated with trailing * for executables, all files in bin. Keep only those with the trailing *s, but NOT ending with .dll*, then replace all ending asterisks or ".exe" with nothing.

This gives you a clean list of all the GitBash commands.

How to make a cross-module variable?

I use this for a couple built-in primitive functions that I felt were really missing. One example is a find function that has the same usage semantics as filter, map, reduce.

def builtin_find(f, x, d=None):
    for i in x:
        if f(i):
            return i
    return d

import __builtin__
__builtin__.find = builtin_find

Once this is run (for instance, by importing near your entry point) all your modules can use find() as though, obviously, it was built in.

find(lambda i: i < 0, [1, 3, 0, -5, -10])  # Yields -5, the first negative.

Note: You can do this, of course, with filter and another line to test for zero length, or with reduce in one sort of weird line, but I always felt it was weird.

Angular 2: Get Values of Multiple Checked Checkboxes

Here's a simple way using ngModel (final Angular 2)

<!-- my.component.html -->

<div class="form-group">
    <label for="options">Options:</label>
    <div *ngFor="let option of options">
            <input type="checkbox"

// my.component.ts

@Component({, templateUrl:'my.component.html'})

export class MyComponent {
  options = [
    {name:'OptionA', value:'1', checked:true},
    {name:'OptionB', value:'2', checked:false},
    {name:'OptionC', value:'3', checked:true}

  get selectedOptions() { // right now: ['1','3']
    return this.options
              .filter(opt => opt.checked)
              .map(opt => opt.value)

How can I render HTML from another file in a React component?

You could do it if template is a react component.


var React = require('react');

var Template = React.createClass({
    render: function(){
        return (<div>Mi HTML</div>);

module.exports = Template;


var React = require('react');
var ReactDOM = require('react-dom');
var injectTapEventPlugin = require("react-tap-event-plugin");
var Template = require('./Template');

//Needed for React Developer Tools
window.React = React;

//Needed for onTouchTap
//Can go away when react 1.0 release
//Check this repo:

var MainComponent = React.createClass({
    render: function() {

// Render the main app react component into the app div.
// For more details see:
  <MainComponent />,

And if you are using Material-UI, for compatibility use Material-UI Components, no normal inputs.

How can I plot data with confidence intervals?

Some addition to the previous answers. It is nice to regulate the density of the polygon to avoid obscuring the data points.

lm.fit2 = lm(medv~poly(lstat,2))
new.lstat = seq(min(lstat), max(lstat), length.out=100)
preds <- predict(lm.fit2, newdata = data.frame(lstat=new.lstat), interval = 'prediction')
lines(sort(lstat), fitted(lm.fit2)[order(lstat)], col='red', lwd=3) 
polygon(c(rev(new.lstat), new.lstat), c(rev(preds[ ,3]), preds[ ,2]), density=10, col = 'blue', border = NA)
lines(new.lstat, preds[ ,3], lty = 'dashed', col = 'red')
lines(new.lstat, preds[ ,2], lty = 'dashed', col = 'red')

drawing of the prediction interval in polynomial regression

Please note that you see the prediction interval on the picture, which is several times wider than the confidence interval. You can read here the detailed explanation of those two types of interval estimates.

WAMP won't turn green. And the VCRUNTIME140.dll error

As Oriol said, you need the following redistributables before installing WAMP.

From the readme.txt

BEFORE proceeding with the installation of Wampserver, you must ensure that certain elements are installed on your system, otherwise Wampserver will absolutely not run, and in addition, the installation will be faulty and you need to remove Wampserver BEFORE installing the elements that were missing.

Make sure you are "up to date" in the redistributable packages VC9, VC10, VC11, VC13 and VC14 Even if you think you are up to date, install each package as administrator and if message "Already installed", validate Repair.

The following packages (VC9, VC10, VC11) are imperatively required to Wampserver 2.4, 2.5 and 3.0, even if you use only Apache and PHP versions VC11 and VC14 is required for PHP 7 and Apache 2.4.17

org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject

JSONObject obj=(JSONObject)JSONValue.parse(content); 
JSONArray arr=(JSONArray)obj.get("units"); 
System.out.println(arr.get(1));  //this will print {"id":42,...sities ..}

@cyberz is right but explain it reverse

How to debug Angular JavaScript Code

Maybe you can use Angular Augury A Google Chrome Dev Tools extension for debugging Angular 2 and above applications.

Resizing a button

If you want to call a different size for the button inline, you would probably do it like this:

<div class="button" style="width:60px;height:100px;">This is a button</div>

Or, a better way to have different sizes (say there will be 3 standard sizes for the button) would be to have classes just for size.

For example, you would call your button like this:

<div class="button small">This is a button</div>

And in your CSS

.button.small { width: 60px; height: 100px; }

and just create classes for each size you wish to have. That way you still have the perks of using a stylesheet in case say, you want to change the size of all the small buttons at once.

Forcing label to flow inline with input that they label

What I did so that input didn't take up the whole line, and be able to place the input in a paragraph, I used a span tag and display to inline-block


        <input class="short-input" type="text" name="cluster">


span{display: inline-block;}

Convert HTML5 into standalone Android App

You can use It is the same phonegap but in very convinient wrapper

Calling stored procedure from another stored procedure SQL Server

First of all, if table2's idProduct is an identity, you cannot insert it explicitly until you set IDENTITY_INSERT on that table


before the insert.

So one of two, you modify your second stored and call it with only the parameters productName and productDescription and then get the new ID

EXEC test2 'productName', 'productDescription'

or you already have the ID of the product and you don't need to call SCOPE_IDENTITY() and can make the insert on table1 with that ID

Get a DataTable Columns DataType

What you want to use is this property:


The DataType property will set to one of the following:


DataColumn.DataType Property MSDN Reference

How to measure time in milliseconds using ANSI C?

timespec_get from C11

Returns up to nanoseconds, rounded to the resolution of the implementation.

Looks like an ANSI ripoff from POSIX' clock_gettime.

Example: a printf is done every 100ms on Ubuntu 15.10:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

static long get_nanos(void) {
    struct timespec ts;
    timespec_get(&ts, TIME_UTC);
    return (long)ts.tv_sec * 1000000000L + ts.tv_nsec;

int main(void) {
    long nanos;
    long last_nanos;
    long start;
    nanos = get_nanos();
    last_nanos = nanos;
    start = nanos;
    while (1) {
        nanos = get_nanos();
        if (nanos - last_nanos > 100000000L) {
            printf("current nanos: %ld\n", nanos - start);
            last_nanos = nanos;
    return EXIT_SUCCESS;

The C11 N1570 standard draft "The timespec_get function says":

If base is TIME_UTC, the tv_sec member is set to the number of seconds since an implementation defined epoch, truncated to a whole value and the tv_nsec member is set to the integral number of nanoseconds, rounded to the resolution of the system clock. (321)

321) Although a struct timespec object describes times with nanosecond resolution, the available resolution is system dependent and may even be greater than 1 second.

C++11 also got std::chrono::high_resolution_clock: C++ Cross-Platform High-Resolution Timer

glibc 2.21 implementation

Can be found under sysdeps/posix/timespec_get.c as:

timespec_get (struct timespec *ts, int base)
  switch (base)
    case TIME_UTC:
      if (__clock_gettime (CLOCK_REALTIME, ts) < 0)
        return 0;

      return 0;

  return base;

so clearly:

  • only TIME_UTC is currently supported

  • it forwards to __clock_gettime (CLOCK_REALTIME, ts), which is a POSIX API:

    Linux x86-64 has a clock_gettime system call.

    Note that this is not a fail-proof micro-benchmarking method because:

    • man clock_gettime says that this measure may have discontinuities if you change some system time setting while your program runs. This should be a rare event of course, and you might be able to ignore it.

    • this measures wall time, so if the scheduler decides to forget about your task, it will appear to run for longer.

    For those reasons getrusage() might be a better better POSIX benchmarking tool, despite it's lower microsecond maximum precision.

    More information at: Measure time in Linux - time vs clock vs getrusage vs clock_gettime vs gettimeofday vs timespec_get?

Round button with text and icon in flutter

You can simply use named constructors for creating different types of buttons with icons. For instance

FlatButton.icon(onPressed: null, icon: null, label: null);
RaisedButton.icon(onPressed: null, icon: null, label: null);

But if you have specfic requirements then you can always create custom button with different layouts or simply wrap a widget in GestureDetector.

connecting to mysql server on another PC in LAN

Since you have mysql on your local computer, you do not need to bother with the IP address of the machine. Just use localhost:

mysql -u user -p


mysql -hlocalhost -u user -p

If you cannot login with this, you must find out what usernames (user@host) exist in the MySQL Server locallly. Here is what you do:

Step 01) Startup mysql so that no passwords are require no passwords and denies TCP/IP connections

service mysql restart --skip-grant-tables --skip-networking

Keep in mind that standard SQL for adding users, granting and revoking privs are disabled.

Step 02) Show users and hosts

select concat(''',user,'''@''',host,'''') userhost,password from mysql.user;

Step 03) Check your password to make sure it works

select user,host from mysql.user where password=password('YourMySQLPassword');

If your password produces no output for this query, you have a bad password.

If your password produces output for this query, look at the users and hosts. If your host value is '%', your should be able to connect from anywhere. If your host is 'localhost', you should be able to connect locally.

Make user you have 'root'@'localhost' defined.

Once you have done what is needed, just restart mysql normally

service mysql restart

If you are able to connect successfully on the macbook, run this query:


USER() reports how you attempted to authenticate in MySQL

CURRENT_USER() reports how you were allowed to authenticate in MySQL

Let us know what happens !!!

UPDATE 2012-02-13 20:47 EDT

Login to the remote server and repeat Step 1-3

See if any user allows remote access (i.e, host in mysql.user is '%'). If you do not, then add 'user'@'%' to mysql.user.

How to .gitignore all files/folder in a folder, but not the folder itself?

Put this .gitignore into the folder, then git add .gitignore.


The * line tells git to ignore all files in the folder, but !.gitignore tells git to still include the .gitignore file. This way, your local repository and any other clones of the repository all get both the empty folder and the .gitignore it needs.

Edit: May be obvious but also add */ to the .gitignore to also ignore subfolders.

Android: textview hyperlink

This is my working implementation

private void showMessage()


        List<String> messages = db.getAllGCMMessages();

        for (int k = messages.size() - 1; k >= 0; --k)

            String message  =  messages.get(k).toString();
            lblMessage.append(message + "\n\n");

     Linkify.addLinks(lblMessage, Linkify.ALL);

and to change color of hyperlinks , i editted my xml for textview -


SQL Server : Transpose rows to columns

I had a slightly different requirement, whereby I had to selectively transpose columns into rows.

The table had columns:

create table tbl (ID, PreviousX, PreviousY, CurrentX, CurrentY)

I needed columns for Previous and Current, and rows for X and Y. A Cartesian product generated on a static table worked nicely, eg:

    max(case when metric='X' then PreviousX
        case when metric='Y' then PreviousY end) as Previous,
    max(case when metric='X' then CurrentX
        case when metric='Y' then CurrentY end) as Current
from tbl inner join
    /* Cartesian product - transpose by repeating row and 
    picking appropriate metric column for period */
    ( VALUES (1, 'X'), (2, 'Y')) AS x (sort, metric) ON 1=1
group by ID
order by ID, sort

How to select only the first rows for each unique value of a column?

