Programs & Examples On #Dbtype

SQL Server stored procedure Nullable parameter

You can/should set your parameter to value to DBNull.Value;

if (variable == "")
{
     cmd.Parameters.Add("@Param", SqlDbType.VarChar, 500).Value = DBNull.Value;
}
else
{
     cmd.Parameters.Add("@Param", SqlDbType.VarChar, 500).Value = variable;
}

Or you can leave your server side set to null and not pass the param at all.

SQL Insert Query Using C#

I assume you have a connection to your database and you can not do the insert parameters using c #.

You are not adding the parameters in your query. It should look like:

String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username,@password, @email)";

SqlCommand command = new SqlCommand(query, db.Connection);
command.Parameters.Add("@id","abc");
command.Parameters.Add("@username","abc");
command.Parameters.Add("@password","abc");
command.Parameters.Add("@email","abc");

command.ExecuteNonQuery();

Updated:

using(SqlConnection connection = new SqlConnection(_connectionString))
{
    String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username,@password, @email)";

    using(SqlCommand command = new SqlCommand(query, connection))
    {
        command.Parameters.AddWithValue("@id", "abc");
        command.Parameters.AddWithValue("@username", "abc");
        command.Parameters.AddWithValue("@password", "abc");
        command.Parameters.AddWithValue("@email", "abc");

        connection.Open();
        int result = command.ExecuteNonQuery();

        // Check Error
        if(result < 0)
            Console.WriteLine("Error inserting data into Database!");
    }
}

C# Inserting Data from a form into an access Database

 private void Add_Click(object sender, EventArgs e) {
 OleDbConnection con = new OleDbConnection(@ "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\HP\Desktop\DS Project.mdb");
 OleDbCommand cmd = con.CreateCommand();
 con.Open();
 cmd.CommandText = "Insert into DSPro (Playlist) values('" + textBox1.Text + "')";
 cmd.ExecuteNonQuery();
 MessageBox.Show("Record Submitted", "Congrats");
 con.Close();
} 

Populate data table from data reader

Please check the below code. Automatically it will convert as DataTable

private void ConvertDataReaderToTableManually()
    {
        SqlConnection conn = null;
        try
        {
            string connString = ConfigurationManager.ConnectionStrings["NorthwindConn"].ConnectionString;
            conn = new SqlConnection(connString);
            string query = "SELECT * FROM Customers";
            SqlCommand cmd = new SqlCommand(query, conn);
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            DataTable dtSchema = dr.GetSchemaTable();
            DataTable dt = new DataTable();
            // You can also use an ArrayList instead of List<>
            List<DataColumn> listCols = new List<DataColumn>();

            if (dtSchema != null)
            {
                foreach (DataRow drow in dtSchema.Rows)
                {
                    string columnName = System.Convert.ToString(drow["ColumnName"]);
                    DataColumn column = new DataColumn(columnName, (Type)(drow["DataType"]));
                    column.Unique = (bool)drow["IsUnique"];
                    column.AllowDBNull = (bool)drow["AllowDBNull"];
                    column.AutoIncrement = (bool)drow["IsAutoIncrement"];
                    listCols.Add(column);
                    dt.Columns.Add(column);
                }
            }

            // Read rows from DataReader and populate the DataTable
            while (dr.Read())
            {
                DataRow dataRow = dt.NewRow();
                for (int i = 0; i < listCols.Count; i++)
                {
                    dataRow[((DataColumn)listCols[i])] = dr[i];
                }
                dt.Rows.Add(dataRow);
            }
            GridView2.DataSource = dt;
            GridView2.DataBind();
        }
        catch (SqlException ex)
        {
            // handle error
        }
        catch (Exception ex)
        {
            // handle error
        }
        finally
        {
            conn.Close();
        }

    }

Increasing the Command Timeout for SQL command

Setting CommandTimeout to 120 is not recommended. Try using pagination as mentioned above. Setting CommandTimeout to 30 is considered as normal. Anything more than that is consider bad approach and that usually concludes something wrong with the Implementation. Now the world is running on MiliSeconds Approach.

INSERT VALUES WHERE NOT EXISTS

Ingnoring the duplicated unique constraint isn't a solution?

INSERT IGNORE INTO tblSoftwareTitles...

C# with MySQL INSERT parameters

Use the AddWithValue method:

comm.Parameters.AddWithValue("@person", "Myname");
comm.Parameters.AddWithValue("@address", "Myaddress");

How to Solve Max Connection Pool Error

Before you begin to curse your application you need to check this:

  1. Is your application the only one using that instance of SQL Server. a. If the answer to that is NO then you need to investigate how the other applications are consuming resources on your SQl Server.run b. If the answer is yes then you must investigate your application.

  2. Run SQL Server Profiler and check what activity is happening in other applications (1a) using SQL Server and check your application as well (1b).

  3. If indeed your application is starved off of resources then you need to make farther investigations. For more read on this http://sqlserverplanet.com/troubleshooting/sql-server-slowness

How to show form input fields based on select value?

<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<script>
function myfun(){
$(document).ready(function(){

    $("#select").click(
    function(){
    var data=$("#select").val();
        $("#disp").val(data);
                     });
});
}
</script>
</head>
<body>

<p>id <input type="text" name="user" id="disp"></p>

<select id="select" onclick="myfun()">
<option name="1"value="1">first</option>
<option name="2"value="2">second</option>
</select>

</body>
</html>

Get Return Value from Stored procedure in asp.net

Procedure never returns a value.You have to use a output parameter in store procedure.

ALTER PROC TESTLOGIN
@UserName   varchar(50),
@password   varchar(50)
@retvalue int output
 as
 Begin
    declare @return     int 
    set @return  = (Select COUNT(*) 
    FROM    CPUser  
    WHERE   UserName = @UserName AND Password = @password)

   set @retvalue=@return
  End

Then you have to add a sqlparameter from c# whose parameter direction is out. Hope this make sense.

Using stored procedure output parameters in C#

I slightly modified your stored procedure (to use SCOPE_IDENTITY) and it looks like this:

CREATE PROCEDURE usp_InsertContract
    @ContractNumber varchar(7),
    @NewId int OUTPUT
AS
BEGIN
    INSERT INTO [dbo].[Contracts] (ContractNumber)
    VALUES (@ContractNumber)

    SELECT @NewId = SCOPE_IDENTITY()
END

I tried this and it works just fine (with that modified stored procedure):

// define connection and command, in using blocks to ensure disposal
using(SqlConnection conn = new SqlConnection(pvConnectionString ))
using(SqlCommand cmd = new SqlCommand("dbo.usp_InsertContract", conn))
{
    cmd.CommandType = CommandType.StoredProcedure;

    // set up the parameters
    cmd.Parameters.Add("@ContractNumber", SqlDbType.VarChar, 7);
    cmd.Parameters.Add("@NewId", SqlDbType.Int).Direction = ParameterDirection.Output;

    // set parameter values
    cmd.Parameters["@ContractNumber"].Value = contractNumber;

    // open connection and execute stored procedure
    conn.Open();
    cmd.ExecuteNonQuery();

    // read output value from @NewId
    int contractID = Convert.ToInt32(cmd.Parameters["@NewId"].Value);
    conn.Close();
}

Does this work in your environment, too? I can't say why your original code won't work - but when I do this here, VS2010 and SQL Server 2008 R2, it just works flawlessly....

If you don't get back a value - then I suspect your table Contracts might not really have a column with the IDENTITY property on it.

ExecuteNonQuery: Connection property has not been initialized.

double click on your form to create form_load event.Then inside that event write command.connection = "your connection name";

Difference between Parameters.Add(string, object) and Parameters.AddWithValue

Without explicitly providing the type as in command.Parameters.Add("@ID", SqlDbType.Int);, it will try to implicitly convert the input to what it is expecting.

The downside of this, is that the implicit conversion may not be the most optimal of conversions and may cause a performance hit.

There is a discussion about this very topic here: http://forums.asp.net/t/1200255.aspx/1

How to use OUTPUT parameter in Stored Procedure

You need to close the connection before you can use the output parameters. Something like this

con.Close();
MessageBox.Show(cmd.Parameters["@code"].Value.ToString());

Call a stored procedure with parameter in c#

The .NET Data Providers consist of a number of classes used to connect to a data source, execute commands, and return recordsets. The Command Object in ADO.NET provides a number of Execute methods that can be used to perform the SQL queries in a variety of fashions.

A stored procedure is a pre-compiled executable object that contains one or more SQL statements. In many cases stored procedures accept input parameters and return multiple values . Parameter values can be supplied if a stored procedure is written to accept them. A sample stored procedure with accepting input parameter is given below :

  CREATE PROCEDURE SPCOUNTRY
  @COUNTRY VARCHAR(20)
  AS
  SELECT PUB_NAME FROM publishers WHERE COUNTRY = @COUNTRY
  GO

The above stored procedure is accepting a country name (@COUNTRY VARCHAR(20)) as parameter and return all the publishers from the input country. Once the CommandType is set to StoredProcedure, you can use the Parameters collection to define parameters.

  command.CommandType = CommandType.StoredProcedure;
  param = new SqlParameter("@COUNTRY", "Germany");
  param.Direction = ParameterDirection.Input;
  param.DbType = DbType.String;
  command.Parameters.Add(param);

The above code passing country parameter to the stored procedure from C# application.

using System;
using System.Data;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string connetionString = null;
            SqlConnection connection ;
            SqlDataAdapter adapter ;
            SqlCommand command = new SqlCommand();
            SqlParameter param ;
            DataSet ds = new DataSet();

            int i = 0;

            connetionString = "Data Source=servername;Initial Catalog=PUBS;User ID=sa;Password=yourpassword";
            connection = new SqlConnection(connetionString);

            connection.Open();
            command.Connection = connection;
            command.CommandType = CommandType.StoredProcedure;
            command.CommandText = "SPCOUNTRY";

            param = new SqlParameter("@COUNTRY", "Germany");
            param.Direction = ParameterDirection.Input;
            param.DbType = DbType.String;
            command.Parameters.Add(param);

            adapter = new SqlDataAdapter(command);
            adapter.Fill(ds);

            for (i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
            {
                MessageBox.Show (ds.Tables[0].Rows[i][0].ToString ());
            }

            connection.Close();
        }
    }
}

ORA-01008: not all variables bound. They are bound

I know this is an old question, but it hasn't been correctly addressed, so I'm answering it for others who may run into this problem.

By default Oracle's ODP.net binds variables by position, and treats each position as a new variable.

Treating each copy as a different variable and setting it's value multiple times is a workaround and a pain, as furman87 mentioned, and could lead to bugs, if you are trying to rewrite the query and move things around.

The correct way is to set the BindByName property of OracleCommand to true as below:

var cmd = new OracleCommand(cmdtxt, conn);
cmd.BindByName = true;

You could also create a new class to encapsulate OracleCommand setting the BindByName to true on instantiation, so you don't have to set the value each time. This is discussed in this post

Reading int values from SqlDataReader

Call ToString() instead of casting the reader result.

reader[0].ToString();
reader[1].ToString();
// etc...

And if you want to fetch specific data type values (int in your case) try the following:

reader.GetInt32(index);

C# SQL Server - Passing a list to a stored procedure

CREATE TYPE [dbo].[StringList1] AS TABLE(
[Item] [NVARCHAR](MAX) NULL,
[counts][nvarchar](20) NULL);

create a TYPE as table and name it as"StringList1"

create PROCEDURE [dbo].[sp_UseStringList1]
@list StringList1 READONLY
AS
BEGIN
    -- Just return the items we passed in
    SELECT l.item,l.counts FROM @list l;
    SELECT l.item,l.counts into tempTable FROM @list l;
 End

The create a procedure as above and name it as "UserStringList1" s

String strConnection = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString.ToString();
            SqlConnection con = new SqlConnection(strConnection);
            con.Open();
            var table = new DataTable();

            table.Columns.Add("Item", typeof(string));
            table.Columns.Add("count", typeof(string));

            for (int i = 0; i < 10; i++)
            {
                table.Rows.Add(i.ToString(), (i+i).ToString());

            }
                SqlCommand cmd = new SqlCommand("exec sp_UseStringList1 @list", con);


                    var pList = new SqlParameter("@list", SqlDbType.Structured);
                    pList.TypeName = "dbo.StringList1";
                    pList.Value = table;

                    cmd.Parameters.Add(pList);
                    string result = string.Empty;
                    string counts = string.Empty;
                    var dr = cmd.ExecuteReader();

                    while (dr.Read())
                    {
                        result += dr["Item"].ToString();
                        counts += dr["counts"].ToString();
                    }

in the c#,Try this

How to pass datetime from c# to sql correctly?