This will give you one row of each duplicate row. It will also give you the bit-type columns, and it works at least in MS Sql Server.

(select cname, address 
from (
  select cname,address, rn=row_number() over (partition by cname order by cname) 
  from customeraddresses  
) x 
where rn = 1) order by cname

If you want to find all the duplicates instead, just change the rn= 1 to rn > 1. Hope this helps

What is the exact meaning of Git Bash?

I think the question asker is (was) thinking that git bash is a command like git init or git checkout. Git bash is not a command, it is an interface. I will also assume the asker is not a linux user because bash is very popular the unix/linux world. The name "bash" is an acronym for "Bourne Again SHell". Bash is a text-only command interface that has features which allow automated scripts to be run. A good analogy would be to compare bash to the new PowerShell interface in Windows7/8. A poor analogy (but one likely to be more readily understood by more people) is the combination of the command prompt and .BAT (batch) command files from the days of DOS and early versions of Windows.


How to copy Java Collections list

The answer by Stephen Katulka (accepted answer) is wrong (the second part). It explains that Collections.copy(b, a); does a deep copy, which it does not. Both, new ArrayList(a); and Collections.copy(b, a); only do a shallow copy. The difference is, that the constructor allocates new memory, and copy(...) does not, which makes it suitable in cases where you can reuse arrays, as it has a performance advantage there.

The Java standard API tries to discourage the use of deep copies, as it would be bad if new coders would use this on a regular basis, which may also be one of the reason why clone() is not public by default.

The source code for Collections.copy(...) can be seen on line 552 at:

If you need a deep copy, you have to iterate over the items manually, using a for loop and clone() on each object.

Validate date in dd/mm/yyyy format using JQuery Validate

This works fine for me.

$(document).ready(function () {
       $('#btn_move').click( function(){
           var dateformat = /^(0?[1-9]|[12][0-9]|3[01])[\/\-](0?[1-9]|1[012])[\/\-]\d{4}$/;
           var Val_date=$('#txt_date').val();
              var seperator1 = Val_date.split('/');
              var seperator2 = Val_date.split('-');

              if (seperator1.length>1)
                  var splitdate = Val_date.split('/');
              else if (seperator2.length>1)
                  var splitdate = Val_date.split('-');
              var dd = parseInt(splitdate[0]);
              var mm  = parseInt(splitdate[1]);
              var yy = parseInt(splitdate[2]);
              var ListofDays = [31,28,31,30,31,30,31,31,30,31,30,31];
              if (mm==1 || mm>2)
                  if (dd>ListofDays[mm-1])
                      alert('Invalid date format!');
                      return false;
              if (mm==2)
                  var lyear = false;
                  if ( (!(yy % 4) && yy % 100) || !(yy % 400))
                      lyear = true;
                  if ((lyear==false) && (dd>=29))
                      alert('Invalid date format!');
                      return false;
                  if ((lyear==true) && (dd>29))
                      alert('Invalid date format!');
                      return false;
              alert("Invalid date format!");

              return false;

Set Memory Limit in htaccess

In your .htaccess you can add:

PHP 5.x

<IfModule mod_php5.c>
    php_value memory_limit 64M

PHP 7.x

<IfModule mod_php7.c>
    php_value memory_limit 64M

If page breaks again, then you are using PHP as mod_php in apache, but error is due to something else.

If page does not break, then you are using PHP as CGI module and therefore cannot use php values - in the link I've provided might be solution but I'm not sure you will be able to apply it.


How to filter rows containing a string pattern from a Pandas dataframe

>>> mask = df['ids'].str.contains('ball')    
>>> mask
0     True
1     True
2    False
3     True
Name: ids, dtype: bool

>>> df[mask]
     ids  vals
0  aball     1
1  bball     2
3  fball     4

How to increase the max connections in postgres?

change max_connections variable in postgresql.conf file located in /var/lib/pgsql/data or /usr/local/pgsql/data/

How to add a margin to a table row <tr>

This isn't going to be exactly perfect though I was happy to discover that you can control the horizontal and vertical border-spacing separately:

 border-collapse: separate;
 border-spacing: 0 8px;

How should I read a file line-by-line in Python?


with open('filename.txt') as fp:
    for line in fp:
        print line

is the way to go.

It is not more verbose. It is more safe.

SQL QUERY replace NULL value in a row with a value from the previous known value

If you're looking for a solution for Redshift, this will work with the frame clause:

SELECT date, 
       last_value(columnName ignore nulls) 
                   over (order by date
                         rows between unbounded preceding and current row) as columnName 
 from tbl

How to concatenate variables into SQL strings

You could make use of Prepared Stements like this.

set @query = concat( "select name from " );
set @query = concat( "table_name"," [where condition] " );

prepare stmt from @like_q;
execute stmt;

Is it possible to open developer tools console in Chrome on Android phone?

Kiwi Browser is mobile Chromium and allows installing extensions. Install Kiwi and then install "Mini JS console" Chrome extension(just search in Google and install from Chrome extensions website, uBlock also works ;). It will become available in Kiwi menu at the bottom and will show the console output for the current page.

Dynamic require in RequireJS, getting "Module name has not been loaded yet for context" error?

Answering to myself. From the RequireJS website:

define(['require'], function (require) {
    var namedModule = require('name');

This fails because requirejs needs to be sure to load and execute all dependencies before calling the factory function above. [...] So, either do not pass in the dependency array, or if using the dependency array, list all the dependencies in it.

My solution:

// Modules configuration (modules that will be used as Jade helpers)
define(function () {
    return {
        'moment':   'path/to/moment',
        'filesize': 'path/to/filesize',
        '_':        'path/to/lodash',
        '_s':       'path/to/underscore.string'

The loader:

define(['jade', 'lodash', 'config'], function (Jade, _, Config) {
    var deps;

    // Dynamic require
    require(_.values(Config), function () {
        deps = _.object(_.keys(Config), arguments);

        // Use deps...

Output PowerShell variables to a text file

You can concatenate an array of values together using PowerShell's `-join' operator. Here is an example:

$FilePath = '{0}\temp\scripts\pshell\dump.txt' -f $env:SystemDrive;

$Computer = 'pc1';
$Speed = 9001;
$RegCheck = $true;

$Computer,$Speed,$RegCheck -join ',' | Out-File -FilePath $FilePath -Append -Width 200;



Why isn't ProjectName-Prefix.pch created automatically in Xcode 6?

Use :

$(PROJECT_DIR)/Project name/PrefixHeader.pch

SQL Server 2008 Windows Auth Login Error: The login is from an untrusted domain

in order to enable windows authentication both computers need to be in the same domain. in order to allow managment studios to pass the current credentials and authenticate in the sql box


Database tables

To demonstrate how the USING and ON clauses work, let's assume we have the following post and post_comment database tables, which form a one-to-many table relationship via the post_id Foreign Key column in the post_comment table referencing the post_id Primary Key column in the post table:

SQL USING vs ON clauses table relationship

The parent post table has 3 rows:

| post_id | title     |
| 1       | Java      |
| 2       | Hibernate |
| 3       | JPA       |

and the post_comment child table has the 3 records:

| post_comment_id | review    | post_id |
| 1               | Good      | 1       |
| 2               | Excellent | 1       |
| 3               | Awesome   | 2       |

The JOIN ON clause using a custom projection

Traditionally, when writing an INNER JOIN or LEFT JOIN query, we happen to use the ON clause to define the join condition.

For example, to get the comments along with their associated post title and identifier, we can use the following SQL projection query:

FROM post
INNER JOIN post_comment ON post.post_id = post_comment.post_id
ORDER BY post.post_id, post_comment_id

And, we get back the following result set:

| post_id | title     | review    |
| 1       | Java      | Good      |
| 1       | Java      | Excellent |
| 2       | Hibernate | Awesome   |

The JOIN USING clause using a custom projection

When the Foreign Key column and the column it references have the same name, we can use the USING clause, like in the following example:

FROM post
INNER JOIN post_comment USING(post_id)
ORDER BY post_id, post_comment_id

And, the result set for this particular query is identical to the previous SQL query that used the ON clause:

| post_id | title     | review    |
| 1       | Java      | Good      |
| 1       | Java      | Excellent |
| 2       | Hibernate | Awesome   |

The USING clause works for Oracle, PostgreSQL, MySQL, and MariaDB. SQL Server doesn't support the USING clause, so you need to use the ON clause instead.

The USING clause can be used with INNER, LEFT, RIGHT, and FULL JOIN statements.

SQL JOIN ON clause with SELECT *

Now, if we change the previous ON clause query to select all columns using SELECT *:

FROM post
INNER JOIN post_comment ON post.post_id = post_comment.post_id
ORDER BY post.post_id, post_comment_id

We are going to get the following result set:

| post_id | title     | post_comment_id | review    | post_id |
| 1       | Java      | 1               | Good      | 1       |
| 1       | Java      | 2               | Excellent | 1       |
| 2       | Hibernate | 3               | Awesome   | 2       |

As you can see, the post_id is duplicated because both the post and post_comment tables contain a post_id column.


On the other hand, if we run a SELECT * query that features the USING clause for the JOIN condition:

FROM post
INNER JOIN post_comment USING(post_id)
ORDER BY post_id, post_comment_id

We will get the following result set:

| post_id | title     | post_comment_id | review    |
| 1       | Java      | 1               | Good      |
| 1       | Java      | 2               | Excellent |
| 2       | Hibernate | 3               | Awesome   |

You can see that this time, the post_id column is deduplicated, so there is a single post_id column being included in the result set.


If the database schema is designed so that Foreign Key column names match the columns they reference, and the JOIN conditions only check if the Foreign Key column value is equal to the value of its mirroring column in the other table, then you can employ the USING clause.

Otherwise, if the Foreign Key column name differs from the referencing column or you want to include a more complex join condition, then you should use the ON clause instead.

how to save canvas as png image?

I really like Tovask's answer but it doesn't work due to the function having the name download (this answer explains why). I also don't see the point in replacing "data:image/..." with "data:application/...".

The following code has been tested in Chrome and Firefox and seems to work fine in both.


function prepDownload(a, canvas, name) { = name
    a.href = canvas.toDataURL()


<a href="#" onclick="prepDownload(this, document.getElementById('canvasId'), 'imgName.png')">Download</a>
<canvas id="canvasId"></canvas>

How do I calculate the date in JavaScript three months prior to today?

var d = new Date();
d.setMonth(d.getMonth() - 3);

This works for January. Run this snippet:

var d = new Date("January 14, 2012");_x000D_
d.setMonth(d.getMonth() - 3);_x000D_

There are some caveats...

A month is a curious thing. How do you define 1 month? 30 days? Most people will say that one month ago means the same day of the month on the previous month citation needed. But more than half the time, that is 31 days ago, not 30. And if today is the 31st of the month (and it isn't August or Decemeber), that day of the month doesn't exist in the previous month.

Interestingly, Google agrees with JavaScript if you ask it what day is one month before another day:

Google search result for 'one month before March 31st' shows 'March 3rd'

It also says that one month is 30.4167 days long: Google search result for 'one month in days' shows '30.4167'

So, is one month before March 31st the same day as one month before March 28th, 3 days earlier? This all depends on what you mean by "one month before". Go have a conversation with your product owner.

If you want to do like momentjs does, and correct these last day of the month errors by moving to the last day of the month, you can do something like this:

const d = new Date("March 31, 2019");_x000D_
const month = d.getMonth();_x000D_
d.setMonth(d.getMonth() - 1);_x000D_
while (d.getMonth() === month) {_x000D_
    d.setDate(d.getDate() - 1);_x000D_

If your requirements are more complicated than that, use some math and write some code. You are a developer! You don't have to install a library! You don't have to copy and paste from stackoverflow! You can develop the code yourself to do precisely what you need!

Make footer stick to bottom of page using Twitter Bootstrap

just add the class navbar-fixed-bottom to your footer.

<div class="footer navbar-fixed-bottom">

Update for Bootstrap 4 -

as mentioned by Sara Tibbetts - class is fixed-bottom

<div class="footer fixed-bottom">

Eclipse/Maven error: "No compiler is provided in this environment"

Go to Window ? Preferences ? Java ? Installed JREs.

And see if there is an entry pointing to your JDK path, and if not, click on Edit button and put the path you configured your JAVA_HOME environment.

Linking static libraries to other static libraries

Note before you read the rest: The shell script shown here is certainly not safe to use and well tested. Use at your own risk!

I wrote a bash script to accomplish that task. Suppose your library is lib1 and the one you need to include some symbols from is lib2. The script now runs in a loop, where it first checks which undefined symbols from lib1 can be found in lib2. It then extracts the corresponding object files from lib2 with ar, renames them a bit, and puts them into lib1. Now there may be more missing symbols, because the stuff you included from lib2 needs other stuff from lib2, which we haven't included yet, so the loop needs to run again. If after some passes of the loop there are no changes anymore, i.e. no object files from lib2 added to lib1, the loop can stop.

Note, that the included symbols are still reported as undefined by nm, so I'm keeping track of the object files, that were added to lib1, themselves, in order to determine whether the loop can be stopped.

#! /bin/bash


if [ ! -e $lib1.backup ]; then
    echo backing up
    cp $lib1 $lib1.backup


new_tmp_file() {
    remove_later="$remove_later $file"
    eval $1=$file
remove_tmp_files() {
    rm $remove_later
trap remove_tmp_files EXIT

find_symbols() {
    nm $1 $2 | cut -c20- | sort | uniq 

new_tmp_file lib2symbols
new_tmp_file currsymbols

nm $lib2 -s --defined-only > $lib2symbols

while true; do
    echo "Starting pass #$pass"
    find_symbols $curr "--undefined-only" > $currsymbols
    for sym in $(cat $currsymbols); do
        for obj in $(egrep "^$sym in .*\.o" $lib2symbols | cut -d" " -f3); do
            echo "  Found $sym in $obj."
            if [ -e "$prefix$obj" ]; then continue; fi
            echo "    -> Adding $obj to $lib1"
            ar x $lib2 $obj
            mv $obj "$prefix$obj"
            ar -r -s $lib1 "$prefix$obj"
            remove_later="$remove_later $prefix$obj"
    echo "Found $changed changes in pass #$pass"

    if [[ $changed == 0 ]]; then break; fi

I named that script libcomp, so you can call it then e.g. with

./libcomp libmylib.a libwhatever.a

where libwhatever is where you want to include symbols from. However, I think it's safest to copy everything into a separate directory first. I wouldn't trust my script so much (however, it worked for me; I could include libgsl.a into my numerics library with that and leave out that -lgsl compiler switch).

How to reload the current state?

That would be the final solution. (inspired by @Hollan_Risley's post)

'use strict';


.config(function($provide) {
    $provide.decorator('$state', function($delegate, $stateParams) {
        $delegate.forceReload = function() {
            return $delegate.go($delegate.current, $stateParams, {
                reload: true,
                inherit: false,
                notify: true
        return $delegate;

Now, whenever you need to reload, simply call:


Calculating the distance between 2 points

Given points (X1,Y1) and (X2,Y2) then:

dX = X1 - X2;
dY = Y1 - Y2;

if (dX*dX + dY*dY > (5*5))
    //your code

How does a PreparedStatement avoid or prevent SQL injection?

SQL injection: when user has the chance to input something that could be part of the sql statement

For example:

String query = “INSERT INTO students VALUES(‘” + user + “‘)”

when user input “Robert’); DROP TABLE students; –” as the input, it causes SQL injection

How prepared statement prevents this?

String query = “INSERT INTO students VALUES(‘” + “:name” + “‘)”

parameters.addValue(“name”, user);

=> when user input again “Robert’); DROP TABLE students; –“, the input string is precompiled on the driver as literal values and I guess it may be casted like:

CAST(‘Robert’); DROP TABLE students; –‘ AS varchar(30))

So at the end, the string will be literally inserted as the name to the table.

Can't connect to local MySQL server through socket '/tmp/mysql.sock

Run the below cmd in terminal


enter image description here

Then restart the machine to take effect. It works!!

Bizarre Error in Chrome Developer Console - Failed to load resource: net::ERR_CACHE_MISS

Check for the presence of words like "ad", "banner" or "popup" within your file. I removed these and it worked. Based on this post here: Failed to load resource under Chrome it seems like Ad Block Plus was the culprit in my case.

How do I test axios in Jest?

I've done this with nock, like so:

import nock from 'nock'
import axios from 'axios'
import httpAdapter from 'axios/lib/adapters/http'

axios.defaults.adapter = httpAdapter

describe('foo', () => {
    it('bar', () => {
            .reply(200, 'some payload')

        // test...

Avoid trailing zeroes in printf()

Some of the highly voted solutions suggest the %g conversion specifier of printf. This is wrong because there are cases where %g will produce scientific notation. Other solutions use math to print the desired number of decimal digits.

I think the easiest solution is to use sprintf with the %f conversion specifier and to manually remove trailing zeros and possibly a decimal point from the result. Here's a C99 solution:

#include <stdio.h>
#include <stdlib.h>

format_double(double d) {
    int size = snprintf(NULL, 0, "%.3f", d);
    char *str = malloc(size + 1);
    snprintf(str, size + 1, "%.3f", d);

    for (int i = size - 1, end = size; i >= 0; i--) {
        if (str[i] == '0') {
            if (end == i + 1) {
                end = i;
        else if (str[i] == '.') {
            if (end == i + 1) {
                end = i;
            str[end] = '\0';

    return str;

Note that the characters used for digits and the decimal separator depend on the current locale. The code above assumes a C or US English locale.

How to write a multiline Jinja statement

According to the documentation: you may use multi-line statements as long as the code has parens/brackets around it. Example:

{% if ( (foo == 'foo' or bar == 'bar') and 
        (fooo == 'fooo' or baar == 'baar') ) %}
    <li>some text</li>
{% endif %}

Edit: Using line_statement_prefix = '#'* the code would look like this:

# if ( (foo == 'foo' or bar == 'bar') and 
       (fooo == 'fooo' or baar == 'baar') )
    <li>some text</li>
# endif

*Here's an example of how you'd specify the line_statement_prefix in the Environment:

from jinja2 import Environment, PackageLoader, select_autoescape
env = Environment(
    loader=PackageLoader('yourapplication', 'templates'),
    autoescape=select_autoescape(['html', 'xml']),

Or using Flask:

from flask import Flask
app = Flask(__name__, instance_relative_config=True, static_folder='static')
app.jinja_env.filters['zip'] = zip
app.jinja_env.line_statement_prefix = '#'

Change image size with JavaScript

Once you have a reference to your image, you can set its height and width like so:

var yourImg = document.getElementById('yourImgId');
if(yourImg && { = '100px'; = '200px';

In the html, it would look like this:

<img src="src/to/your/img.jpg" id="yourImgId" alt="alt tags are key!"/>

How do I create an .exe for a Java program?

If you really want an exe Excelsior JET is a professional level product that compiles to native code:

You can also look at JSMooth:

And if your application is compatible with its compatible with AWT/Apache classpath then GCJ compiles to native exe.

How to save a dictionary to a file?

file_name = open("data.json", "w")
json.dump(test_response, file_name)

or use context manager, which is better:

with open("data.json", "w") as file_name:
    json.dump(test_response, file_name)

error: expected class-name before ‘{’ token

If you forward-declare Flight and Landing in Event.h, then you should be fixed.

Remember to #include "Flight.h" and #include "Landing.h" in your implementation file for Event.

The general rule of thumb is: if you derive from it, or compose from it, or use it by value, the compiler must know its full definition at the time of declaration. If you compose from a pointer-to-it, the compiler will know how big a pointer is. Similarly, if you pass a reference to it, the compiler will know how big the reference is, too.

How to duplicate a git repository? (without forking)

I have noticed some of the other answers here use a bare clone and then mirror push to the new repository, however this does not work for me and when I open the new repository after that, the files look mixed up and not as I expect.

Here is a solution that definitely works for copying the files, although it does not preserve the original repository's revision history.

  1. git clone the repository onto your local machine.
  2. cd into the project directory and then run rm -rf .git to remove all the old git metadata including commit history, etc.
  3. Initialize a fresh git repository by running git init.
  4. Run git add . ; git commit -am "Initial commit" - Of course you can call this commit what you want.
  5. Set the origin to your new repository git remote add origin (replace the url with the url to your new repository)
  6. Push it to your new repository with git push origin master.

Child inside parent with min-height: 100% not inheriting height

thought I would share this, as I didnt see this anywhere, and is what I used to fix my solution.

SOLUTION: min-height: inherit;

I had a parent with a specified min height, and I needed a child to also be that height.

.parent {_x000D_
  min-height: 300px;_x000D_
  background-color: rgba(255,255,0,0.5); //yellow_x000D_
.child {_x000D_
  min-height: inherit;_x000D_
  background-color: rgba(0,255,0,0.5); //blue_x000D_
p {_x000D_
  padding: 20px;_x000D_
  color: red;_x000D_
  font-family: sans-serif;_x000D_
  font-weight: bold;_x000D_
  text-align: center;_x000D_
<div class="parent">_x000D_
  <div class="child">_x000D_
    <p>Yellow + Blue = Green :)</p>_x000D_

This way the child now acts as height 100% of the min-height.

I hope some people find this useful :)

Adding form action in html in laravel

Your form is also missing '{{csrf_field()}}'

Does Hive have a String split function?

Just a clarification on the answer given by Bkkbrad.

I tried this suggestion and it did not work for me.

For example,






produced the desired result:


Including the metacharacter '|' inside the square brackets causes it to be interpreted literally, as intended, rather than as a metacharacter.