You've already done it correctly by using a DateTime parameter with the value from the DateTime, so it should already work. Forget about ToString() - since that isn't used here.

If there is a difference, it is most likely to do with different precision between the two environments; maybe choose a rounding (seconds, maybe?) and use that. Also keep in mind UTC/local/unknown (the DB has no concept of the "kind" of date; .NET does).

I have a table and the date-times in it are in the format: 2011-07-01 15:17:33.357

Note that datetimes in the database aren't in any such format; that is just your query-client showing you white lies. It is stored as a number (and even that is an implementation detail), because humans have this odd tendency not to realise that the date you've shown is the same as 40723.6371916281. Stupid humans. By treating it simply as a "datetime" throughout, you shouldn't get any problems.

Calling stored procedure with return value

Or if you're using EnterpriseLibrary rather than standard ADO.NET...

Database db = DatabaseFactory.CreateDatabase();
using (DbCommand cmd = db.GetStoredProcCommand("usp_GetNewSeqVal"))
{
    db.AddInParameter(cmd, "SeqName", DbType.String, "SeqNameValue");
    db.AddParameter(cmd, "RetVal", DbType.Int32, ParameterDirection.ReturnValue, null, DataRowVersion.Default, null);

    db.ExecuteNonQuery(cmd);

    var result = (int)cmd.Parameters["RetVal"].Value;
}

Object cannot be cast from DBNull to other types

Reason for the error: In an object-oriented programming language, null means the absence of a reference to an object. DBNull represents an uninitialized variant or nonexistent database column. Source:MSDN

Actual Code which I faced error:

Before changed the code:

    if( ds.Tables[0].Rows[0][0] == null ) //   Which is not working

     {
            seqno  = 1; 
      }
    else
    {
          seqno = Convert.ToInt16(ds.Tables[0].Rows[0][0]) + 1;
     }

After changed the code:

   if( ds.Tables[0].Rows[0][0] == DBNull.Value ) //which is working properly
        {
                    seqno  = 1; 
         }
            else
            {
                  seqno = Convert.ToInt16(ds.Tables[0].Rows[0][0]) + 1;
             }

Conclusion: when the database value return the null value, we recommend to use the DBNull class instead of just specifying as a null like in C# language.

How to pass table value parameters to stored procedure from .net code

Use this code to create suitable parameter from your type:

private SqlParameter GenerateTypedParameter(string name, object typedParameter)
{
    DataTable dt = new DataTable();

    var properties = typedParameter.GetType().GetProperties().ToList();
    properties.ForEach(p =>
    {
        dt.Columns.Add(p.Name, Nullable.GetUnderlyingType(p.PropertyType) ?? p.PropertyType);
    });
    var row = dt.NewRow();
    properties.ForEach(p => { row[p.Name] = (p.GetValue(typedParameter) ?? DBNull.Value); });
    dt.Rows.Add(row);

    return new SqlParameter
    {
        Direction = ParameterDirection.Input,
        ParameterName = name,
        Value = dt,
        SqlDbType = SqlDbType.Structured
    };
}

Assign null to a SqlParameter

You need pass DBNull.Value as a null parameter within SQLCommand, unless a default value is specified within stored procedure (if you are using stored procedure). The best approach is to assign DBNull.Value for any missing parameter before query execution, and following foreach will do the job.

foreach (SqlParameter parameter in sqlCmd.Parameters)
{
    if (parameter.Value == null)
    {
        parameter.Value = DBNull.Value;
    }
}

Otherwise change this line:

planIndexParameter.Value = (AgeItem.AgeIndex== null) ? DBNull.Value : AgeItem.AgeIndex;

As follows:

if (AgeItem.AgeIndex== null)
    planIndexParameter.Value = DBNull.Value;
else
    planIndexParameter.Value = AgeItem.AgeIndex;

Because you can't use different type of values in conditional statement, as DBNull and int are different from each other. Hope this will help.

Pass Array Parameter in SqlCommand

I wanted to expand on the answer that Brian contributed to make this easily usable in other places.

/// <summary>
/// This will add an array of parameters to a SqlCommand. This is used for an IN statement.
/// Use the returned value for the IN part of your SQL call. (i.e. SELECT * FROM table WHERE field IN (returnValue))
/// </summary>
/// <param name="sqlCommand">The SqlCommand object to add parameters to.</param>
/// <param name="array">The array of strings that need to be added as parameters.</param>
/// <param name="paramName">What the parameter should be named.</param>
protected string AddArrayParameters(SqlCommand sqlCommand, string[] array, string paramName)
{
    /* An array cannot be simply added as a parameter to a SqlCommand so we need to loop through things and add it manually. 
     * Each item in the array will end up being it's own SqlParameter so the return value for this must be used as part of the
     * IN statement in the CommandText.
     */
    var parameters = new string[array.Length];
    for (int i = 0; i < array.Length; i++)
    {
        parameters[i] = string.Format("@{0}{1}", paramName, i);
        sqlCommand.Parameters.AddWithValue(parameters[i], array[i]);
    }

    return string.Join(", ", parameters);
}

You can use this new function as follows:

SqlCommand cmd = new SqlCommand();

string ageParameters = AddArrayParameters(cmd, agesArray, "Age");
sql = string.Format("SELECT * FROM TableA WHERE Age IN ({0})", ageParameters);

cmd.CommandText = sql;


Edit: Here is a generic variation that works with an array of values of any type and is usable as an extension method:

public static class Extensions
{
    public static void AddArrayParameters<T>(this SqlCommand cmd, string name, IEnumerable<T> values) 
    { 
        name = name.StartsWith("@") ? name : "@" + name;
        var names = string.Join(", ", values.Select((value, i) => { 
            var paramName = name + i; 
            cmd.Parameters.AddWithValue(paramName, value); 
            return paramName; 
        })); 
        cmd.CommandText = cmd.CommandText.Replace(name, names); 
    }
}

You can then use this extension method as follows:

var ageList = new List<int> { 1, 3, 5, 7, 9, 11 };
var cmd = new SqlCommand();
cmd.CommandText = "SELECT * FROM MyTable WHERE Age IN (@Age)";    
cmd.AddArrayParameters("Age", ageList);

Make sure you set the CommandText before calling AddArrayParameters.

Also make sure your parameter name won't partially match anything else in your statement (i.e. @AgeOfChild)

How to pass a null variable to a SQL Stored Procedure from C#.net code

    SQLParam = cmd.Parameters.Add("@RetailerID", SqlDbType.Int, 4)
    If p_RetailerID.Length = 0 Or p_RetailerID = "0" Then
        SQLParam.Value = DBNull.Value
    Else
        SQLParam.Value = p_RetailerID
    End If

What size do you use for varchar(MAX) in your parameter declaration?

The maximum SqlDbType.VarChar size is 2147483647.

If you would use a generic oledb connection instead of sql, I found here there is also a LongVarChar datatype. Its max size is 2147483647.

cmd.Parameters.Add("@blah", OleDbType.LongVarChar, -1).Value = "very big string";

Getting return value from stored procedure in C#

There are multiple problems here:

  1. It is not possible. You are trying to return a varchar. Stored procedure return values can only be integer expressions. See official RETURN documentation: https://msdn.microsoft.com/en-us/library/ms174998.aspx.
  2. Your sqlcomm was never executed. You have to call sqlcomm.ExecuteNonQuery(); in order to execute your command.

Here is a solution using OUTPUT parameters. This was tested with:

  • Windows Server 2012
  • .NET v4.0.30319
  • C# 4.0
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER PROCEDURE [dbo].[Validate]
    @a varchar(50),
    @b varchar(50) OUTPUT
AS
BEGIN
    DECLARE @b AS varchar(50) = (SELECT Password FROM dbo.tblUser WHERE Login = @a)
    SELECT @b;
END
SqlConnection SqlConn = ...
var sqlcomm = new SqlCommand("Validate", SqlConn);

string returnValue = string.Empty;

try
{
    SqlConn.Open();
    sqlcomm.CommandType = CommandType.StoredProcedure;

    SqlParameter param = new SqlParameter("@a", SqlDbType.VarChar);
    param.Direction = ParameterDirection.Input;
    param.Value = Username;
    sqlcomm.Parameters.Add(param);

    SqlParameter output = sqlcomm.Parameters.Add("@b", SqlDbType.VarChar);
    ouput.Direction = ParameterDirection.Output;

    sqlcomm.ExecuteNonQuery(); // This line was missing

    returnValue = output.Value.ToString();

    // ... the rest of code

} catch (SqlException ex) {
    throw ex;
}

How to pass a variable to the SelectCommand of a SqlDataSource?

Try this instead, remove the SelectCommand property and SelectParameters:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:itematConnectionString %>">

Then in the code behind do this:

SqlDataSource1.SelectParameters.Add("userId", userId.ToString());

SqlDataSource1.SelectCommand = "SELECT items.name, items.id FROM items INNER JOIN users_items ON items.id = users_items.id WHERE (users_items.user_id = @userId) ORDER BY users_items.date DESC"

While this worked for me, the following code also works:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:itematConnectionString %>"
    SelectCommand = "SELECT items.name, items.id FROM items INNER JOIN users_items ON items.id = users_items.id WHERE (users_items.user_id = @userId) ORDER BY users_items.date DESC"></asp:SqlDataSource>


SqlDataSource1.SelectParameters.Add("userid", DbType.Guid, userId.ToString());

Using DateTime in a SqlParameter for Stored Procedure, format error

Here is how I add parameters:

sprocCommand.Parameters.Add(New SqlParameter("@Date_Of_Birth",Data.SqlDbType.DateTime))
sprocCommand.Parameters("@Date_Of_Birth").Value = DOB

I am assuming when you write out DOB there are no quotes.

Are you using a third-party control to get the date? I have had problems with the way the text value is generated from some of them.

Lastly, does it work if you type in the .Value attribute of the parameter without referencing DOB?

Procedure expects parameter which was not supplied

This issue is indeed usually caused by setting a parameter value to null as HLGEM mentioned above. I thought i would elaborate on some solutions to this problem that i have found useful for the benefit of people new to this problem.

The solution that i prefer is to default the stored procedure parameters to NULL (or whatever value you want), which was mentioned by sangram above, but may be missed because the answer is very verbose. Something along the lines of:

CREATE PROCEDURE GetEmployeeDetails
    @DateOfBirth    DATETIME = NULL,
    @Surname        VARCHAR(20),
    @GenderCode     INT = NULL,
AS

This means that if the parameter ends up being set in code to null under some conditions, .NET will not set the parameter and the stored procedure will then use the default value it has defined. Another solution, if you really want to solve the problem in code, would be to use an extension method that handles the problem for you, something like:

public static SqlParameter AddParameter<T>(this SqlParameterCollection parameters, string parameterName, T value) where T : class
{
    return value == null ? parameters.AddWithValue(parameterName, DBNull.Value) : parameters.AddWithValue(parameterName, value);
}

Matt Hamilton has a good post here that lists some more great extension methods when dealing with this area.

How do I update/upsert a document in Mongoose?

I needed to update/upsert a document into one collection, what I did was to create a new object literal like this:

notificationObject = {
    user_id: user.user_id,
    feed: {
        feed_id: feed.feed_id,
        channel_id: feed.channel_id,
        feed_title: ''
    }
};

composed from data that I get from somewhere else in my database and then call update on the Model

Notification.update(notificationObject, notificationObject, {upsert: true}, function(err, num, n){
    if(err){
        throw err;
    }
    console.log(num, n);
});

this is the ouput that I get after running the script for the first time:

1 { updatedExisting: false,
    upserted: 5289267a861b659b6a00c638,
    n: 1,
    connectionId: 11,
    err: null,
    ok: 1 }

And this is the output when I run the script for the second time:

1 { updatedExisting: true, n: 1, connectionId: 18, err: null, ok: 1 }

I'm using mongoose version 3.6.16

Remove elements from collection while iterating

why not this?

for( int i = 0; i < Foo.size(); i++ )
{
   if( Foo.get(i).equals( some test ) )
   {
      Foo.remove(i);
   }
}

And if it's a map, not a list, you can use keyset()

how to release localhost from Error: listen EADDRINUSE

I used the command netstat -ano | grep "portnumber" in order to list out the port number/PID for that process. Then, you can use taskkill -f //pid 111111 to kill the process, last value being the pid you find from the first command.

One problem I run into at times is node respawning even after killing the process, so I have to use the good old task manager to manually kill the node process.

How to use wget in php?

To run wget command in PHP you have to do following steps :

1) Allow apache server to use wget command by adding it in sudoers list.

2) Check "exec" function enabled or exist in your PHP config.