For elaboration of this behaviour of regexp, see:

Converting string to date in mongodb

I had some strings in the MongoDB Stored wich had to be reformated to a proper and valid dateTime field in the mongodb.

here is my code for the special date format: "2014-03-12T09:14:19.5303017+01:00"

but you can easyly take this idea and write your own regex to parse the date formats:

// format: "2014-03-12T09:14:19.5303017+01:00"
var myregexp = /(....)-(..)-(..)T(..):(..):(..)\.(.+)([\+-])(..)/;

db.Product.find().forEach(function(doc) { 
   var matches = myregexp.exec(doc.metadata.insertTime);

   if myregexp.test(doc.metadata.insertTime)) {
       var offset = matches[9] * (matches[8] == "+" ? 1 : -1);
       var hours = matches[4]-(-offset)+1
       var date = new Date(matches[1], matches[2]-1, matches[3],hours, matches[5], matches[6], matches[7] / 10000.0)
       db.Product.update({_id : doc._id}, {$set : {"metadata.insertTime" : date}})
       print("succsessfully updated");
    } else {
        print("not updated");

How to run Node.js as a background process and never die?

another solution disown the job

$ nohup node server.js &
[1] 1711
$ disown -h %1

Error Installing Homebrew - Brew Command Not Found

The warning is telling you what is wrong. The problem is that brew is kept in /usr/local/bin

So, you can try /usr/local/bin/brew doctor

To fix it permanently alter your bash profile (.bashrc or .profile in your home directory) and add the following line:

export PATH=/usr/local/bin:$PATH

Syntax for a single-line Bash infinite while loop

You can also make use of until command:

until ((0)); do foo; sleep 2; done

Note that in contrast to while, until would execute the commands inside the loop as long as the test condition has an exit status which is not zero.

Using a while loop:

while read i; do foo; sleep 2; done < /dev/urandom

Using a for loop:

for ((;;)); do foo; sleep 2; done

Another way using until:

until [ ]; do foo; sleep 2; done

Push item to associative array in PHP

If $new_input may contain more than just a 'name' element you may want to use array_merge.

$new_input = array('name'=>array(), 'details'=>array());
$new_input['name'] = array('type'=>'text', 'label'=>'First name'...);
$options['inputs'] = array_merge($options['inputs'], $new_input);

What is it exactly a BLOB in a DBMS context

They are binary large objects, you can use them to store binary data such as images or serialized objects among other things.

ES6 modules in the browser: Uncaught SyntaxError: Unexpected token import

Many modern browsers now support ES6 modules. As long as you import your scripts (including the entrypoint to your application) using <script type="module" src="..."> it will work.

Take a look at for more details:

Is it possible to interactively delete matching search pattern in Vim?

There are 3 ways I can think of:

The way that is easiest to explain is

:%s/phrase to delete//gc

but you can also (personally I use this second one more often) do a regular search for the phrase to delete

/phrase to delete

Vim will take you to the beginning of the next occurrence of the phrase.

Go into insert mode (hit i) and use the Delete key to remove the phrase.

Hit escape when you have deleted all of the phrase.

Now that you have done this one time, you can hit n to go to the next occurrence of the phrase and then hit the dot/period "." key to perform the delete action you just performed

Continue hitting n and dot until you are done.

Lastly you can do a search for the phrase to delete (like in second method) but this time, instead of going into insert mode, you

Count the number of characters you want to delete

Type that number in (with number keys)

Hit the x key - characters should get deleted

Continue through with n and dot like in the second method.

PS - And if you didn't know already you can do a capital n to move backwards through the search matches.

How to escape strings in SQL Server using PHP?

For the conversion to get the hexadecimal values in SQL back into ASCII, here is the solution I got on this (using the function from user chaos to encode into hexadecimal)

function hexEncode($data) {
        return $data;
    $unpacked = unpack('H*hex', $data);
    return '0x' . $unpacked['hex'];

function hexDecode($hex) {
    $str = '';
    for ($i=0; $i<strlen($hex); $i += 2)
        $str .= chr(hexdec(substr($hex, $i, 2)));
    return $str;

$stringHex = hexEncode('Test String');
$stringAscii = hexDecode($stringHex);

.NET End vs Form.Close() vs Application.Exit Cleaner way to close one's app

Application.Exit() kills your application but there are some instances that it won't close the application.

End is better than Application.Exit().

Is there a way to return a list of all the image file names from a folder using only Javascript?

IMHO, Edizkan Adil Ata's idea is actually the most proper way. It extracts the URLs of anchor tags and puts them in a different tag. And if you don't want to let the anchors being seen by the page visitor then just .hide() them all with JQuery or display: none; in CSS.

Also you can perform prefetching, like this:

<link rel="prefetch" href="imagefolder/clouds.jpg" />

That way you don't have to hide it and still can extract the path to the image.

return value after a promise

Use a pattern along these lines:

function getValue(file) {
  return lookupValue(file);

getValue('myFile.txt').then(function(res) {
  // do whatever with res here

(although this is a bit redundant, I'm sure your actual code is more complicated)

How do I convert a column of text URLs into active hyperlinks in Excel?

For me I just copied the entire column which has the URLs in text format into another application (say Evernote), and when they were pasted there they became links, and then I just copied them back into Excel.

The only thing here is you need to make sure the data you copy back lines up with the rest of the columns.

Getting "type or namespace name could not be found" but everything seems ok?

You might also try eliminating the code you think you're having problems with and seeing if it compiles with no references to that code. If not, fix things until it compiles again, and then work your suspected problem code back in. Sometimes I get strange errors about classes or methods that I know are correct when the compiler doesn't like something else. Once I fix the thing that it's really getting hung up on, these 'phantom' errors disappear.

C# - Substring: index and length must refer to a location within the string

Your mistake is the parameters to Substring. The first parameter should be the start index and the second should be the length or offset from the startindex.

string newString = url.Substring(18, 7);

If the length of the substring can vary you need to calculate the length.

Something in the direction of (url.Length - 18) - 4 (or url.Length - 22)

In the end it will look something like this

string newString = url.Substring(18, url.Length - 22);

How can I create a unique constraint on my column (SQL Server 2008 R2)?

One thing not clearly covered is that microsoft sql is creating in the background an unique index for the added constraint

create table Customer ( id int primary key identity (1,1) , name nvarchar(128) ) 

--Commands completed successfully.

sp_help Customer

---> index
--index_name    index_description   index_keys
--PK__Customer__3213E83FCC4A1DFA    clustered, unique, primary key located on PRIMARY   id

---> constraint
--constraint_type   constraint_name delete_action   update_action   status_enabled  status_for_replication  constraint_keys
--PRIMARY KEY (clustered)   PK__Customer__3213E83FCC4A1DFA  (n/a)   (n/a)   (n/a)   (n/a)   id

---- now adding the unique constraint


-- Commands completed successfully.

sp_help Customer

---> index
---index_name   index_description   index_keys
---PK__Customer__3213E83FCC4A1DFA   clustered, unique, primary key located on PRIMARY   id
---U_Name   nonclustered, unique, unique key located on PRIMARY name

---> constraint
---constraint_type  constraint_name delete_action   update_action   status_enabled  status_for_replication  constraint_keys
---PRIMARY KEY (clustered)  PK__Customer__3213E83FCC4A1DFA  (n/a)   (n/a)   (n/a)   (n/a)   id
---UNIQUE (non-clustered)   U_Name  (n/a)   (n/a)   (n/a)   (n/a)   name

as you can see , there is a new constraint and a new index U_Name

How do I dispatch_sync, dispatch_async, dispatch_after, etc in Swift 3, Swift 4, and beyond?

Swift 5.2, 4 and later

Main and Background Queues

let main = DispatchQueue.main
let background =
let helper = DispatchQueue(label: "another_thread") 

Working with async and sync threads!

 background.async { //async tasks here } 
 background.sync { //sync tasks here } 

Async threads will work along with the main thread.

Sync threads will block the main thread while executing.

Objective-C and Swift URL encoding

This is not my solution. Someone else wrote in stackoverflow but I have forgotten how.

Somehow this solution works "well". It handles diacritic, chinese characters, and pretty much anything else.

- (NSString *) URLEncodedString {
    NSMutableString * output = [NSMutableString string];
    const char * source = [self UTF8String];
    int sourceLen = strlen(source);
    for (int i = 0; i < sourceLen; ++i) {
        const unsigned char thisChar = (const unsigned char)source[i];
        if (false && thisChar == ' '){
            [output appendString:@"+"];
        } else if (thisChar == '.' || thisChar == '-' || thisChar == '_' || thisChar == '~' ||
                   (thisChar >= 'a' && thisChar <= 'z') ||
                   (thisChar >= 'A' && thisChar <= 'Z') ||
                   (thisChar >= '0' && thisChar <= '9')) {
            [output appendFormat:@"%c", thisChar];
        } else {
            [output appendFormat:@"%%%02X", thisChar];
    return output;

If someone would tell me who wrote this code, I'll really appreciate it. Basically he has some explanation why this encoded string will decode exactly as it wish.

I modified his solution a little. I like space to be represented with %20 rather than +. That's all.

SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

Changing the data type to text helped dataType: 'text'

I have check with JSONlint and my json format was proper. Still it was throwing error when I set dataType: 'json'

JSON Data: {"eventinvite":1,"groupcount":8,"totalMessagesUnread":0,"unreadmessages":{"378":0,"379":0,"380":0,"385":0,"390":0,"393":0,"413":0,"418":0}} 

CURRENT_DATE/CURDATE() not working as default DATE value

Currently from MySQL 8 you can set the following to a DATE column:

In MySQL Workbench, in the Default field next to the column, write: (curdate())

If you put just curdate() it will fail. You need the extra ( and ) at the beginning and end.

How to conclude your merge of a file?

I had the same error and i did followed article found on google solves my issue. You have not concluded your merge

Can't push to remote branch, cannot be resolved to branch

I was having this issue as well, and it was driving me crazy. I had something like feature/name but git branch -a showed me FEATURE/name. Renaming the branch, deleting and recreating it, nothing worked. What finally fixed it:

Go into .git/refs/heads

You'll see a FEATURE folder. Rename it to feature.

Space between two divs

DIVs inherently lack any useful meaning, other than to divide, of course.

Best course of action would be to add a meaningful class name to them, and style their individual margins in CSS.

<h1>Important Title</h1>
<div class="testimonials">...</div>
<div class="footer">...</div>

h1 {margin-bottom: 0.1em;}
div.testimonials {margin-bottom: 0.2em;}
div.footer {margin-bottom: 0;}

Android ADB device offline, can't issue commands

I can't stress that switching USB ports is key. Often front panel USB ports can be defective.

jquery clear input default value

$(document).ready(function() {
//clear on focus
$('.input').focus(function() {
   //clear when submitted
$('.button').click(function() {


How to Convert datetime value to yyyymmddhhmmss in SQL server?

SELECT REPLACE(REPLACE(REPLACE(CONVERT(VARCHAR(19), CONVERT(DATETIME, getdate(), 112), 126), '-', ''), 'T', ''), ':', '') 

Headers and client library minor version mismatch

My hosting company told me to fix this by deactivating "mysqli" and activating "nd_mysqli" in the php extensions.

The error is gone, but I don't have the knowledge to understand if this is the right method to fix this.

Entity framework linq query Include() multiple children entities

How do you construct a LINQ to Entities query to load child objects directly, instead of calling a Reference property or Load()

There is no other way - except implementing lazy loading.

Or manual loading....

myobj = context.MyObjects.First();

catching stdout in realtime from subprocess

I've noticed that there is no mention of using a temporary file as intermediate. The following gets around the buffering issues by outputting to a temporary file and allows you to parse the data coming from rsync without connecting to a pty. I tested the following on a linux box, and the output of rsync tends to differ across platforms, so the regular expressions to parse the output may vary:

import subprocess, time, tempfile, re

pipe_output, file_name = tempfile.TemporaryFile()
cmd = ["rsync", "-vaz", "-P", "/src/" ,"/dest"]

p = subprocess.Popen(cmd, stdout=pipe_output, 
while p.poll() is None:
    # p.poll() returns None while the program is still running
    # sleep for 1 second
    last_line =  open(file_name).readlines()
    # it's possible that it hasn't output yet, so continue
    if len(last_line) == 0: continue
    last_line = last_line[-1]
    # Matching to "[bytes downloaded]  number%  [speed] number:number:number"
    match_it = re.match(".* ([0-9]*)%.* ([0-9]*:[0-9]*:[0-9]*).*", last_line)
    if not match_it: continue
    # in this case, the percentage is stored in, 
    # time in  We could do something with it here...

jQuery Ajax requests are getting cancelled without being sent

In my case I was having type='submit' so when I was submitting the form the page was reloading before the ajax hit going so a simple solution was to have type="button". If you don't specify a type it's submit by default so you've gotta specify type="button"

type='submit' => type='button'


No type => type='button'

Or if you don't want to change the type or submit the form on click you can e.preventDefault() as the very first thing e.

$( "button" ).click(function( event ) {
  // AJAX Call here

How to plot two histograms together in R?

Here is an example of how you can do it in "classic" R graphics:

## generate some random data
carrotLengths <- rnorm(1000,15,5)
cucumberLengths <- rnorm(200,20,7)
## calculate the histograms - don't plot yet
histCarrot <- hist(carrotLengths,plot = FALSE)
histCucumber <- hist(cucumberLengths,plot = FALSE)
## calculate the range of the graph
xlim <- range(histCucumber$breaks,histCarrot$breaks)
ylim <- range(0,histCucumber$density,
## plot the first graph
plot(histCarrot,xlim = xlim, ylim = ylim,
     col = rgb(1,0,0,0.4),xlab = 'Lengths',
     freq = FALSE, ## relative, not absolute frequency
     main = 'Distribution of carrots and cucumbers')
## plot the second graph on top of this
opar <- par(new = FALSE)
plot(histCucumber,xlim = xlim, ylim = ylim,
     xaxt = 'n', yaxt = 'n', ## don't add axes
     col = rgb(0,0,1,0.4), add = TRUE,
     freq = FALSE) ## relative, not absolute frequency
## add a legend in the corner
       fill = rgb(1:0,0,0:1,0.4), bty = 'n',
       border = NA)

The only issue with this is that it looks much better if the histogram breaks are aligned, which may have to be done manually (in the arguments passed to hist).

AngularJS ng-click to go to another page (with Ionic framework)

If you simply want to go to another page, then what you might need is a link that looks like a button with a href like so:

<a href="/#/somepage.html" class="button">Back to Listings</a>

Hope this helps.

Is "delete this" allowed in C++?

One of the reasons that C++ was designed was to make it easy to reuse code. In general, C++ should be written so that it works whether the class is instantiated on the heap, in an array, or on the stack. "Delete this" is a very bad coding practice because it will only work if a single instance is defined on the heap; and there had better not be another delete statement, which is typically used by most developers to clean up the heap. Doing this also assumes that no maintenance programmer in the future will cure a falsely perceived memory leak by adding a delete statement.

Even if you know in advance that your current plan is to only allocate a single instance on the heap, what if some happy-go-lucky developer comes along in the future and decides to create an instance on the stack? Or, what if he cuts and pastes certain portions of the class to a new class that he intends to use on the stack? When the code reaches "delete this" it will go off and delete it, but then when the object goes out of scope, it will call the destructor. The destructor will then try to delete it again and then you are hosed. In the past, doing something like this would screw up not only the program but the operating system and the computer would need to be rebooted. In any case, this is highly NOT recommended and should almost always be avoided. I would have to be desperate, seriously plastered, or really hate the company I worked for to write code that did this.

Bootstrap 3 dropdown select

We just switched our site to bootstrap 3 and we have a bunch of forms...wasn't fun but once you get the hang it's not too bad.

Is this what you are looking for? Demo Here

<div class="form-group">
  <label class="control-label col-sm-offset-2 col-sm-2" for="company">Company</label>
  <div class="col-sm-6 col-md-4">
    <select id="company" class="form-control">


  1. Create a UNIQUE constraint on your subs_email column, if one does not already exist:

    ALTER TABLE subs ADD UNIQUE (subs_email)

    INSERT INTO subs
      (subs_name, subs_email, subs_birthday)
      (?, ?, ?)
      subs_name     = VALUES(subs_name),
      subs_birthday = VALUES(subs_birthday)

You can use the VALUES(col_name) function in the UPDATE clause to refer to column values from the INSERT portion of the INSERT ... ON DUPLICATE KEY UPDATE -

  1. Note that I have used parameter placeholders in the place of string literals, as one really should be using parameterised statements to defend against SQL injection attacks.

how to pass command line arguments to main method dynamically

go to Run Configuration and in argument tab you can write your argument

How to call an element in a numpy array?


Using slicing:

>>> import numpy as np
>>> arr = np.array([[1,2,3,4,5],[6,7,8,9,10]])
>>> arr[0,0]
>>> arr[1,1]
>>> arr[1,0]
>>> arr[1,-1]
>>> arr[1,-2]

In Long:

Hopefully this helps in your understanding:

>>> import numpy as np
>>> np.array([ [1,2,3], [4,5,6] ])
array([[1, 2, 3],
       [4, 5, 6]])
>>> x = np.array([ [1,2,3], [4,5,6] ])
>>> x[1][2] # 2nd row, 3rd column 
>>> x[1,2] # Similarly

But to appreciate why slicing is useful, in more dimensions:

>>> np.array([ [[1,2,3], [4,5,6]], [[7,8,9],[10,11,12]] ])
array([[[ 1,  2,  3],
        [ 4,  5,  6]],

       [[ 7,  8,  9],
        [10, 11, 12]]])
>>> x = np.array([ [[1,2,3], [4,5,6]], [[7,8,9],[10,11,12]] ])

>>> x[1][0][2] # 2nd matrix, 1st row, 3rd column
>>> x[1,0,2] # Similarly

>>> x[1][0:2][2] # 2nd matrix, 1st row, 3rd column
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: index 2 is out of bounds for axis 0 with size 2

>>> x[1, 0:2, 2] # 2nd matrix, 1st and 2nd row, 3rd column
array([ 9, 12])

>>> x[1, 0:2, 1:3] # 2nd matrix, 1st and 2nd row, 2nd and 3rd column
array([[ 8,  9],
       [11, 12]])

How to set JVM parameters for Junit Unit Tests?

I agree with the others who said that there is no simple way to distribute these settings.

For Eclipse: ask your colleagues to set the following:

  • Windows Preferences / Java / Installed JREs:
  • Select the proper JRE/JDK (or do it for all of them)
  • Edit
  • Default VM arguments: -Xmx1024m
  • Finish, OK.

After that all test will run with -Xmx1024m but unfortunately you have set it in every Eclipse installation. Maybe you could create a custom Eclipse package which contains this setting and give it to you co-workers.

The following working process also could help: If the IDE cannot run a test the developer should check that Maven could run this test or not.

  • If Maven could run it the cause of the failure usually is the settings of the developer's IDE. The developer should check these settings.
  • If Maven also could not run the test the developer knows that the cause of the failure is not the IDE, so he/she could use the IDE to debug the test.

How to make circular background using css?

It can be done using the border-radius property. basically, you need to set the border-radius to exactly half of the height and width to get a circle.



<div id="container">
    <div id="inner">


    border:1px black solid;

    -moz-border-radius: 100px;
    -webkit-border-radius: 100px;
    border-radius: 100px;

ImportError: No module named 'google'

According to you need to install google-api-python-client package:

pip install --upgrade google-api-python-client

How do I start an activity from within a Fragment?

I done it, below code is working for me....

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.hello_world, container, false);

        Button newPage = (Button)v.findViewById(;
        newPage.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {
                Intent intent = new Intent(getActivity(), HomeActivity.class);
        return v;

and Please make sure that your destination activity should be register in Manifest.xml file,

but in my case all tabs are not shown in HomeActivity, is any solution for that ?

Limit Get-ChildItem recursion depth

I tried to limit Get-ChildItem recursion depth using Resolve-Path

$PATH = "."
$folder = get-item $PATH 
$FolderFullName = $Folder.FullName
$PATHs = Resolve-Path $FolderFullName\*\*\*\
$Folders = $PATHs | get-item | where {$_.PsIsContainer}

But this works fine :

gci "$PATH\*\*\*\*"

execute shell command from android

A modification of the code by @CarloCannas:

public static void sudo(String...strings) {
        Process su = Runtime.getRuntime().exec("su");
        DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());

        for (String s : strings) {

        try {
        } catch (InterruptedException e) {
    }catch(IOException e){

(You are welcome to find a better place for outputStream.close())

Usage example:

private static void suMkdirs(String path) {
    if (!new File(path).isDirectory()) {
        sudo("mkdir -p "+path);

Update: To get the result (the output to stdout), use:

public static String sudoForResult(String...strings) {
    String res = "";
    DataOutputStream outputStream = null;
    InputStream response = null;
        Process su = Runtime.getRuntime().exec("su");
        outputStream = new DataOutputStream(su.getOutputStream());
        response = su.getInputStream();

        for (String s : strings) {

        try {
        } catch (InterruptedException e) {
        res = readFully(response);
    } catch (IOException e){
    } finally {
        Closer.closeSilently(outputStream, response);
    return res;
public static String readFully(InputStream is) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int length = 0;
    while ((length = != -1) {
        baos.write(buffer, 0, length);
    return baos.toString("UTF-8");

The utility to silently close a number of Closeables (So?ket may be no Closeable) is:

public class Closer {
// closeAll()
public static void closeSilently(Object... xs) {
    // Note: on Android API levels prior to 19 Socket does not implement Closeable
    for (Object x : xs) {
        if (x != null) {
            try {
                Log.d("closing: "+x);
                if (x instanceof Closeable) {
                } else if (x instanceof Socket) {
                } else if (x instanceof DatagramSocket) {
                } else {
                    Log.d("cannot close: "+x);
                    throw new RuntimeException("cannot close "+x);
            } catch (Throwable e) {

How to overwrite existing files in batch?