3) Run "exec" command as root user i.e. sudo user

Below code sample as per ubuntu machine

#Add apache in sudoers list to use wget command
~$ sudo nano /etc/sudoers
#add below line in the sudoers file
www-data ALL=(ALL) NOPASSWD: /usr/bin/wget


##Now in PHP file run wget command as 
exec("/usr/bin/sudo wget -P PATH_WHERE_WANT_TO_PLACE_FILE URL_OF_FILE");

HTTP Status 500 - Servlet.init() for servlet Dispatcher threw exception

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>teste4</groupId>
    <artifactId>teste4</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <repositories>
        <repository>
            <id>prime-repo</id>
            <name>PrimeFaces Maven Repository</name>
            <url>http://repository.primefaces.org</url>
            <layout>default</layout>
        </repository>
    </repositories>



    <dependencies>
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.2.4</version>
        </dependency>


        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.2.4</version>
        </dependency>



        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces</groupId>
            <artifactId>primefaces</artifactId>
            <version>4.0</version>
        </dependency>
        <dependency>
            <groupId>org.primefaces.themes</groupId>
            <artifactId>bootstrap</artifactId>
            <version>1.0.9</version>
        </dependency>
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.27</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>4.2.7.Final</version>
        </dependency>

    </dependencies>


</project>

How to check if an object implements an interface?

If you want a method like public void doSomething([Object implements Serializable]) you can just type it like this public void doSomething(Serializable serializableObject). You can now pass it any object that implements Serializable but using the serializableObject you only have access to the methods implemented in the object from the Serializable interface.

what is the use of $this->uri->segment(3) in codeigniter pagination

In your code $this->uri->segment(3) refers to the pagination offset which you use in your query. According to your $config['base_url'] = base_url().'index.php/papplicant/viewdeletedrecords/' ;, $this->uri->segment(3) i.e segment 3 refers to the offset. The first segment is the controller, second is the method, there after comes the parameters sent to the controllers as segments.

How to get selected path and name of the file opened with file dialog?

I think this is the simplest way to get to what you want.

Credit to JMK's answer for the first part, and the hyperlink part was adapted from http://msdn.microsoft.com/en-us/library/office/ff822490(v=office.15).aspx

'Gets the entire path to the file including the filename using the open file dialog
Dim filename As String
filename = Application.GetOpenFilename

'Adds a hyperlink to cell b5 in the currently active sheet
With ActiveSheet
 .Hyperlinks.Add Anchor:=.Range("b5"), _
 Address:=filename, _
 ScreenTip:="The screenTIP", _
 TextToDisplay:=filename
End With

Facebook Architecture

Well Facebook has undergone MANY many changes and it wasn't originally designed to be efficient. It was designed to do it's job. I have absolutely no idea what the code looks like and you probably won't find much info about it (for obvious security and copyright reasons), but just take a look at the API. Look at how often it changes and how much of it doesn't work properly, anymore, or at all.

I think the biggest ace up their sleeve is the Hiphop. http://developers.facebook.com/blog/post/358 You can use HipHop yourself: https://github.com/facebook/hiphop-php/wiki

But if you ask me it's a very ambitious and probably time wasting task. Hiphop only supports so much, it can't simply convert everything to C++. So what does this tell us? Well, it tells us that Facebook is NOT fully taking advantage of the PHP language. It's not using the latest 5.3 and I'm willing to bet there's still a lot that is PHP 4 compatible. Otherwise, they couldn't use HipHop. HipHop IS A GOOD IDEA and needs to grow and expand, but in it's current state it's not really useful for that many people who are building NEW PHP apps.

There's also PHP to JAVA via things like Resin/Quercus. Again, it doesn't support everything...

Another thing to note is that if you use any non-standard PHP module, you aren't going to be able to convert that code to C++ or Java either. However...Let's take a look at PHP modules. They are ARE compiled in C++. So if you can build PHP modules that do things (like parse XML, etc.) then you are basically (minus some interaction) working at the same speed. Of course you can't just make a PHP module for every possible need and your entire app because you would have to recompile and it would be much more difficult to code, etc.

However...There are some handy PHP modules that can help with speed concerns. Though at the end of the day, we have this awesome thing known as "the cloud" and with it, we can scale our applications (PHP included) so it doesn't matter as much anymore. Hardware is becoming cheaper and cheaper. Amazon just lowered it's prices (again) speaking of.

So as long as you code your PHP app around the idea that it will need to one day scale...Then I think you're fine and I'm not really sure I'd even look at Facebook and what they did because when they did it, it was a completely different world and now trying to hold up that infrastructure and maintain it...Well, you get things like HipHop.

Now how is HipHop going to help you? It won't. It can't. You're starting fresh, you can use PHP 5.3. I'd highly recommend looking into PHP 5.3 frameworks and all the new benefits that PHP 5.3 brings to the table along with the SPL libraries and also think about your database too. You're most likely serving up content from a database, so check out MongoDB and other types of databases that are schema-less and document-oriented. They are much much faster and better for the most "common" type of web site/app.

Look at NEW companies like Foursquare and Smugmug and some other companies that are utilizing NEW technology and HOW they are using it. For as successful as Facebook is, I honestly would not look at them for "how" to build an efficient web site/app. I'm not saying they don't have very (very) talented people that work there that are solving (their) problems creatively...I'm also not saying that Facebook isn't a great idea in general and that it's not successful and that you shouldn't get ideas from it....I'm just saying that if you could view their entire source code, you probably wouldn't benefit from it.

What is Persistence Context?

"A set of persist-able (entity) instances managed by an entity manager instance at a given time" is called persistence context.

JPA @Entity annotation indicates a persist-able entity.

Refer JPA Definition here

How to identify a strong vs weak relationship on ERD?

  1. Weak (Non-Identifying) Relationship

    • Entity is existence-independent of other enties

    • PK of Child doesn’t contain PK component of Parent Entity

  2. Strong (Identifying) Relationship

    • Child entity is existence-dependent on parent

    • PK of Child Entity contains PK component of Parent Entity

    • Usually occurs utilizing a composite key for primary key, which means one of this composite key components must be the primary key of the parent entity.

POST Content-Length exceeds the limit

post_max_size should be slightly bigger than upload_max_filesize, because when uploading using HTTP POST method the text also includes headers with file size and name, etc.

If you want to successfully uppload 1GiB files, you have to set:

upload_max_filesize = 1024M
post_max_size = 1025M

Note, the correct suffix for GB is G, i.e. upload_max_filesize = 1G.

No need to set memory_limit.

Difference between malloc and calloc?

A difference not yet mentioned: size limit

void *malloc(size_t size) can only allocate up to SIZE_MAX.

void *calloc(size_t nmemb, size_t size); can allocate up about SIZE_MAX*SIZE_MAX.

This ability is not often used in many platforms with linear addressing. Such systems limit calloc() with nmemb * size <= SIZE_MAX.

Consider a type of 512 bytes called disk_sector and code wants to use lots of sectors. Here, code can only use up to SIZE_MAX/sizeof disk_sector sectors.

size_t count = SIZE_MAX/sizeof disk_sector;
disk_sector *p = malloc(count * sizeof *p);

Consider the following which allows an even larger allocation.

size_t count = something_in_the_range(SIZE_MAX/sizeof disk_sector + 1, SIZE_MAX)
disk_sector *p = calloc(count, sizeof *p);

Now if such a system can supply such a large allocation is another matter. Most today will not. Yet it has occurred for many years when SIZE_MAX was 65535. Given Moore's law, suspect this will be occurring about 2030 with certain memory models with SIZE_MAX == 4294967295 and memory pools in the 100 of GBytes.

Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.9.4 or earlier

DT[order(-x)] works as expected. I have data.table version 1.9.4. Maybe this was fixed in a recent version.
Also, I suggest the setorder(DT, -x) syntax in keeping with the set* commands like setnames, setkey

What Does This Mean in PHP -> or =>

The double arrow operator, =>, is used as an access mechanism for arrays. This means that what is on the left side of it will have a corresponding value of what is on the right side of it in array context. This can be used to set values of any acceptable type into a corresponding index of an array. The index can be associative (string based) or numeric.

$myArray = array(
    0 => 'Big',
    1 => 'Small',
    2 => 'Up',
    3 => 'Down'
);

The object operator, ->, is used in object scope to access methods and properties of an object. It’s meaning is to say that what is on the right of the operator is a member of the object instantiated into the variable on the left side of the operator. Instantiated is the key term here.

// Create a new instance of MyObject into $obj
$obj = new MyObject();
// Set a property in the $obj object called thisProperty
$obj->thisProperty = 'Fred';
// Call a method of the $obj object named getProperty
$obj->getProperty();

Is there a CSS selector for the first direct child only?

Use div.section > div.

Better yet, use an <h1> tag for the heading and div.section h1 in your CSS, so as to support older browsers (that don't know about the >) and keep your markup semantic.

Package php5 have no installation candidate (Ubuntu 16.04)

If you just want to install PHP no matter what version it is, try PHP7

sudo apt-get install php7.0 php7.0-mcrypt

Task vs Thread differences

Source

Thread

Thread represents an actual OS-level thread, with its own stack and kernel resources. (technically, a CLR implementation could use fibers instead, but no existing CLR does this) Thread allows the highest degree of control; you can Abort() or Suspend() or Resume() a thread (though this is a very bad idea), you can observe its state, and you can set thread-level properties like the stack size, apartment state, or culture.

The problem with Thread is that OS threads are costly. Each thread you have consumes a non-trivial amount of memory for its stack, and adds additional CPU overhead as the processor context-switch between threads. Instead, it is better to have a small pool of threads execute your code as work becomes available.

There are times when there is no alternative Thread. If you need to specify the name (for debugging purposes) or the apartment state (to show a UI), you must create your own Thread (note that having multiple UI threads is generally a bad idea). Also, if you want to maintain an object that is owned by a single thread and can only be used by that thread, it is much easier to explicitly create a Thread instance for it so you can easily check whether code trying to use it is running on the correct thread.

ThreadPool

ThreadPool is a wrapper around a pool of threads maintained by the CLR. ThreadPool gives you no control at all; you can submit work to execute at some point, and you can control the size of the pool, but you can't set anything else. You can't even tell when the pool will start running the work you submit to it.

Using ThreadPool avoids the overhead of creating too many threads. However, if you submit too many long-running tasks to the threadpool, it can get full, and later work that you submit can end up waiting for the earlier long-running items to finish. In addition, the ThreadPool offers no way to find out when a work item has been completed (unlike Thread.Join()), nor a way to get the result. Therefore, ThreadPool is best used for short operations where the caller does not need the result.

Task

Finally, the Task class from the Task Parallel Library offers the best of both worlds. Like the ThreadPool, a task does not create its own OS thread. Instead, tasks are executed by a TaskScheduler; the default scheduler simply runs on the ThreadPool.

Unlike the ThreadPool, Task also allows you to find out when it finishes, and (via the generic Task) to return a result. You can call ContinueWith() on an existing Task to make it run more code once the task finishes (if it's already finished, it will run the callback immediately). If the task is generic, ContinueWith() will pass you the task's result, allowing you to run more code that uses it.

You can also synchronously wait for a task to finish by calling Wait() (or, for a generic task, by getting the Result property). Like Thread.Join(), this will block the calling thread until the task finishes. Synchronously waiting for a task is usually bad idea; it prevents the calling thread from doing any other work, and can also lead to deadlocks if the task ends up waiting (even asynchronously) for the current thread.

Since tasks still run on the ThreadPool, they should not be used for long-running operations, since they can still fill up the thread pool and block new work. Instead, Task provides a LongRunning option, which will tell the TaskScheduler to spin up a new thread rather than running on the ThreadPool.

All newer high-level concurrency APIs, including the Parallel.For*() methods, PLINQ, C# 5 await, and modern async methods in the BCL, are all built on Task.

Conclusion

The bottom line is that Task is almost always the best option; it provides a much more powerful API and avoids wasting OS threads.

The only reasons to explicitly create your own Threads in modern code are setting per-thread options, or maintaining a persistent thread that needs to maintain its own identity.

How do I change the background color with JavaScript?

You can do it in following ways STEP 1

   var imageUrl= "URL OF THE IMAGE HERE";
   var BackgroundColor="RED"; // what ever color you want

For changing background of BODY

document.body.style.backgroundImage=imageUrl  //changing bg image
document.body.style.backgroundColor=BackgroundColor //changing bg color

To change an element with ID

document.getElementById("ElementId").style.backgroundImage=imageUrl
document.getElementById("ElementId").style.backgroundColor=BackgroundColor 

for elements with same class

   var elements = document.getElementsByClassName("ClassName")
        for (var i = 0; i < elements.length; i++) {
            elements[i].style.background=imageUrl;
        }

Pandas dataframe groupby plot

Similar to Julien's answer above, I had success with the following:

fig, ax = plt.subplots(figsize=(10,4))
for key, grp in df.groupby(['ticker']):
    ax.plot(grp['Date'], grp['adj_close'], label=key)

ax.legend()
plt.show()

This solution might be more relevant if you want more control in matlab.