A command that would copy in any case

xcopy "path\source" "path\destination" /s/h/e/k/f/c/y

How do you convert a byte array to a hexadecimal string, and vice versa?

I did not get the code you suggested to work, Olipro. hex[i] + hex[i+1] apparently returned an int.

I did, however have some success by taking some hints from Waleeds code and hammering this together. It's ugly as hell but it seems to work and performs at 1/3 of the time compared to the others according to my tests (using patridges testing mechanism). Depending on input size. Switching around the ?:s to separate out 0-9 first would probably yield a slightly faster result since there are more numbers than letters.

public static byte[] StringToByteArray2(string hex)
    byte[] bytes = new byte[hex.Length/2];
    int bl = bytes.Length;
    for (int i = 0; i < bl; ++i)
        bytes[i] = (byte)((hex[2 * i] > 'F' ? hex[2 * i] - 0x57 : hex[2 * i] > '9' ? hex[2 * i] - 0x37 : hex[2 * i] - 0x30) << 4);
        bytes[i] |= (byte)(hex[2 * i + 1] > 'F' ? hex[2 * i + 1] - 0x57 : hex[2 * i + 1] > '9' ? hex[2 * i + 1] - 0x37 : hex[2 * i + 1] - 0x30);
    return bytes;

Best way to initialize (empty) array in PHP

Try this:

    $arr = (array) null;

    // will print
    // array(0) { }

Using CSS :before and :after pseudo-elements with inline CSS?

You can't specify inline styles for pseudo-elements.

This is because pseudo-elements, like pseudo-classes (see my answer to this other question), are defined in CSS using selectors as abstractions of the document tree that can't be expressed in HTML. An inline style attribute, on the other hand, is specified within HTML for a particular element.

Since inline styles can only occur in HTML, they will only apply to the HTML element that they're defined on, and not to any pseudo-elements it generates.

As an aside, the main difference between pseudo-elements and pseudo-classes in this aspect is that properties that are inherited by default will be inherited by :before and :after from the generating element, whereas pseudo-class styles just don't apply at all. In your case, for example, if you place text-align: justify in an inline style attribute for a td element, it will be inherited by td:after. The caveat is that you can't declare td:after with the inline style attribute; you must do it in the stylesheet.

Convert string to int if string is a number

Try this: currentLoad = ConvertToLongInteger(oXLSheet2.Cells(4, 6).Value) with this function:

Function ConvertToLongInteger(ByVal stValue As String) As Long
 On Error GoTo ConversionFailureHandler
 ConvertToLongInteger = CLng(stValue)  'TRY to convert to an Integer value
 Exit Function           'If we reach this point, then we succeeded so exit

 'IF we've reached this point, then we did not succeed in conversion
 'If the error is type-mismatch, clear the error and return numeric 0 from the function
 'Otherwise, disable the error handler, and re-run the code to allow the system to 
 'display the error
 If Err.Number = 13 Then 'error # 13 is Type mismatch
      ConvertToLongInteger = 0
      Exit Function
      On Error GoTo 0
 End If
End Function

I chose Long (Integer) instead of simply Integer because the min/max size of an Integer in VBA is crummy (min: -32768, max:+32767). It's common to have an integer outside of that range in spreadsheet operations.

The above code can be modified to handle conversion from string to-Integers, to-Currency (using CCur() ), to-Decimal (using CDec() ), to-Double (using CDbl() ), etc. Just replace the conversion function itself (CLng). Change the function return type, and rename all occurrences of the function variable to make everything consistent.

How to compile without warnings being treated as errors?

If you are compiling linux kernel. For example, if you want to disable the warning that is "unused-but-set-variable" been treated as error. You can add a statement:

KBUILD_CFLAGS += $(call cc-option,-Wno-error=unused-but-set-variable,)

in your Makefile

Get a list of dates between two dates using a function

Answer is avialbe here How to list all dates between two dates

Create Procedure SelectDates(@fromDate Date, @toDate Date)
    SELECT DATEADD(DAY,number,@fromDate) [Date]
    FROM master..spt_values
    WHERE type = 'P'
    AND DATEADD(DAY,number,@fromDate) < @toDate


HTML/Javascript Button Click Counter

Don't use the word "click" as the function name. It's a reserved keyword in JavaScript. In the bellow code I’ve used "hello" function instead of "click"

    <title>Space Clicker</title>

    <script type="text/javascript">

    var clicks = 0;
    function hello() {
        clicks += 1;
        document.getElementById("clicks").innerHTML = clicks;
    <button type="button" onclick="hello()">Click me</button>
    <p>Clicks: <a id="clicks">0</a></p>


How to disable Home and other system buttons in Android?

I followed the shaobin0604's answer and I finally managed to lock the HOME button, by adding:

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

to AndroidManifest.xml All you have to do is to copy from shaobin's lib to your project and implement it like in shaobin's example. BTW: My AVD's Android version is Android 4.0.3.

Replace non ASCII character from string

This would be the Unicode solution

String s = "A função, Ãugent";
String r = s.replaceAll("\\P{InBasic_Latin}", "");

\p{InBasic_Latin} is the Unicode block that contains all letters in the Unicode range U+0000..U+007F (see

\P{InBasic_Latin} is the negated \p{InBasic_Latin}

Validate SSL certificates with Python

pyOpenSSL is an interface to the OpenSSL library. It should provide everything you need.

Global Git ignore

You should create an exclude file for this. Check out this gist which is pretty self explanatory.

To address your question though, you may need to either de-index the .tmproj file (if you've already added it to the index) with git rm --cached path/to/.tmproj, or git add and commit your .gitignore file.

Team Build Error: The Path ... is already mapped to workspace

We had the same problem but deleting the workspace's from the TFS server did not work. (I should mention that I grabbed my colleagues VM that was already set up with his credentials.)

For me this worked:

I just went into the : ...\Local Settings\Application Data\ made a search for VersionControl.config, opened up the folder that contained this file and deleted all of it's contents.

Previous to that I tried manually editing the file but it continued with the same error message.

I hope this helps.

How to Use Multiple Columns in Partition By And Ensure No Duplicate Row is Returned

Try this, It worked for me

                ROW_NUMBER() OVER(PARTITION BY [Code],[Name],[CategoryCode] ORDER BY ID DESC) rownumber
            FROM MasterTable
          ) a
        WHERE rownumber = 1 

How to import keras from tf.keras in Tensorflow?

To make it simple I will take the two versions of the code in keras and tf.keras. The example here is a simple Neural Network Model with different layers in it.

In Keras (v2.1.5)

from keras.models import Sequential
from keras.layers import Dense

def get_model(n_x, n_h1, n_h2):
    model = Sequential()
    model.add(Dense(n_h1, input_dim=n_x, activation='relu'))
    model.add(Dense(n_h2, activation='relu'))
    model.add(Dense(4, activation='softmax'))
    model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
    return model

In tf.keras (v1.9)

import tensorflow as tf

def get_model(n_x, n_h1, n_h2):
    model = tf.keras.Sequential()
    model.add(tf.keras.layers.Dense(n_h1, input_dim=n_x, activation='relu'))
    model.add(tf.keras.layers.Dense(n_h2, activation='relu'))
    model.add(tf.keras.layers.Dense(4, activation='softmax'))
    model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])

    return model

or it can be imported the following way instead of the above-mentioned way

from tensorflow.keras.layers import Dense

The official documentation of tf.keras

Note: TensorFlow Version is 1.9

Copy or rsync command

For a local copy, the only advantage of rsync is that it will avoid copying if the file already exists in the destination directory. The definition of "already exists" is (a) same file name (b) same size (c) same timestamp. (Maybe same owner/group; I am not sure...)

The "rsync algorithm" is great for incremental updates of a file over a slow network link, but it will not buy you much for a local copy, as it needs to read the existing (partial) file to run it's "diff" computation.

So if you are running this sort of command frequently, and the set of changed files is small relative to the total number of files, you should find that rsync is faster than cp. (Also rsync has a --delete option that you might find useful.)

Can I use return value of INSERT...RETURNING in another INSERT?

DO $$
DECLARE tableId integer;
  INSERT INTO Table1 (name) VALUES ('a_title') RETURNING id INTO tableId;
  INSERT INTO Table2 (val) VALUES (tableId);
END $$;

Tested with psql (10.3, server 9.6.8)

onclick="javascript:history.go(-1)" not working in Chrome

Try this dude,

<button onclick="goBack()">Go Back 2 Pages</button>
  function goBack() {

String formatting in Python 3

I like this approach

my_hash = {}
my_hash["goals"] = 3 #to show number
my_hash["penalties"] = "5" #to show string
print("I scored %(goals)d goals and took %(penalties)s penalties" % my_hash)

Note the appended d and s to the brackets respectively.

output will be:

I scored 3 goals and took 5 penalties

What is the difference between i++ and ++i?

int i = 0;
Console.WriteLine(i++); // Prints 0. Then value of "i" becomes 1.
Console.WriteLine(--i); // Value of "i" becomes 0. Then prints 0.

Does this answer your question ?

Android appcompat v7:23

Ran into a similar issue using React Native

> Could not find

the Support Libraries are Local Maven repository for Support Libraries

enter image description here

Checking Maven Version

Step 1: Start button -> Computer menu item -> Properties on right click menu item -> Advanced System Settings button on left panel -> Advanced tab in System Properties dialog -> Environment Variables button -> System variables table

Step 2: Add MAVEN_HOME variable

enter image description here

Step 3: Update PATH variable enter image description here

Step 4: Make sure you have JAVA_HOME variable correctly enter image description here

step 5: open console and check below command

mvn -v

Timestamp with a millisecond precision: How to save them in MySQL

CREATE TABLE fractest( c1 TIME(3), c2 DATETIME(3), c3 TIMESTAMP(3) );

('17:51:04.777', '2018-09-08 17:51:04.777', '2018-09-08 17:51:04.777');

How do I center text horizontally and vertically in a TextView?

We can achieve this with these multiple ways:-

XML method 01


XML method 02


XML method 03


XML method 04


Java method 01

textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.CENTER_HORIZONTAL);

Java method 02


Java method 03


ASP.NET MVC Bundle not rendering script files on staging server. It works on development server

Things to check when enabling the bundle optimization;

BundleTable.EnableOptimizations = true;


webconfig debug = "false"
  1. the bundles.IgnoreList.Clear();

this will ignore the minified assets of your bundles like *.min.css or *.min.js which can cause an undefine error of your script. To fix is replace the .min asset to original. if you do this you may not need the bundles.IgnoreList.Clear(); e.g.

bundles.Add(new ScriptBundle("~/bundles/datatablesjs")
      .Include("~/Scripts/datatables.min.js") <---- change this to non minified ver.
  1. Make sure the names of the bundles of your css and js are unique.

    bundles.Add(new StyleBundle("~/bundles/datatablescss").Include( ...) );

    bundles.Add(new ScriptBundle("~/bundles/datatablesjs").Include( ...) );

  2. Make sure you use the Render name of your @Script.Render and Style.Render are the same on your bundle config. e.g.



What is a constant reference? (not a reference to a constant)

The statement icr=y; does not make the reference refer to y; it assigns the value of y to the variable that icr refers to, i.

References are inherently const, that is you can't change what they refer to. There are 'const references' which are really 'references to const', that is you can't change the value of the object they refer to. They are declared const int& or int const& rather than int& const though.

Could not load file or assembly 'System.Web.Http 4.0.0 after update from 2012 to 2013

The proper solution to resolve this issue is by following the steps

. Update Visual studio if you have older version to 15.5.4 (Optional)

  1. Remove all binding redirects from web.config

  2. Add this to the csproj file:

  1. Build.

  2. In the bin folder, there should be a (WebAppName).dll.config file.

  3. It should have redirects in it. Copy these to the web.config

  4. Remove the above snipped from the csproj file again

  5. It should work

Detailed Blog

How do you split a list into evenly sized chunks?

def split_seq(seq, num_pieces):
    start = 0
    for i in xrange(num_pieces):
        stop = start + len(seq[i::num_pieces])
        yield seq[start:stop]
        start = stop


seq = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

for seq in split_seq(seq, 3):
    print seq

Get selected text from a drop-down list (select box) using jQuery

If you want the result as a list, then use:


Iterating over ResultSet and adding its value in an ArrayList

If I've understood your problem correctly, there are two possible problems here:

  • resultset is null - I assume that this can't be the case as if it was you'd get an exception in your while loop and nothing would be output.
  • The second problem is that resultset.getString(i++) will get columns 1,2,3 and so on from each subsequent row.

I think that the second point is probably your problem here.

Lets say you only had 1 row returned, as follows:

Col 1, Col 2, Col 3 
A    ,     B,     C

Your code as it stands would only get A - it wouldn't get the rest of the columns.

I suggest you change your code as follows:

ResultSet resultset = ...;
ArrayList<String> arrayList = new ArrayList<String>(); 
while ( {                      
    int i = 1;
    while(i <= numberOfColumns) {
    System.out.println(resultset.getString("Col 1"));
    System.out.println(resultset.getString("Col 2"));
    System.out.println(resultset.getString("Col 3"));                    
    System.out.println(resultset.getString("Col n"));


To get the number of columns:

ResultSetMetaData metadata = resultset.getMetaData();
int numberOfColumns = metadata.getColumnCount();

How to find reason of failed Build without any error or warning

On my side, i got this problem when i added a new project (Library)

How i solved it

Right click the new added Library go to Properties then Application, under Application change the Target Framework to the framework of all projects.

The problem is that you have project using different target frameworks.

Difference between Big-O and Little-O Notation

The big-O notation has a companion called small-o notation. The big-O notation says the one function is asymptotical no more than another. To say that one function is asymptotically less than another, we use small-o notation. The difference between the big-O and small-o notations is analogous to the difference between <= (less than equal) and < (less than).

Change Input to Upper Case

If you purpose it to a html input, you can easily do this without the use of JavaScript! or any other JS libraries. It would be standard and very easy to use a CSS tag text-transform:

<input type="text" style="text-transform: uppercase" >

or you can use a bootstrap class named as "text-uppercase"

<input type="text" class="text-uppercase" >

In this manner, your code is much simpler!

How do you access the element HTML from within an Angular attribute directive?

So actually, my comment that you should do a console.log(el.nativeElement) should have pointed you in the right direction, but I didn't expect the output to be just a string representing the DOM Element.

What you have to do to inspect it in the way it helps you with your problem, is to do a console.log(el) in your example, then you'll have access to the nativeElement object and will see a property called innerHTML.

Which will lead to the answer to your original question:

let myCurrentContent:string = el.nativeElement.innerHTML; // get the content of your element
el.nativeElement.innerHTML = 'my new content'; // set content of your element

Update for better approach:

Since it's the accepted answer and web workers are getting more important day to day (and it's considered best practice anyway) I want to add this suggestion by Mark Rajcok here.

The best way to manipulate DOM Elements programmatically is using the Renderer:

constructor(private _elemRef: ElementRef, private _renderer: Renderer) { 
    this._renderer.setElementProperty(this._elemRef.nativeElement, 'innerHTML', 'my new content');


Since Renderer is deprecated now, use Renderer2 instead with setProperty


This question with its answer explained the console.log behavior.

Which means that console.dir(el.nativeElement) would be the more direct way of accessing the DOM Element as an "inspectable" Object in your console for this situation.

Hope this helped.

'node' is not recognized as an internal or an external command, operable program or batch file while using phonegap/cordova

If you install Node using the windows installer, there is nothing you have to do. It adds path to node and npm.

You can also use Windows setx command for changing system environment variables. No reboot is required. Just logout/login. Or just open a new cmd window, if you want to see the changing there.

setx PATH "%PATH%;C:\Program Files\nodejs"

export html table to csv

(1)This is the native javascript solution for this issue. It works on most of modern browsers.

function export2csv() {_x000D_
  let data = "";_x000D_
  const tableData = [];_x000D_
  const rows = document.querySelectorAll("table tr");_x000D_
  for (const row of rows) {_x000D_
    const rowData = [];_x000D_
    for (const [index, column] of row.querySelectorAll("th, td").entries()) {_x000D_
      // To retain the commas in the "Description" column, we can enclose those fields in quotation marks._x000D_
      if ((index + 1) % 3 === 0) {_x000D_
        rowData.push('"' + column.innerText + '"');_x000D_
      } else {_x000D_
  data += tableData.join("\n");_x000D_
  const a = document.createElement("a");_x000D_
  a.href = URL.createObjectURL(new Blob([data], { type: "text/csv" }));_x000D_
  a.setAttribute("download", "data.csv");_x000D_
table {_x000D_
  border-collapse: collapse;_x000D_
td, th {_x000D_
  border: 1px solid #aaa;_x000D_
  padding: 0.5rem;_x000D_
  text-align: left;_x000D_
td {_x000D_
  font-size: 0.875rem;_x000D_
.btn-group {_x000D_
  padding: 1rem 0;_x000D_
button {_x000D_
  background-color: #fff;_x000D_
  border: 1px solid #000;_x000D_
  margin-top: 0.5rem;_x000D_
  border-radius: 3px;_x000D_
  padding: 0.5rem 1rem;_x000D_
  font-size: 1rem;_x000D_
button:hover {_x000D_
  cursor: pointer;_x000D_
  background-color: #000;_x000D_
  color: #fff;_x000D_
      <td>John Resig</td>_x000D_
      <td>The Write Less, Do More, JavaScript Library.</td>_x000D_
      <td>Jordan Walke</td>_x000D_
      <td>React makes it painless to create interactive UIs.</td>_x000D_
      <td>Yuxi You</td>_x000D_
      <td>The Progressive JavaScript Framework.</td>_x000D_
<div class="btn-group">_x000D_
  <button onclick="export2csv()">csv</button>_x000D_

(2) If you want a pure javascript library, FileSaver.js could help you save the code snippets for triggering file download. Besides, FileSaver.js will not be responsible for constructing content for exporting. You have to construct the content by yourself in the format you want.

How do the likely/unlikely macros in the Linux kernel work and what is their benefit?

These are GCC functions for the programmer to give a hint to the compiler about what the most likely branch condition will be in a given expression. This allows the compiler to build the branch instructions so that the most common case takes the fewest number of instructions to execute.

How the branch instructions are built are dependent upon the processor architecture.

How to identify numpy types in python?

To get the type, use the builtin type function. With the in operator, you can test if the type is a numpy type by checking if it contains the string numpy;

In [1]: import numpy as np

In [2]: a = np.array([1, 2, 3])

In [3]: type(a)
Out[3]: <type 'numpy.ndarray'>

In [4]: 'numpy' in str(type(a))
Out[4]: True

(This example was run in IPython, by the way. Very handy for interactive use and quick tests.)

How do I merge changes to a single file, rather than merging commits?

git checkout <target_branch>
git checkout <source_branch> <file_path>

DateTime.Today.ToString("dd/mm/yyyy") returns invalid DateTime Value

Use MM for months. mm is for minutes.


You probably run this code at the begining an hour like (00:00, 05.00, 18.00) and mm gives minutes (00) to your datetime.

From Custom Date and Time Format Strings

"mm" --> The minute, from 00 through 59.

"MM" --> The month, from 01 through 12.

Here is a DEMO. (Which the month part of first line depends on which time do you run this code ;) )

What is the total amount of public IPv4 addresses?

According to Reserved IP addresses there are 588,514,304 reserved addresses and since there are 4,294,967,296 (2^32) IPv4 addressess in total, there are 3,706,452,992 public addresses.

And too many addresses in this post.

You are trying to add a non-nullable field 'new_field' to userprofile without a default

I was early in my development cycle, so this may not work for everyone (but I don't see why it wouldn't).

I added blank=True, null=True to the columns where I was getting the error. Then I ran the python makemigrations command.

Immediately after running this command (and before running python migrate), I removed the blank=True, null=True from all the columns. Then I ran python makemigrations again. I was given an option to just change the columns myself, which I selected.

Then I ran python migrate and everything worked well!

Where to change default pdf page width and font size in jspdf.debug.js?

For anyone trying to this in react. There is a slight difference.

// Document of 8.5 inch width and 11 inch high
new jsPDF('p', 'in', [612, 792]);


// Document of 8.5 inch width and 11 inch high
new jsPDF({
        orientation: 'p', 
        unit: 'in', 
        format: [612, 792]

When i tried the @Aidiakapi solution the pages were tiny. For a difference size take size in inches * 72 to get the dimensions you need. For example, i wanted 8.5 so 8.5 * 72 = 612. This is for [email protected].

how to clear the screen in python

If you mean the screen where you have that interpreter prompt >>> you can do CTRL+L on Bash shell can help. Windows does not have equivalent. You can do

import os
os.system('cls')  # on windows


os.system('clear')  # on linux / os x

How to connect PHP with Microsoft Access database

If you are just getting started with a new project then I would suggest that you use PDO instead of the old odbc_exec() approach. Here is a simple example:

$bits = 8 * PHP_INT_SIZE;
echo "(Info: This script is running as $bits-bit.)\r\n\r\n";

$connStr = 
        'odbc:Driver={Microsoft Access Driver (*.mdb, *.accdb)};' .

$dbh = new PDO($connStr);

$sql = 
        "SELECT AgentName FROM Agents " .
        "WHERE ID < ? AND AgentName <> ?";
$sth = $dbh->prepare($sql);

// query parameter value(s)
$params = array(


while ($row = $sth->fetch()) {
    echo $row['AgentName'] . "\r\n";

NOTE: The above approach is sufficient if you do not need to support Unicode characters above U+00FF. If you do need to support such characters then neither PDO_ODBC nor the old odbc_ functions will work; you'll need to use the solution described in this answer.

Converting stream of int's to char's in java

The answer for conversion of char to int or long is simple casting.

For example:- if you would like to convert Char '0' into long.

Follow simple cast

Char ch='0';
String convertedChar= Character.toString(ch);  //Convert Char to String.
Long finalLongValue=Long.parseLong(convertedChar);


Under what circumstances can I call findViewById with an Options Menu / Action Bar item?