Solution inspired by: https://stackoverflow.com/a/52526454/10521959

How to detect idle time in JavaScript elegantly?

Debounce actually a great idea! Here version for jQuery free projects:

const derivedLogout = createDerivedLogout(30);
derivedLogout(); // it could happen that user too idle)
window.addEventListener('click', derivedLogout, false);
window.addEventListener('mousemove', derivedLogout, false);
window.addEventListener('keyup', derivedLogout, false); 

function createDerivedLogout (sessionTimeoutInMinutes) {
    return _.debounce( () => {
        window.location = this.logoutUrl;
    }, sessionTimeoutInMinutes * 60 * 1000 ) 
}

UIAlertView first deprecated IOS 9

-(void)showAlert{

    UIAlertController* alert = [UIAlertController alertControllerWithTitle:@"Title"
                                                                   message:"Message"
                                                            preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
                                                          handler:^(UIAlertAction * action) {}];

    [alert addAction:defaultAction];
    [self presentViewController:alert animated:YES completion:nil];
}

[self showAlert]; // calling Method

127 Return code from $?

If you're trying to run a program using a scripting language, you may need to include the full path of the scripting language and the file to execute. For example:

exec('/usr/local/bin/node /usr/local/lib/node_modules/uglifycss/uglifycss in.css > out.css');

PHP add elements to multidimensional array with array_push

As in the multi-dimensional array an entry is another array, specify the index of that value to array_push:

array_push($md_array['recipe_type'], $newdata);

How does jQuery work when there are multiple elements with the same ID value?

you can simply write $('span#a').length to get the length.

Here is the Solution for your code:

console.log($('span#a').length);

try JSfiddle: https://jsfiddle.net/vickyfor2007/wcc0ab5g/2/

How to get HTML 5 input type="date" working in Firefox and/or IE 10

It is in Firefox since version 51 (January 26, 2017), but it is not activated by default (yet)

To activate it:

about:config

dom.forms.datetime -> set to true

https://developer.mozilla.org/en-US/Firefox/Experimental_features

How can I execute a PHP function in a form action?

You can put the username() function in another page, and send the form to that page...

Examples of good gotos in C or C++

Knuth has written a paper "Structured programming with GOTO statements", you can get it e.g. from here. You'll find many examples there.

Postgres: clear entire database before re-creating / re-populating from bash script

If you want to clean your database named "example_db":

1) Login to another db(for example 'postgres'):

psql postgres

2) Remove your database:

DROP DATABASE example_db;

3) Recreate your database:

CREATE DATABASE example_db;

Git merge master into feature branch

Zimi's answer describes this process generally. Here are the specifics:

  1. Create and switch to a new branch. Make sure the new branch is based on master so it will include the recent hotfixes.

    git checkout master
    git branch feature1_new
    git checkout feature1_new
    
    # Or, combined into one command:
    git checkout -b feature1_new master
    
  2. After switching to the new branch, merge the changes from your existing feature branch. This will add your commits without duplicating the hotfix commits.

    git merge feature1
    
  3. On the new branch, resolve any conflicts between your feature and the master branch.

Done! Now use the new branch to continue to develop your feature.

Hibernate Annotations - Which is better, field or property access?

I favor field accessors. The code is much cleaner. All the annotations can be placed in one section of a class and the code is much easier to read.

I found another problem with property accessors: if you have getXYZ methods on your class that are NOT annotated as being associated with persistent properties, hibernate generates sql to attempt to get those properties, resulting in some very confusing error messages. Two hours wasted. I did not write this code; I have always used field accessors in the past and have never run into this issue.

Hibernate versions used in this app:

<!-- hibernate -->
<hibernate-core.version>3.3.2.GA</hibernate-core.version>
<hibernate-annotations.version>3.4.0.GA</hibernate-annotations.version>
<hibernate-commons-annotations.version>3.1.0.GA</hibernate-commons-annotations.version>
<hibernate-entitymanager.version>3.4.0.GA</hibernate-entitymanager.version>

Capture Video of Android's Screen

Yes, use a phone with a video out, and use a video recorder to capture the stream

See this article http://graphics-geek.blogspot.com/2011/02/recording-animations-via-hdmi.html

Avoid "current URL string parser is deprecated" warning by setting useNewUrlParser to true

Updated for ECMAScript 8 / await

The incorrect ECMAScript 8 demo code MongoDB inc provides also creates this warning.

MongoDB provides the following advice, which is incorrect

To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.

Doing this will cause the following error:

TypeError: final argument to executeOperation must be a callback

Instead the option must be provided to new MongoClient:

See the code below:

const DATABASE_NAME = 'mydatabase',
    URL = `mongodb://localhost:27017/${DATABASE_NAME}`

module.exports = async function() {
    const client = new MongoClient(URL, {useNewUrlParser: true})
    var db = null
    try {
        // Note this breaks.
        // await client.connect({useNewUrlParser: true})
        await client.connect()
        db = client.db(DATABASE_NAME)
    } catch (err) {
        console.log(err.stack)
    }

    return db
}

Difference between `npm start` & `node app.js`, when starting app?

From the man page, npm start:

runs a package's "start" script, if one was provided. If no version is specified, then it starts the "active" version.

Admittedly, that description is completely unhelpful, and that's all it says. At least it's more documented than socket.io.

Anyhow, what really happens is that npm looks in your package.json file, and if you have something like

"scripts": { "start": "coffee server.coffee" }

then it will do that. If npm can't find your start script, it defaults to:

node server.js

 

VIM Disable Automatic Newline At End Of File

I've implemented Blixtor's suggestions with Perl and Python post-processing, either running inside Vim (if it is compiled with such language support), or via an external Perl script. It's available as the PreserveNoEOL plugin on vim.org.

SQL use CASE statement in WHERE IN clause

No you can't use case and in like this. But you can do

SELECT * FROM Product P    
WHERE @Status='published' and P.Status IN (1,3)
or @Status='standby' and P.Status IN  (2,5,9,6)
or @Status='deleted' and P.Status IN (4,5,8,10)
or P.Status IN (1,3)

BTW you can reduce that to

SELECT * FROM Product P    
WHERE @Status='standby' and P.Status IN (2,5,9,6)
or @Status='deleted' and P.Status IN (4,5,8,10)
or P.Status IN (1,3)

since or P.Status IN (1,3) gives you also all records of @Status='published' and P.Status IN (1,3)

How to install SimpleJson Package for Python

Really simple way is:

pip install simplejson

Free ASP.Net and/or CSS Themes

I wouldn't bother looking for ASP.NET stuff specifically (probably won't find any anyways). Finding a good CSS theme easily can be used in ASP.NET.

Here's some sites that I love for CSS goodness:

http://www.freecsstemplates.org/
http://www.oswd.org/
http://www.openwebdesign.org/
http://www.styleshout.com/
http://www.freelayouts.com/

In TensorFlow, what is the difference between Session.run() and Tensor.eval()?

If you have a Tensor t, calling t.eval() is equivalent to calling tf.get_default_session().run(t).

You can make a session the default as follows:

t = tf.constant(42.0)
sess = tf.Session()
with sess.as_default():   # or `with sess:` to close on exit
    assert sess is tf.get_default_session()
    assert t.eval() == sess.run(t)

The most important difference is that you can use sess.run() to fetch the values of many tensors in the same step:

t = tf.constant(42.0)
u = tf.constant(37.0)
tu = tf.mul(t, u)
ut = tf.mul(u, t)
with sess.as_default():
   tu.eval()  # runs one step
   ut.eval()  # runs one step
   sess.run([tu, ut])  # evaluates both tensors in a single step

Note that each call to eval and run will execute the whole graph from scratch. To cache the result of a computation, assign it to a tf.Variable.

How to manually trigger validation with jQuery validate?

Eva M from above, almost had the answer as posted above (Thanks Eva M!):

var validator = $( "#myform" ).validate();
validator.form();

This is almost the answer, but it causes problems, in even the most up to date jquery validation plugin as of 13 DEC 2018. The problem is that if one directly copies that sample, and EVER calls ".validate()" more than once, the focus/key processing of the validation can get broken, and the validation may not show errors properly.

Here is how to use Eva M's answer, and ensure those focus/key/error-hiding issues do not occur:

1) Save your validator to a variable/global.

var oValidator = $("#myform").validate();

2) DO NOT call $("#myform").validate() EVER again.

If you call $("#myform").validate() more than once, it may cause focus/key/error-hiding issues.

3) Use the variable/global and call form.

var bIsValid = oValidator.form();

How do I programmatically set the value of a select box element using JavaScript?

Not answering the question, but you can also select by index, where i is the index of the item you wish to select:

var formObj = document.getElementById('myForm');
formObj.leaveCode[i].selected = true;

You can also loop through the items to select by display value with a loop:

for (var i = 0, len < formObj.leaveCode.length; i < len; i++) 
    if (formObj.leaveCode[i].value == 'xxx') formObj.leaveCode[i].selected = true;

Java JDBC connection status

The low-cost method, regardless of the vendor implementation, would be to select something from the process memory or the server memory, like the DB version or the name of the current database. IsClosed is very poorly implemented.

Example:

java.sql.Connection conn = <connect procedure>;
conn.close();
try {
  conn.getMetaData();
} catch (Exception e) {
  System.out.println("Connection is closed");
}

Including .cpp files

Because your program now contains two copies of the foo function, once inside foo.cpp and once inside main.cpp

Think of #include as an instruction to the compiler to copy/paste the contents of that file into your code, so you'll end up with a processed main.cpp that looks like this

#include <iostream> // actually you'll get the contents of the iostream header here, but I'm not going to include it!
int foo(int a){
    return ++a;
}

int main(int argc, char *argv[])
{
int x=42;
std::cout << x <<std::endl;
std::cout << foo(x) << std::endl;
return 0;
}

and foo.cpp

int foo(int a){
    return ++a;
}

hence the multiple definition error

How to run an EXE file in PowerShell with parameters with spaces and quotes

See this page: https://slai.github.io/posts/powershell-and-external-commands-done-right/

Summary using vshadow as the external executable:

$exe = "H:\backup\scripts\vshadow.exe"
&$exe -p -script=H:\backup\scripts\vss.cmd E: M: P:

Prevent scrolling of parent element when inner element scroll position reaches top/bottom?

Simple solution with mouseweel event:

$('.element').bind('mousewheel', function(e, d) {
    console.log(this.scrollTop,this.scrollHeight,this.offsetHeight,d);
    if((this.scrollTop === (this.scrollHeight - this.offsetHeight) && d < 0)
        || (this.scrollTop === 0 && d > 0)) {
        e.preventDefault();
    }
});

When to use MyISAM and InnoDB?

Use MyISAM for very unimportant data or if you really need those minimal performance advantages. The read performance is not better in every case for MyISAM.

I would personally never use MyISAM at all anymore. Choose InnoDB and throw a bit more hardware if you need more performance. Another idea is to look at database systems with more features like PostgreSQL if applicable.

EDIT: For the read-performance, this link shows that innoDB often is actually not slower than MyISAM: https://www.percona.com/blog/2007/01/08/innodb-vs-myisam-vs-falcon-benchmarks-part-1/

How to install node.js as windows service?

I found the thing so useful that I built an even easier to use wrapper around it (npm, github).

Installing it:

npm install -g qckwinsvc

Installing your service:

qckwinsvc

prompt: Service name: [name for your service]
prompt: Service description: [description for it]
prompt: Node script path: [path of your node script]
Service installed

Uninstalling your service:

qckwinsvc --uninstall

prompt: Service name: [name of your service]
prompt: Node script path: [path of your node script]
Service stopped
Service uninstalled

How to use glOrtho() in OpenGL?

Minimal runnable example

glOrtho: 2D games, objects close and far appear the same size:

enter image description here

glFrustrum: more real-life like 3D, identical objects further away appear smaller:

enter image description here

main.c

#include <stdlib.h>

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

static int ortho = 0;

static void display(void) {
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    if (ortho) {
    } else {
        /* This only rotates and translates the world around to look like the camera moved. */
        gluLookAt(0.0, 0.0, -3.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
    }
    glColor3f(1.0f, 1.0f, 1.0f);
    glutWireCube(2);
    glFlush();
}

static void reshape(int w, int h) {
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (ortho) {
        glOrtho(-2.0, 2.0, -2.0, 2.0, -1.5, 1.5);
    } else {
        glFrustum(-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);
    }
    glMatrixMode(GL_MODELVIEW);
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    if (argc > 1) {
        ortho = 1;
    }
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(100, 100);
    glutCreateWindow(argv[0]);
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glShadeModel(GL_FLAT);
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutMainLoop();
    return EXIT_SUCCESS;
}

GitHub upstream.