I am trying to obtain a handle on one of the views in the Action Bar

I will assume that you mean something established via android:actionLayout in your <item> element of your <menu> resource.

I have tried calling findViewById(

To retrieve the View associated with your android:actionLayout, call findItem() on the Menu to retrieve the MenuItem, then call getActionView() on the MenuItem. This can be done any time after you have inflated the menu resource.

How to test if a list contains another list?

a=[[1,2] , [3,4] , [0,5,4]]

It provides true output.

a=[[1,2] , [3,4] , [0,5,4]]

It provides false output.

how can I Update top 100 records in sql server

Without an ORDER BY the whole idea of TOP doesn't make much sense. You need to have a consistent definition of which direction is "up" and which is "down" for the concept of top to be meaningful.

Nonetheless SQL Server allows it but doesn't guarantee a deterministic result.

The UPDATE TOP syntax in the accepted answer does not support an ORDER BY clause but it is possible to get deterministic semantics here by using a CTE or derived table to define the desired sort order as below.


jQuery - Disable Form Fields

$('input, select').attr('disabled', 'disabled');

How do you set the Content-Type header for an HttpClient request?

The content type is a header of the content, not of the request, which is why this is failing. AddWithoutValidation as suggested by Robert Levy may work, but you can also set the content type when creating the request content itself (note that the code snippet adds application/json in two places-for Accept and Content-Type headers):

HttpClient client = new HttpClient();
client.BaseAddress = new Uri("");
      .Add(new MediaTypeWithQualityHeaderValue("application/json"));//ACCEPT header

HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "relativeAddress");
request.Content = new StringContent("{\"name\":\"John Doe\",\"age\":33}",
                                    "application/json");//CONTENT-TYPE header

      .ContinueWith(responseTask =>
          Console.WriteLine("Response: {0}", responseTask.Result);

What is “the inverse side of the association” in a bidirectional JPA OneToMany/ManyToOne association?

Table relationships vs. entity relationships

In a relational database system, there can be only three types of table relationships:

  • one-to-many (via a Foreign Key column)
  • one-to-one (via a shared Primary Key)
  • many-to-many (via a link table with two Foreign Keys referencing two separate parent tables)

So, a one-to-many table relationship looks as follows:

one-to-many table relationship

Note that the relationship is based on the Foreign Key column (e.g., post_id) in the child table.

So, there is a single source of truth when it comes to managing a one-to-many table relationship.

Now, if you take a bidirectional entity relationship that maps on the one-to-many table relationship we saw previously:

Bidirectional One-To-Many entity association

If you take a look at the diagram above, you can see that there are two ways to manage this relationship.

In the Post entity, you have the comments collection:

    mappedBy = "post",
    cascade = CascadeType.ALL,
    orphanRemoval = true
private List<PostComment> comments = new ArrayList<>();

And, in the PostComment, the post association is mapped as follows:

    fetch = FetchType.LAZY
@JoinColumn(name = "post_id")
private Post post;

So, you have two sides that can change the entity association:

  • By adding an entry in the comments child collection, a new post_comment row should be associated with the parent post entity via its post_id column.
  • By setting the post property of the PostComment entity, the post_id column should be updated as well.

Because there are two ways to represent the Foreign Key column, you must define which is the source of truth when it comes to translating the association state change into its equivalent Foreign Key column value modification.

MappedBy (a.k.a the inverse side)

The mappedBy attribute tells that the @ManyToOne side is in charge of managing the Foreign Key column, and the collection is used only to fetch the child entities and to cascade parent entity state changes to children (e.g., removing the parent should also remove the child entities).

It's called the inverse side because it references the child entity property that manages this table relationship.

Synchronize both sides of a bidirectional association

Now, even if you defined the mappedBy attribute and the child-side @ManyToOne association manages the Foreign Key column, you still need to synchronize both sides of the bidirectional association.

The best way to do that is to add these two utility methods:

public void addComment(PostComment comment) {

public void removeComment(PostComment comment) {

The addComment and removeComment methods ensure that both sides are synchronized. So, if we add a child entity, the child entity needs to point to the parent and the parent entity should have the child contained in the child collection.

Matplotlib scatterplot; colour as a function of a third variable

There's no need to manually set the colors. Instead, specify a grayscale colormap...

import numpy as np
import matplotlib.pyplot as plt

# Generate data...
x = np.random.random(10)
y = np.random.random(10)

# Plot...
plt.scatter(x, y, c=y, s=500)

enter image description here

Or, if you'd prefer a wider range of colormaps, you can also specify the cmap kwarg to scatter. To use the reversed version of any of these, just specify the "_r" version of any of them. E.g. gray_r instead of gray. There are several different grayscale colormaps pre-made (e.g. gray, gist_yarg, binary, etc).

import matplotlib.pyplot as plt
import numpy as np

# Generate data...
x = np.random.random(10)
y = np.random.random(10)

plt.scatter(x, y, c=y, s=500, cmap='gray')

Does calling clone() on an array also clone its contents?

1D array of primitives does copy elements when it is cloned. This tempts us to clone 2D array(Array of Arrays).

Remember that 2D array clone doesn't work due to shallow copy implementation of clone().

public static void main(String[] args) {
    int row1[] = {0,1,2,3};
    int row2[] =  row1.clone();
    row2[0] = 10;
    System.out.println(row1[0] == row2[0]); // prints false

    int table1[][]={{0,1,2,3},{11,12,13,14}};
    int table2[][] = table1.clone();
    table2[0][0] = 100;
    System.out.println(table1[0][0] == table2[0][0]); //prints true

How to create nested directories using Mkdir in Golang?

This is one alternative for achieving the same but it avoids race condition caused by having two distinct "check ..and.. create" operations.

package main

import (

func main()  {
    if err := ensureDir("/test-dir"); err != nil {
        fmt.Println("Directory creation failed with error: " + err.Error())
    // Proceed forward

func ensureDir(dirName string) error {

    err := os.MkdirAll(dirName, os.ModeDir)

    if err == nil || os.IsExist(err) {
        return nil
    } else {
        return err

Get class list for element with jQuery

A bit late, but using the extend() function lets you call "hasClass()" on any element, e.g.:
var hasClass = $('#divId').hasClass('someClass');

(function($) {
    hasClass: new function(className) {
        var classAttr = $J(this).attr('class');
        if (classAttr != null && classAttr != undefined) {
            var classList = classAttr.split(/\s+/);
            for(var ix = 0, len = classList.length;ix < len;ix++) {
                if (className === classList[ix]) {
                    return true;
        return false;
}); })(jQuery);

C++ How do I convert a std::chrono::time_point to long and back

std::chrono::time_point<std::chrono::system_clock> now = std::chrono::system_clock::now();

This is a great place for auto:

auto now = std::chrono::system_clock::now();

Since you want to traffic at millisecond precision, it would be good to go ahead and covert to it in the time_point:

auto now_ms = std::chrono::time_point_cast<std::chrono::milliseconds>(now);

now_ms is a time_point, based on system_clock, but with the precision of milliseconds instead of whatever precision your system_clock has.

auto epoch = now_ms.time_since_epoch();

epoch now has type std::chrono::milliseconds. And this next statement becomes essentially a no-op (simply makes a copy and does not make a conversion):

auto value = std::chrono::duration_cast<std::chrono::milliseconds>(epoch);


long duration = value.count();

In both your and my code, duration holds the number of milliseconds since the epoch of system_clock.


std::chrono::duration<long> dur(duration);

Creates a duration represented with a long, and a precision of seconds. This effectively reinterpret_casts the milliseconds held in value to seconds. It is a logic error. The correct code would look like:

std::chrono::milliseconds dur(duration);

This line:

std::chrono::time_point<std::chrono::system_clock> dt(dur);

creates a time_point based on system_clock, with the capability of holding a precision to the system_clock's native precision (typically finer than milliseconds). However the run-time value will correctly reflect that an integral number of milliseconds are held (assuming my correction on the type of dur).

Even with the correction, this test will (nearly always) fail though:

if (dt != now)

Because dt holds an integral number of milliseconds, but now holds an integral number of ticks finer than a millisecond (e.g. microseconds or nanoseconds). Thus only on the rare chance that system_clock::now() returned an integral number of milliseconds would the test pass.

But you can instead:

if (dt != now_ms)

And you will now get your expected result reliably.

Putting it all together:

int main ()
    auto now = std::chrono::system_clock::now();
    auto now_ms = std::chrono::time_point_cast<std::chrono::milliseconds>(now);

    auto value = now_ms.time_since_epoch();
    long duration = value.count();

    std::chrono::milliseconds dur(duration);

    std::chrono::time_point<std::chrono::system_clock> dt(dur);

    if (dt != now_ms)
        std::cout << "Failure." << std::endl;
        std::cout << "Success." << std::endl;

Personally I find all the std::chrono overly verbose and so I would code it as:

int main ()
    using namespace std::chrono;
    auto now = system_clock::now();
    auto now_ms = time_point_cast<milliseconds>(now);

    auto value = now_ms.time_since_epoch();
    long duration = value.count();

    milliseconds dur(duration);

    time_point<system_clock> dt(dur);

    if (dt != now_ms)
        std::cout << "Failure." << std::endl;
        std::cout << "Success." << std::endl;

Which will reliably output:


Finally, I recommend eliminating temporaries to reduce the code converting between time_point and integral type to a minimum. These conversions are dangerous, and so the less code you write manipulating the bare integral type the better:

int main ()
    using namespace std::chrono;
    // Get current time with precision of milliseconds
    auto now = time_point_cast<milliseconds>(system_clock::now());
    // sys_milliseconds is type time_point<system_clock, milliseconds>
    using sys_milliseconds = decltype(now);
    // Convert time_point to signed integral type
    auto integral_duration = now.time_since_epoch().count();
    // Convert signed integral type to time_point
    sys_milliseconds dt{milliseconds{integral_duration}};
    // test
    if (dt != now)
        std::cout << "Failure." << std::endl;
        std::cout << "Success." << std::endl;

The main danger above is not interpreting integral_duration as milliseconds on the way back to a time_point. One possible way to mitigate that risk is to write:

    sys_milliseconds dt{sys_milliseconds::duration{integral_duration}};

This reduces risk down to just making sure you use sys_milliseconds on the way out, and in the two places on the way back in.

And one more example: Let's say you want to convert to and from an integral which represents whatever duration system_clock supports (microseconds, 10th of microseconds or nanoseconds). Then you don't have to worry about specifying milliseconds as above. The code simplifies to:

int main ()
    using namespace std::chrono;
    // Get current time with native precision
    auto now = system_clock::now();
    // Convert time_point to signed integral type
    auto integral_duration = now.time_since_epoch().count();
    // Convert signed integral type to time_point
    system_clock::time_point dt{system_clock::duration{integral_duration}};
    // test
    if (dt != now)
        std::cout << "Failure." << std::endl;
        std::cout << "Success." << std::endl;

This works, but if you run half the conversion (out to integral) on one platform and the other half (in from integral) on another platform, you run the risk that system_clock::duration will have different precisions for the two conversions.