Compile:

gcc -ggdb3 -O0 -o main -std=c99 -Wall -Wextra -pedantic main.c -lGL -lGLU -lglut

Run with glOrtho:

./main 1

Run with glFrustrum:

./main

Tested on Ubuntu 18.10.

Schema

Ortho: camera is a plane, visible volume a rectangle:

enter image description here

Frustrum: camera is a point,visible volume a slice of a pyramid:

enter image description here

Image source.

Parameters

We are always looking from +z to -z with +y upwards:

glOrtho(left, right, bottom, top, near, far)
  • left: minimum x we see
  • right: maximum x we see
  • bottom: minimum y we see
  • top: maximum y we see
  • -near: minimum z we see. Yes, this is -1 times near. So a negative input means positive z.
  • -far: maximum z we see. Also negative.

Schema:

Image source.

How it works under the hood

In the end, OpenGL always "uses":

glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);

If we use neither glOrtho nor glFrustrum, that is what we get.

glOrtho and glFrustrum are just linear transformations (AKA matrix multiplication) such that:

  • glOrtho: takes a given 3D rectangle into the default cube
  • glFrustrum: takes a given pyramid section into the default cube

This transformation is then applied to all vertexes. This is what I mean in 2D:

Image source.

The final step after transformation is simple:

  • remove any points outside of the cube (culling): just ensure that x, y and z are in [-1, +1]
  • ignore the z component and take only x and y, which now can be put into a 2D screen

With glOrtho, z is ignored, so you might as well always use 0.

One reason you might want to use z != 0 is to make sprites hide the background with the depth buffer.

Deprecation

glOrtho is deprecated as of OpenGL 4.5: the compatibility profile 12.1. "FIXED-FUNCTION VERTEX TRANSFORMATIONS" is in red.

So don't use it for production. In any case, understanding it is a good way to get some OpenGL insight.

Modern OpenGL 4 programs calculate the transformation matrix (which is small) on the CPU, and then give the matrix and all points to be transformed to OpenGL, which can do the thousands of matrix multiplications for different points really fast in parallel.

Manually written vertex shaders then do the multiplication explicitly, usually with the convenient vector data types of the OpenGL Shading Language.

Since you write the shader explicitly, this allows you to tweak the algorithm to your needs. Such flexibility is a major feature of more modern GPUs, which unlike the old ones that did a fixed algorithm with some input parameters, can now do arbitrary computations. See also: https://stackoverflow.com/a/36211337/895245

With an explicit GLfloat transform[] it would look something like this:

glfw_transform.c

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

#define GLEW_STATIC
#include <GL/glew.h>

#include <GLFW/glfw3.h>

static const GLuint WIDTH = 800;
static const GLuint HEIGHT = 600;
/* ourColor is passed on to the fragment shader. */
static const GLchar* vertex_shader_source =
    "#version 330 core\n"
    "layout (location = 0) in vec3 position;\n"
    "layout (location = 1) in vec3 color;\n"
    "out vec3 ourColor;\n"
    "uniform mat4 transform;\n"
    "void main() {\n"
    "    gl_Position = transform * vec4(position, 1.0f);\n"
    "    ourColor = color;\n"
    "}\n";
static const GLchar* fragment_shader_source =
    "#version 330 core\n"
    "in vec3 ourColor;\n"
    "out vec4 color;\n"
    "void main() {\n"
    "    color = vec4(ourColor, 1.0f);\n"
    "}\n";
static GLfloat vertices[] = {
/*   Positions          Colors */
     0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f,
    -0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f,
     0.0f,  0.5f, 0.0f, 0.0f, 0.0f, 1.0f
};

/* Build and compile shader program, return its ID. */
GLuint common_get_shader_program(
    const char *vertex_shader_source,
    const char *fragment_shader_source
) {
    GLchar *log = NULL;
    GLint log_length, success;
    GLuint fragment_shader, program, vertex_shader;

    /* Vertex shader */
    vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
    glCompileShader(vertex_shader);
    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
    glGetShaderiv(vertex_shader, GL_INFO_LOG_LENGTH, &log_length);
    log = malloc(log_length);
    if (log_length > 0) {
        glGetShaderInfoLog(vertex_shader, log_length, NULL, log);
        printf("vertex shader log:\n\n%s\n", log);
    }
    if (!success) {
        printf("vertex shader compile error\n");
        exit(EXIT_FAILURE);
    }

    /* Fragment shader */
    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
    glCompileShader(fragment_shader);
    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
    glGetShaderiv(fragment_shader, GL_INFO_LOG_LENGTH, &log_length);
    if (log_length > 0) {
        log = realloc(log, log_length);
        glGetShaderInfoLog(fragment_shader, log_length, NULL, log);
        printf("fragment shader log:\n\n%s\n", log);
    }
    if (!success) {
        printf("fragment shader compile error\n");
        exit(EXIT_FAILURE);
    }

    /* Link shaders */
    program = glCreateProgram();
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    glLinkProgram(program);
    glGetProgramiv(program, GL_LINK_STATUS, &success);
    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
    if (log_length > 0) {
        log = realloc(log, log_length);
        glGetProgramInfoLog(program, log_length, NULL, log);
        printf("shader link log:\n\n%s\n", log);
    }
    if (!success) {
        printf("shader link error");
        exit(EXIT_FAILURE);
    }

    /* Cleanup. */
    free(log);
    glDeleteShader(vertex_shader);
    glDeleteShader(fragment_shader);
    return program;
}

int main(void) {
    GLint shader_program;
    GLint transform_location;
    GLuint vbo;
    GLuint vao;
    GLFWwindow* window;
    double time;

    glfwInit();
    window = glfwCreateWindow(WIDTH, HEIGHT, __FILE__, NULL, NULL);
    glfwMakeContextCurrent(window);
    glewExperimental = GL_TRUE;
    glewInit();
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glViewport(0, 0, WIDTH, HEIGHT);

    shader_program = common_get_shader_program(vertex_shader_source, fragment_shader_source);

    glGenVertexArrays(1, &vao);
    glGenBuffers(1, &vbo);
    glBindVertexArray(vao);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    /* Position attribute */
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);
    /* Color attribute */
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(1);
    glBindVertexArray(0);

    while (!glfwWindowShouldClose(window)) {
        glfwPollEvents();
        glClear(GL_COLOR_BUFFER_BIT);

        glUseProgram(shader_program);
        transform_location = glGetUniformLocation(shader_program, "transform");
        /* THIS is just a dummy transform. */
        GLfloat transform[] = {
            0.0f, 0.0f, 0.0f, 0.0f,
            0.0f, 0.0f, 0.0f, 0.0f,
            0.0f, 0.0f, 1.0f, 0.0f,
            0.0f, 0.0f, 0.0f, 1.0f,
        };
        time = glfwGetTime();
        transform[0] = 2.0f * sin(time);
        transform[5] = 2.0f * cos(time);
        glUniformMatrix4fv(transform_location, 1, GL_FALSE, transform);

        glBindVertexArray(vao);
        glDrawArrays(GL_TRIANGLES, 0, 3);
        glBindVertexArray(0);
        glfwSwapBuffers(window);
    }
    glDeleteVertexArrays(1, &vao);
    glDeleteBuffers(1, &vbo);
    glfwTerminate();
    return EXIT_SUCCESS;
}

GitHub upstream.

Compile and run:

gcc -ggdb3 -O0 -o glfw_transform.out -std=c99 -Wall -Wextra -pedantic glfw_transform.c -lGL -lGLU -lglut -lGLEW -lglfw -lm
./glfw_transform.out

Output:

enter image description here

The matrix for glOrtho is really simple, composed only of scaling and translation:

scalex, 0,      0,      translatex,
0,      scaley, 0,      translatey,
0,      0,      scalez, translatez,
0,      0,      0,      1

as mentioned in the OpenGL 2 docs.

The glFrustum matrix is not too hard to calculate by hand either, but starts getting annoying. Note how frustum cannot be made up with only scaling and translations like glOrtho, more info at: https://gamedev.stackexchange.com/a/118848/25171

The GLM OpenGL C++ math library is a popular choice for calculating such matrices. http://glm.g-truc.net/0.9.2/api/a00245.html documents both an ortho and frustum operations.

How to get the file path from URI?

File myFile = new File(uri.toString());
myFile.getAbsolutePath()

should return u the correct path

EDIT

As @Tron suggested the working code is

File myFile = new File(uri.getPath());
myFile.getAbsolutePath()

Multiple inputs on one line

Yes, you can input multiple items from cin, using exactly the syntax you describe. The result is essentially identical to:

cin >> a;
cin >> b;
cin >> c;

This is due to a technique called "operator chaining".

Each call to operator>>(istream&, T) (where T is some arbitrary type) returns a reference to its first argument. So cin >> a returns cin, which can be used as (cin>>a)>>b and so forth.

Note that each call to operator>>(istream&, T) first consumes all whitespace characters, then as many characters as is required to satisfy the input operation, up to (but not including) the first next whitespace character, invalid character, or EOF.

How can I check if a Perl array contains a particular value?

Simply turn the array into a hash:

my %params = map { $_ => 1 } @badparams;

if(exists($params{$someparam})) { ... }

You can also add more (unique) params to the list:

$params{$newparam} = 1;

And later get a list of (unique) params back:

@badparams = keys %params;

How to change the default charset of a MySQL table?

The ALTER TABLE MySQL command should do the trick. The following command will change the default character set of your table and the character set of all its columns to UTF8.

ALTER TABLE etape_prospection CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;

This command will convert all text-like columns in the table to the new character set. Character sets use different amounts of data per character, so MySQL will convert the type of some columns to ensure there's enough room to fit the same number of characters as the old column type.

I recommend you read the ALTER TABLE MySQL documentation before modifying any live data.

EC2 instance has no public DNS

In my case I found the answer from slayedbylucifer and others that point to the same are valid.
Even it is set that DNS hostname: yes, no Public IP is assigned on my-pvc (only Privat IP).

It is definitely that Auto assign Public IP has to be set Enable.
If it is not selected, then by default it sets to Use subnet setting (Disable)

Assign Public IP

How do I check if a string is a number (float)?

Which, not only is ugly and slow, seems clunky.

It may take some getting used to, but this is the pythonic way of doing it. As has been already pointed out, the alternatives are worse. But there is one other advantage of doing things this way: polymorphism.

The central idea behind duck typing is that "if it walks and talks like a duck, then it's a duck." What if you decide that you need to subclass string so that you can change how you determine if something can be converted into a float? Or what if you decide to test some other object entirely? You can do these things without having to change the above code.

Other languages solve these problems by using interfaces. I'll save the analysis of which solution is better for another thread. The point, though, is that python is decidedly on the duck typing side of the equation, and you're probably going to have to get used to syntax like this if you plan on doing much programming in Python (but that doesn't mean you have to like it of course).

One other thing you might want to take into consideration: Python is pretty fast in throwing and catching exceptions compared to a lot of other languages (30x faster than .Net for instance). Heck, the language itself even throws exceptions to communicate non-exceptional, normal program conditions (every time you use a for loop). Thus, I wouldn't worry too much about the performance aspects of this code until you notice a significant problem.

Phone mask with jQuery and Masked Input Plugin

As alternative

    function FormatPhone(tt,e){
  //console.log(e.which);
  var t = $(tt);
  var v1 = t.val();
  var k = e.which;
  if(k!=8 && v1.length===18){
    e.preventDefault();
  }
  var q = String.fromCharCode((96 <= k && k <= 105)? k-48 : k);
  if (((e.shiftKey || (e.keyCode < 48 || e.keyCode > 57)) && (e.keyCode < 96 || e.keyCode > 105)) && e.keyCode!=46 && e.keyCode!=37 && e.keyCode!=8 && e.keyCode!=39) {
 e.preventDefault();
  }
  else{
    setTimeout(function(){
      var v = t.val();
      var l = v.length;
      //console.log(l);
      if(k!=8){
        if(l<4){
          t.val('+7 ');
        }
        else if(l===4){
          if(isNaN(q)){
            t.val('+7 (');
          }
          else{
            t.val('+7 ('+q);
          }
        }
        else if(l===7){
          t.val(v+')');
        }
        else if(l===9){
          t.val(v1+' '+q);
        }
        else if(l===13||l===16){
          t.val(v1+'-'+q);
        }
        else if(l>18){
          v=v.substr(0,18);
          t.val(v);
        }
        }
        else{
          if(l<4){
            t.val('+7 ');
          }
        }
    },100);
  }
}

how to send multiple data with $.ajax() jquery

Change var data = 'id='+ id & 'name='+ name; as below,

use this instead.....

var data = "id="+ id + "&name=" + name;

this will going to work fine:)

How do I draw a set of vertical lines in gnuplot?

alternatively you can also do this:

p '< echo "x y"' w impulse

x and y are the coordinates of the point to which you draw a vertical bar

Text not wrapping in p tag

Give this style to the <p> tag.

p {
    word-break: break-all;
    white-space: normal;
}

How do you enable auto-complete functionality in Visual Studio C++ express edition?

  • Goto => Tools >> Options >> Text Editor >> C/C++ >> Advanced >> IntelliSense
  • Change => Member List Commit Aggressive to True

ios simulator: how to close an app

Command + shift +h Press H 2 times

Note :- Press H 2 times

CSS z-index not working (position absolute)

I was struggling to figure it out how to put a div over an image like this: z-index working

No matter how I configured z-index in both divs (the image wrapper) and the section I was getting this:

z-index Not working

Turns out I hadn't set up the background of the section to be background: white;

so basically it's like this:

<div class="img-wrp">
  <img src="myimage.svg"/>
</div>
<section>
 <other content>
</section>

section{
  position: relative;
  background: white; /* THIS IS THE IMPORTANT PART NOT TO FORGET */
}
.img-wrp{
  position: absolute;
  z-index: -1; /* also worked with 0 but just to be sure */
}

JQuery datepicker language

A quick Update, for the text "Today", the right names are:

todayText: 'Huidige', todayStatus: 'Bekijk de huidige maand',

Simple if else onclick then do?

You should use onclick method because the function run once when the page is loaded and no button will be clicked then

So you have to add an even which run every time the user press any key to add the changes to the div background

So the function should be something like this

htmlelement.onclick() = function(){
    //Do the changes 
}

So your code has to look something like this :

var box = document.getElementById("box");
var yes = document.getElementById("yes");
var no = document.getElementById("no");

yes.onclick = function(){
    box.style.backgroundColor = "red";
}

no.onclick = function(){
    box.style.backgroundColor = "green";
}

This is meaning that when #yes button is clicked the color of the div is red and when the #no button is clicked the background is green

Here is a Jsfiddle

make arrayList.toArray() return more specific types

I got the answer...this seems to be working perfectly fine

public int[] test ( int[]b )
{
    ArrayList<Integer> l = new ArrayList<Integer>();
    Object[] returnArrayObject = l.toArray();
    int returnArray[] = new int[returnArrayObject.length];
    for (int i = 0; i < returnArrayObject.length; i++){
         returnArray[i] = (Integer)  returnArrayObject[i];
    }

    return returnArray;
}

How to push to History in React Router v4?

this.context.history.push will not work.

I managed to get push working like this:

static contextTypes = {
    router: PropTypes.object
}

handleSubmit(e) {
    e.preventDefault();

    if (this.props.auth.success) {
        this.context.router.history.push("/some/Path")
    }

}

Image style height and width not taken in outlook mails

The px needs to be left off, for some odd reason.

How can I get the ID of an element using jQuery?

id is a property of an html Element. However, when you write $("#something"), it returns a jQuery object that wraps the matching DOM element(s). To get the first matching DOM element back, call get(0)

$("#test").get(0)

On this native element, you can call id, or any other native DOM property or function.

$("#test").get(0).id

That's the reason why id isn't working in your code.

Alternatively, use jQuery's attr method as other answers suggest to get the id attribute of the first matching element.

$("#test").attr("id")

How to set shape's opacity?

use this code below as progress.xml:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:id="@android:id/background">
        <shape>
            <corners android:radius="5dip" />
            <gradient
                    android:startColor="#ff9d9e9d"
                    android:centerColor="#ff5a5d5a"
                    android:centerY="0.75"
                    android:endColor="#ff747674"
                    android:angle="270"
            />
        </shape>
    </item>

    <item android:id="@android:id/secondaryProgress">
        <clip>
            <shape>
                <solid android:color="#00000000" />
            </shape>
        </clip>
    </item>

    <item android:id="@android:id/progress">
        <clip>
            <shape>
                <solid android:color="#00000000" />
            </shape>
        </clip>
    </item>

</layer-list>

where:

  • "progress" is current progress before the thumb and "secondaryProgress" is the progress after thumb.
  • color="#00000000" is a perfect transparency
  • NOTE: the file above is from default android res and is for 2.3.7, it is available on android sources at: frameworks/base/core/res/res/drawable/progress_horizontal.xml. For newer versions you must find the default drawable file for the seekbar corresponding to your android version.

after that use it in the layout containing the xml:

<SeekBar
    android:id="@+id/myseekbar"
    ...
    android:progressDrawable="@drawable/progress"
    />

you can also customize the thumb by using a custom icon seek_thumb.png:

android:thumb="@drawable/seek_thumb"

#pragma pack effect

Compiler could align members in structures to achieve maximum performance on the certain platform. #pragma pack directive allows you to control that alignment. Usually you should leave it by default for optimum performance. If you need to pass a structure to the remote machine you generally will use #pragma pack 1 to exclude any unwanted alignment.

How to map atan2() to degrees 0-360

A formula to have the range of values from 0 to 360 degrees.

f(x,y)=180-90*(1+sign(x))* (1-sign(y^2))-45*(2+sign(x))*sign(y)

     -(180/pi())*sign(x*y)*atan((abs(x)-abs(y))/(abs(x)+abs(y)))

JavaScript/jQuery: replace part of string?

You need to set the text after the replace call:

_x000D_
_x000D_
$('.element span').each(function() {_x000D_
  console.log($(this).text());_x000D_
  var text = $(this).text().replace('N/A, ', '');_x000D_
  $(this).text(text);_x000D_
});
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>_x000D_
<div class="element">_x000D_
  <span>N/A, Category</span>_x000D_
</div>
_x000D_
_x000D_
_x000D_


Here's another cool way you can do it (hat tip @Felix King):

$(".element span").text(function(index, text) {
    return text.replace("N/A, ", "");
});

Laravel 5: Retrieve JSON array from $request

My jQuery ajax settings:

        $.ajax({
        headers: {'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')},
        url: url,
        dataType: "json",
        type: "post",
        data: params,
        success: function (resp){
            ....
        },
        error: responseFunc
    });

And now i am able to get the request via $request->all() in Laravel

dataType: "json"

is the important part in the ajax request to handle the response as an json object and not string.

checking if a number is divisible by 6 PHP

I see some of the other answers calling the modulo twice.

My preference is not to ask php to do the same thing more than once. For this reason, I cache the remainder.

Other devs may prefer to not generate the extra global variable or have other justifications for using modulo operator twice.

Code: (Demo)

$factor = 6;
for($x = 0; $x < 10; ++$x){  // battery of 10 tests
    $number = rand( 0 , 100 );
    echo "Number: $number Becomes: ";
    if( $remainder = $number % $factor ) {  // if not zero
        $number += $factor - $remainder;  // use cached $remainder instead of calculating again
    }
    echo "$number\n";
}

Possible Output:

Number: 80 Becomes: 84
Number: 57 Becomes: 60
Number: 94 Becomes: 96
Number: 48 Becomes: 48
Number: 80 Becomes: 84
Number: 36 Becomes: 36
Number: 17 Becomes: 18
Number: 41 Becomes: 42
Number: 3 Becomes: 6
Number: 64 Becomes: 66

In Android EditText, how to force writing uppercase?

Rather than worry about dealing with the keyboard, why not just accept any input, lowercase or uppercase and convert the string to uppercase?

The following code should help:

EditText edit = (EditText)findViewById(R.id.myEditText);
String input;
....
input = edit.getText();
input = input.toUpperCase(); //converts the string to uppercase

This is user-friendly since it is unnecessary for the user to know that you need the string in uppercase. Hope this helps.

Get each line from textarea

$array = explode("\n", $text);
for($i=0; $i < count($array); $i++)
{
    echo $line;
    if($i < count($array)-1)
    {
         echo '<br />';
    }
}

Referring to the null object in Python

None, Python's null?

There's no null in Python; instead there's None. As stated already, the most accurate way to test that something has been given None as a value is to use the is identity operator, which tests that two variables refer to the same object.

>>> foo is None
True
>>> foo = 'bar'
>>> foo is None
False

The basics

There is and can only be one None

None is the sole instance of the class NoneType and any further attempts at instantiating that class will return the same object, which makes None a singleton. Newcomers to Python often see error messages that mention NoneType and wonder what it is. It's my personal opinion that these messages could simply just mention None by name because, as we'll see shortly, None leaves little room to ambiguity. So if you see some TypeError message that mentions that NoneType can't do this or can't do that, just know that it's simply the one None that was being used in a way that it can't.

Also, None is a built-in constant. As soon as you start Python, it's available to use from everywhere, whether in module, class, or function. NoneType by contrast is not, you'd need to get a reference to it first by querying None for its class.

>>> NoneType
NameError: name 'NoneType' is not defined
>>> type(None)
NoneType

You can check None's uniqueness with Python's identity function id(). It returns the unique number assigned to an object, each object has one. If the id of two variables is the same, then they point in fact to the same object.

>>> NoneType = type(None)
>>> id(None)
10748000
>>> my_none = NoneType()
>>> id(my_none)
10748000
>>> another_none = NoneType()
>>> id(another_none)
10748000
>>> def function_that_does_nothing(): pass
>>> return_value = function_that_does_nothing()
>>> id(return_value)
10748000

None cannot be overwritten

In much older versions of Python (before 2.4) it was possible to reassign None, but not any more. Not even as a class attribute or in the confines of a function.

# In Python 2.7
>>> class SomeClass(object):
...     def my_fnc(self):
...             self.None = 'foo'
SyntaxError: cannot assign to None
>>> def my_fnc():
        None = 'foo'
SyntaxError: cannot assign to None

# In Python 3.5
>>> class SomeClass:
...     def my_fnc(self):
...             self.None = 'foo'
SyntaxError: invalid syntax
>>> def my_fnc():
        None = 'foo'
SyntaxError: cannot assign to keyword

It's therefore safe to assume that all None references are the same. There isn't any "custom" None.

To test for None use the is operator

When writing code you might be tempted to test for Noneness like this:

if value==None:
    pass

Or to test for falsehood like this

if not value:
    pass

You need to understand the implications and why it's often a good idea to be explicit.

Case 1: testing if a value is None

Why do

value is None

rather than

value==None

?

The first is equivalent to:

id(value)==id(None)

Whereas the expression value==None is in fact applied like this

value.__eq__(None)

If the value really is None then you'll get what you expected.

>>> nothing = function_that_does_nothing()
>>> nothing.__eq__(None)
True

In most common cases the outcome will be the same, but the __eq__() method opens a door that voids any guarantee of accuracy, since it can be overridden in a class to provide special behavior.

Consider this class.

>>> class Empty(object):
...     def __eq__(self, other):
...         return not other

So you try it on None and it works

>>> empty = Empty()
>>> empty==None
True

But then it also works on the empty string

>>> empty==''
True

And yet

>>> ''==None
False
>>> empty is None
False

Case 2: Using None as a boolean

The following two tests

if value:
    # Do something

if not value:
    # Do something

are in fact evaluated as

if bool(value):
    # Do something

if not bool(value):
    # Do something

None is a "falsey", meaning that if cast to a boolean it will return False and if applied the not operator it will return True. Note however that it's not a property unique to None. In addition to False itself, the property is shared by empty lists, tuples, sets, dicts, strings, as well as 0, and all objects from classes that implement the __bool__() magic method to return False.

>>> bool(None)
False
>>> not None
True

>>> bool([])
False
>>> not []
True

>>> class MyFalsey(object):
...     def __bool__(self):
...         return False
>>> f = MyFalsey()
>>> bool(f)
False
>>> not f
True

So when testing for variables in the following way, be extra aware of what you're including or excluding from the test:

def some_function(value=None):
    if not value:
        value = init_value()

In the above, did you mean to call init_value() when the value is set specifically to None, or did you mean that a value set to 0, or the empty string, or an empty list should also trigger the initialization? Like I said, be mindful. As it's often the case, in Python explicit is better than implicit.

None in practice

None used as a signal value

None has a special status in Python. It's a favorite baseline value because many algorithms treat it as an exceptional value. In such scenarios it can be used as a flag to signal that a condition requires some special handling (such as the setting of a default value).

You can assign None to the keyword arguments of a function and then explicitly test for it.

def my_function(value, param=None):
    if param is None:
        # Do something outrageous!

You can return it as the default when trying to get to an object's attribute and then explicitly test for it before doing something special.

value = getattr(some_obj, 'some_attribute', None)
if value is None:
    # do something spectacular!

By default a dictionary's get() method returns None when trying to access a non-existing key:

>>> some_dict = {}
>>> value = some_dict.get('foo')
>>> value is None
True

If you were to try to access it by using the subscript notation a KeyError would be raised

>>> value = some_dict['foo']
KeyError: 'foo'

Likewise if you attempt to pop a non-existing item

>>> value = some_dict.pop('foo')
KeyError: 'foo'

which you can suppress with a default value that is usually set to None

value = some_dict.pop('foo', None)
if value is None:
    # Booom!

None used as both a flag and valid value

The above described uses of None apply when it is not considered a valid value, but more like a signal to do something special. There are situations however where it sometimes matters to know where None came from because even though it's used as a signal it could also be part of the data.

When you query an object for its attribute with getattr(some_obj, 'attribute_name', None) getting back None doesn't tell you if the attribute you were trying to access was set to None or if it was altogether absent from the object. The same situation when accessing a key from a dictionary, like some_dict.get('some_key'), you don't know if some_dict['some_key'] is missing or if it's just set to None. If you need that information, the usual way to handle this is to directly attempt accessing the attribute or key from within a try/except construct:

try:
    # Equivalent to getattr() without specifying a default
    # value = getattr(some_obj, 'some_attribute')
    value = some_obj.some_attribute
    # Now you handle `None` the data here
    if value is None:
        # Do something here because the attribute was set to None
except AttributeError:
    # We're now handling the exceptional situation from here.
    # We could assign None as a default value if required.
    value = None
    # In addition, since we now know that some_obj doesn't have the
    # attribute 'some_attribute' we could do something about that.
    log_something(some_obj)

Similarly with dict:

try:
    value = some_dict['some_key']
    if value is None:
        # Do something here because 'some_key' is set to None
except KeyError:
    # Set a default
    value = None
    # And do something because 'some_key' was missing
    # from the dict.
    log_something(some_dict)

The above two examples show how to handle object and dictionary cases. What about functions? The same thing, but we use the double asterisks keyword argument to that end:

def my_function(**kwargs):
    try:
        value = kwargs['some_key']
        if value is None:
            # Do something because 'some_key' is explicitly
            # set to None
    except KeyError:
        # We assign the default
        value = None
        # And since it's not coming from the caller.
        log_something('did not receive "some_key"')

None used only as a valid value

If you find that your code is littered with the above try/except pattern simply to differentiate between None flags and None data, then just use another test value. There's a pattern where a value that falls outside the set of valid values is inserted as part of the data in a data structure and is used to control and test special conditions (e.g. boundaries, state, etc.). Such a value is called a sentinel and it can be used the way None is used as a signal. It's trivial to create a sentinel in Python.

undefined = object()

The undefined object above is unique and doesn't do much of anything that might be of interest to a program, it's thus an excellent replacement for None as a flag. Some caveats apply, more about that after the code.

With function

def my_function(value, param1=undefined, param2=undefined):
    if param1 is undefined:
        # We know nothing was passed to it, not even None
        log_something('param1 was missing')
        param1 = None


    if param2 is undefined:
        # We got nothing here either
        log_something('param2 was missing')
        param2 = None

With dict

value = some_dict.get('some_key', undefined)
if value is None:
    log_something("'some_key' was set to None")

if value is undefined:
    # We know that the dict didn't have 'some_key'
    log_something("'some_key' was not set at all")
    value = None

With an object

value = getattr(obj, 'some_attribute', undefined)
if value is None:
    log_something("'obj.some_attribute' was set to None")
if value is undefined:
    # We know that there's no obj.some_attribute
    log_something("no 'some_attribute' set on obj")
    value = None

As I mentioned earlier, custom sentinels come with some caveats. First, they're not keywords like None, so Python doesn't protect them. You can overwrite your undefined above at any time, anywhere in the module it's defined, so be careful how you expose and use them. Next, the instance returned by object() is not a singleton. If you make that call 10 times you get 10 different objects. Finally, usage of a sentinel is highly idiosyncratic. A sentinel is specific to the library it's used in and as such its scope should generally be limited to the library's internals. It shouldn't "leak" out. External code should only become aware of it, if their purpose is to extend or supplement the library's API.

Bootstrap 4 - Inline List?

Bootstrap4

Remove a list’s bullets and apply some light margin with a combination of two classes, .list-inline and .list-inline-item.

<ul class="list-inline">
   <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">FB</a></li>
   <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">G+</a></li>
   <li class="list-inline-item"><a class="social-icon text-xs-center" target="_blank" href="#">T</a></li>
</ul>

List all kafka topics

Please use kafka-topics.sh --list --bootstrap-server localhost:9092 to list down all topics

What's is the difference between include and extend in use case diagram?

Extends is used when you understand that your use case is too much complex. So you extract the complex steps into their own "extension" use cases.

Includes is used when you see common behavior in two use cases. So you abstract out the common behavior into a separate "abstract" use case.

(ref: Jeffrey L. Whitten, Lonnie D. Bentley, Systems analysis & design methods, McGraw-Hill/Irwin, 2007)

Hibernate vs JPA vs JDO - pros and cons of each?

I am using JPA (OpenJPA implementation from Apache which is based on the KODO JDO codebase which is 5+ years old and extremely fast/reliable). IMHO anyone who tells you to bypass the specs is giving you bad advice. I put the time in and was definitely rewarded. With either JDO or JPA you can change vendors with minimal changes (JPA has orm mapping so we are talking less than a day to possibly change vendors). If you have 100+ tables like I do this is huge. Plus you get built0in caching with cluster-wise cache evictions and its all good. SQL/Jdbc is fine for high performance queries but transparent persistence is far superior for writing your algorithms and data input routines. I only have about 16 SQL queries in my whole system (50k+ lines of code).

Difference between Constructor and ngOnInit

The above answers don't really answer this aspect of the original question: What is a lifecycle hook? It took me a while to understand what that means until I thought of it this way.

1) Say your component is a human. Humans have lives that include many stages of living, and then we expire.

2) Our human component could have the following lifecycle script: Born, Baby, Grade School, Young Adult, Mid-age Adult, Senior Adult, Dead, Disposed of.

3) Say you want to have a function to create children. To keep this from getting complicated, and rather humorous, you want your function to only be called during the Young Adult stage of the human component life. So you develop a component that is only active when the parent component is in the Young Adult stage. Hooks help you do that by signaling that stage of life and letting your component act on it.

Fun stuff. If you let your imagination go to actually coding something like this it gets complicated, and funny.

PHP Multiple Checkbox Array

Also remember you can include custom indices to the array sent to the server like this

<form method='post' id='userform' action='thisform.php'>
<tr>
    <td>Trouble Type</td>
    <td>
    <input type='checkbox' name='checkboxvar[4]' value='Option One'>4<br>
    <input type='checkbox' name='checkboxvar[6]' value='Option Two'>6<br>
    <input type='checkbox' name='checkboxvar[9]' value='Option Three'>9
    </td>
</tr>
<input type='submit' class='buttons'>
</form>

This is particularly useful when you want to use the id of individual objects in a server array accounts (for instance) to send data back to the server and recognize same at server

<form method='post' id='userform' action='thisform.php'>
<tr>
    <td>Trouble Type</td>
    <td>
    <?php foreach($accounts as $account) { ?>
        <input type='checkbox' name='accounts[<?php echo $account->id ?>]' value='<?php echo $account->name ?>'>
        <?php echo $account->name ?>
        <br>
    <?php } ?>
    </td>
</tr>
<input type='submit' class='buttons'>
</form>

<?php 
if (isset($_POST['accounts'])) 
{
    print_r($_POST['accounts']); 
}
?>

C# Enum - How to Compare Value

You can use extension methods to do the same thing with less code.

public enum AccountType
{
    Retailer = 1,
    Customer = 2,
    Manager = 3,
    Employee = 4
}

static class AccountTypeMethods
{
    public static bool IsRetailer(this AccountType ac)
    {
        return ac == AccountType.Retailer;
    }
}

And to use:

if (userProfile.AccountType.isRetailer())
{
    //your code
}

I would recommend to rename the AccountType to Account. It's not a name convention.

How do I grep for all non-ASCII characters?

The easy way is to define a non-ASCII character... as a character that is not an ASCII character.

LC_ALL=C grep '[^ -~]' file.xml

Add a tab after the ^ if necessary.

Setting LC_COLLATE=C avoids nasty surprises about the meaning of character ranges in many locales. Setting LC_CTYPE=C is necessary to match single-byte characters — otherwise the command would miss invalid byte sequences in the current encoding. Setting LC_ALL=C avoids locale-dependent effects altogether.

Is it possible to auto-format your code in Dreamweaver?

And for JavaScript source format you can use Dreamweaver JavaScript source formatting extension.(available on adobe)

How do I get a list of folders and sub folders without the files?

I am using this from PowerShell:

dir -directory -name -recurse > list_my_folders.txt

How do I give text or an image a transparent background using CSS?

Here is a jQuery plugin that will handle everything for you, Transify (Transify - a jQuery plugin to easily apply transparency / opacity to an element’s background).

I was running into this problem every now and then, so I decided to write something that would make life a lot easier. The script is less than 2 KB and it only requires one line of code to get it to work, and it will also handle animating the opacity of the background if you like.

Using Transactions or SaveChanges(false) and AcceptAllChanges()?

If you are using EF6 (Entity Framework 6+), this has changed for database calls to SQL.
See: http://msdn.microsoft.com/en-us/data/dn456843.aspx

use context.Database.BeginTransaction.

From MSDN:

using (var context = new BloggingContext()) 
{ 
    using (var dbContextTransaction = context.Database.BeginTransaction()) 
    { 
        try 
        { 
            context.Database.ExecuteSqlCommand( 
                @"UPDATE Blogs SET Rating = 5" + 
                    " WHERE Name LIKE '%Entity Framework%'" 
                ); 

            var query = context.Posts.Where(p => p.Blog.Rating >= 5); 
            foreach (var post in query) 
            { 
                post.Title += "[Cool Blog]"; 
            } 

            context.SaveChanges(); 

            dbContextTransaction.Commit(); 
        } 
        catch (Exception) 
        { 
            dbContextTransaction.Rollback(); //Required according to MSDN article 
            throw; //Not in MSDN article, but recommended so the exception still bubbles up
        } 
    } 
} 

The character encoding of the HTML document was not declared

Add this as a first line in the HEAD section of your HTML template

<meta content="text/html;charset=utf-8" http-equiv="Content-Type">
<meta content="utf-8" http-equiv="encoding">

Find Process Name by its Process ID

@ECHO OFF
SETLOCAL ENABLEDELAYEDEXPANSION
SET /a pid=1600
FOR /f "skip=3delims=" %%a IN ('tasklist') DO (
 SET "found=%%a"
 SET /a foundpid=!found:~26,8!
 IF %pid%==!foundpid! echo found %pid%=!found:~0,24%!
)

GOTO :EOF

...set PID to suit your circumstance.

Constructor overload in TypeScript

Update 2 (28 September 2020): This language is constantly evolving, and so if you can use Partial (introduced in v2.1) then this is now my preferred way to achieve this.

class Box {
   x: number;
   y: number;
   height: number;
   width: number;

   public constructor(b: Partial<Box> = {}) {
      Object.assign(this, b);
   }
}

// Example use
const a = new Box();
const b = new Box({x: 10, height: 99});
const c = new Box({foo: 10});          // Will fail to compile

Update (8 June 2017): guyarad and snolflake make valid points in their comments below to my answer. I would recommend readers look at the answers by Benson, Joe and snolflake who have better answers than mine.*

Original Answer (27 January 2014)

Another example of how to achieve constructor overloading:

class DateHour {

  private date: Date;
  private relativeHour: number;

  constructor(year: number, month: number, day: number, relativeHour: number);
  constructor(date: Date, relativeHour: number);
  constructor(dateOrYear: any, monthOrRelativeHour: number, day?: number, relativeHour?: number) {
    if (typeof dateOrYear === "number") {
      this.date = new Date(dateOrYear, monthOrRelativeHour, day);
      this.relativeHour = relativeHour;
    } else {
      var date = <Date> dateOrYear;
      this.date = new Date(date.getFullYear(), date.getMonth(), date.getDate());
      this.relativeHour = monthOrRelativeHour;
    }
  }
}

Source: http://mimosite.com/blog/post/2013/04/08/Overloading-in-TypeScript

'const int' vs. 'int const' as function parameters in C++ and C

const T and T const are identical. With pointer types it becomes more complicated:

  1. const char* is a pointer to a constant char
  2. char const* is a pointer to a constant char
  3. char* const is a constant pointer to a (mutable) char

In other words, (1) and (2) are identical. The only way of making the pointer (rather than the pointee) const is to use a suffix-const.

This is why many people prefer to always put const to the right side of the type (“East const” style): it makes its location relative to the type consistent and easy to remember (it also anecdotally seems to make it easier to teach to beginners).

Download image from the site in .NET/C#

Also possible to use DownloadData method

    private byte[] GetImage(string iconPath)
    {
        using (WebClient client = new WebClient())
        {
            byte[] pic = client.DownloadData(iconPath);
            //string checkPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) +@"\1.png";
            //File.WriteAllBytes(checkPath, pic);
            return pic;
        }
    }

how to get curl to output only http response body (json) and no other headers etc

You are specifying the -i option:

-i, --include

(HTTP) Include the HTTP-header in the output. The HTTP-header includes things like server-name, date of the document, HTTP-version and more...

Simply remove that option from your command line:

response=$(curl -sb -H "Accept: application/json" "http://host:8080/some/resource")

Python initializing a list of lists

The problem is that they're all the same exact list in memory. When you use the [x]*n syntax, what you get is a list of n many x objects, but they're all references to the same object. They're not distinct instances, rather, just n references to the same instance.

To make a list of 3 different lists, do this:

x = [[] for i in range(3)]

This gives you 3 separate instances of [], which is what you want

[[]]*n is similar to

l = []
x = []
for i in range(n):
    x.append(l)

While [[] for i in range(3)] is similar to:

x = []
for i in range(n):
    x.append([])   # appending a new list!

In [20]: x = [[]] * 4

In [21]: [id(i) for i in x]
Out[21]: [164363948, 164363948, 164363948, 164363948] # same id()'s for each list,i.e same object


In [22]: x=[[] for i in range(4)]

In [23]: [id(i) for i in x]
Out[23]: [164382060, 164364140, 164363628, 164381292] #different id(), i.e unique objects this time

Regular expression to find two strings anywhere in input

This is fairly easy on processing power required:

(string1(.|\n)*string2)|(string2(.|\n)*string1)

I used this in visual studio 2013 to find all files that had both string 1 and 2 in it.

Improve INSERT-per-second performance of SQLite

The answer to your question is that the newer SQLite 3 has improved performance, use that.

This answer Why is SQLAlchemy insert with sqlite 25 times slower than using sqlite3 directly? by SqlAlchemy Orm Author has 100k inserts in 0.5 sec, and I have seen similar results with python-sqlite and SqlAlchemy. Which leads me to believe that performance has improved with SQLite 3.

How do I build an import library (.lib) AND a DLL in Visual C++?

By selecting 'Class Library' you were accidentally telling it to make a .Net Library using the CLI (managed) extenstion of C++.

Instead, create a Win32 project, and in the Application Settings on the next page, choose 'DLL'.

You can also make an MFC DLL or ATL DLL from those library choices if you want to go that route, but it sounds like you don't.

How to execute a shell script from C in Linux?

If you're ok with POSIX, you can also use popen()/pclose()

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

int main(void) {
/* ls -al | grep '^d' */
  FILE *pp;
  pp = popen("ls -al", "r");
  if (pp != NULL) {
    while (1) {
      char *line;
      char buf[1000];
      line = fgets(buf, sizeof buf, pp);
      if (line == NULL) break;
      if (line[0] == 'd') printf("%s", line); /* line includes '\n' */
    }
    pclose(pp);
  }
  return 0;
}

C++ Remove new line from multiline string

Another way to do it in the for loop

void rm_nl(string &s) {
    for (int p = s.find("\n"); p != (int) string::npos; p = s.find("\n"))
    s.erase(p,1);
}

Usage:

string data = "\naaa\nbbb\nccc\nddd\n";
rm_nl(data); 
cout << data; // data = aaabbbcccddd

Check the current number of connections to MongoDb

You can just use

db.serverStatus().connections

Also, this function can help you spot the IP addresses connected to your Mongo DB

db.currentOp(true).inprog.forEach(function(x) { print(x.client) })

Difference between @Mock and @InjectMocks

One advantage you get with the approach mentioned by @Tom is that you don't have to create any constructors in the SomeManager, and hence limiting the clients to instantiate it.

@RunWith(MockitoJUnitRunner.class)
public class SomeManagerTest {

    @InjectMocks
    private SomeManager someManager;

    @Mock
    private SomeDependency someDependency; // this will be injected into someManager

    //You don't need to instantiate the SomeManager with default contructor at all
   //SomeManager someManager = new SomeManager();    
   //Or SomeManager someManager = new SomeManager(someDependency);

     //tests...

}

Whether its a good practice or not depends on your application design.

Start HTML5 video at a particular position when loading?

Using a #t=10,20 fragment worked for me.

React Modifying Textarea Values

As a newbie in React world, I came across a similar issues where I could not edit the textarea and struggled with binding. It's worth knowing about controlled and uncontrolled elements when it comes to react.

The value of the following uncontrolled textarea cannot be changed because of value

 <textarea type="text" value="some value"
    onChange={(event) => this.handleOnChange(event)}></textarea>

The value of the following uncontrolled textarea can be changed because of use of defaultValue or no value attribute

<textarea type="text" defaultValue="sample" 
    onChange={(event) => this.handleOnChange(event)}></textarea>

<textarea type="text" 
   onChange={(event) => this.handleOnChange(event)}></textarea>

The value of the following controlled textarea can be changed because of how value is mapped to a state as well as the onChange event listener

<textarea value={this.state.textareaValue} 
onChange={(event) => this.handleOnChange(event)}></textarea>

Here is my solution using different syntax. I prefer the auto-bind than manual binding however, if I were to not use {(event) => this.onXXXX(event)} then that would cause the content of textarea to be not editable OR the event.preventDefault() does not work as expected. Still a lot to learn I suppose.

class Editor extends React.Component {
  constructor(props) {
    super(props)
    this.state = {
      textareaValue: ''
    }
  }
  handleOnChange(event) {
    this.setState({
      textareaValue: event.target.value
    })
  }
  handleOnSubmit(event) {
    event.preventDefault();
    this.setState({
      textareaValue: this.state.textareaValue + ' [Saved on ' + (new Date()).toLocaleString() + ']'
    })
  }
  render() {
    return <div>
        <form onSubmit={(event) => this.handleOnSubmit(event)}>
          <textarea rows={10} cols={30} value={this.state.textareaValue} 
            onChange={(event) => this.handleOnChange(event)}></textarea>
          <br/>
          <input type="submit" value="Save"/>
        </form>
      </div>
  }
}
ReactDOM.render(<Editor />, document.getElementById("content"));

The versions of libraries are

"babel-cli": "6.24.1",
"babel-preset-react": "6.24.1"
"React & ReactDOM v15.5.4" 

jQuery animate scroll

You can animate the scrolltop of the page with jQuery.

$('html, body').animate({
    scrollTop: $(".middle").offset().top
 }, 2000);

See this site: http://papermashup.com/jquery-page-scrolling/

Extract year from date

When you convert your variable to Date:

date <-  as.Date('10/30/2018','%m/%d/%Y')

you can then cut out the elements you want and make new variables, like year:

year <- as.numeric(format(date,'%Y'))

or month:

month <- as.numeric(format(date,'%m'))

How to specify non-default shared-library path in GCC Linux? Getting "error while loading shared libraries" when running

Should it be LIBRARY_PATH instead of LD_LIBRARY_PATH. gcc checks for LIBRARY_PATH which can be seen with -v option

Get the _id of inserted document in Mongo database in NodeJS

if you want to take "_id" use simpley

result.insertedId.toString() 

// toString will convert from hex

Dynamic type languages versus static type languages

It depends on context. There a lot benefits that are appropriate to dynamic typed system as well as for strong typed. I'm of opinion that the flow of dynamic types language is faster. The dynamic languages are not constrained with class attributes and compiler thinking of what is going on in code. You have some kinda freedom. Furthermore, the dynamic language usually is more expressive and result in less code which is good. Despite of this, it's more error prone which is also questionable and depends more on unit test covering. It's easy prototype with dynamic lang but maintenance may become nightmare.

The main gain over static typed system is IDE support and surely static analyzer of code. You become more confident of code after every code change. The maintenance is peace of cake with such tools.

Laravel Escaping All HTML in Blade Template

use this tag {!! description text !!}

Javascript Date Validation ( DD/MM/YYYY) & Age Checking

with leading zero for day and month

var pattern =/^(0[1-9]|1[0-9]|2[0-9]|3[0-1])\/(0[1-9]|1[0-2])\/([0-9]{4})$/;

and with both leading zero/without leading zero for day and month

var pattern =/^(0?[1-9]|1[0-9]|2[0-9]|3[0-1])\/(0?[1-9]|1[0-2])\/([0-9]{4})$/;

What do <o:p> elements do anyway?

Couldn't find any official documentation (no surprise there) but according to this interesting article, those elements are injected in order to enable Word to convert the HTML back to fully compatible Word document, with everything preserved.

The relevant paragraph:

Microsoft added the special tags to Word's HTML with an eye toward backward compatibility. Microsoft wanted you to be able to save files in HTML complete with all of the tracking, comments, formatting, and other special Word features found in traditional DOC files. If you save a file in HTML and then reload it in Word, theoretically you don't loose anything at all.

This makes lots of sense.

For your specific question.. the o in the <o:p> means "Office namespace" so anything following the o: in a tag means "I'm part of Office namespace" - in case of <o:p> it just means paragraph, the equivalent of the ordinary <p> tag.

I assume that every HTML tag has its Office "equivalent" and they have more.

How to check if a file exists in the Documents directory in Swift?

Swift 4 example:

var filePath: String {
    //manager lets you examine contents of a files and folders in your app.
    let manager = FileManager.default

    //returns an array of urls from our documentDirectory and we take the first
    let url = manager.urls(for: .documentDirectory, in: .userDomainMask).first
    //print("this is the url path in the document directory \(String(describing: url))")

    //creates a new path component and creates a new file called "Data" where we store our data array
    return(url!.appendingPathComponent("Data").path)
}

I put the check in my loadData function which I called in viewDidLoad.

override func viewDidLoad() {
    super.viewDidLoad()

    loadData()
}

Then I defined loadData below.

func loadData() {
    let manager = FileManager.default

    if manager.fileExists(atPath: filePath) {
        print("The file exists!")

        //Do what you need with the file. 
        ourData = NSKeyedUnarchiver.unarchiveObject(withFile: filePath) as! Array<DataObject>         
    } else {
        print("The file DOES NOT exist! Mournful trumpets sound...")
    }
}

How to list files and folder in a dir (PHP)

//path to directory to scan
$directory = "../data/team/";

//get all text files with a .txt extension.
$texts = glob($directory . "*.txt");

//print each file name
foreach($texts as $text)
{
    echo $text;
}

How to have Android Service communicate with Activity

There are three obvious ways to communicate with services:

  1. Using Intents
  2. Using AIDL
  3. Using the service object itself (as singleton)

In your case, I'd go with option 3. Make a static reference to the service it self and populate it in onCreate():

void onCreate(Intent i) {
  sInstance = this;
}

Make a static function MyService getInstance(), which returns the static sInstance.

Then in Activity.onCreate() you start the service, asynchronously wait until the service is actually started (you could have your service notify your app it's ready by sending an intent to the activity.) and get its instance. When you have the instance, register your service listener object to you service and you are set. NOTE: when editing Views inside the Activity you should modify them in the UI thread, the service will probably run its own Thread, so you need to call Activity.runOnUiThread().

The last thing you need to do is to remove the reference to you listener object in Activity.onPause(), otherwise an instance of your activity context will leak, not good.

NOTE: This method is only useful when your application/Activity/task is the only process that will access your service. If this is not the case you have to use option 1. or 2.

Twig ternary operator, Shorthand if-then-else

You can use shorthand syntax as of Twig 1.12.0

{{ foo ?: 'no' }} is the same as {{ foo ? foo : 'no' }}
{{ foo ? 'yes' }} is the same as {{ foo ? 'yes' : '' }}

How can I start and check my MySQL log?

Seems like the general query log is the file that you need. A good introduction to this is at http://dev.mysql.com/doc/refman/5.1/en/query-log.html

How to test if a string contains one of the substrings in a list, in pandas?

Here is a one line lambda that also works:

df["TrueFalse"] = df['col1'].apply(lambda x: 1 if any(i in x for i in searchfor) else 0)

Input:

searchfor = ['og', 'at']

df = pd.DataFrame([('cat', 1000.0), ('hat', 2000000.0), ('dog', 1000.0), ('fog', 330000.0),('pet', 330000.0)], columns=['col1', 'col2'])

   col1  col2
0   cat 1000.0
1   hat 2000000.0
2   dog 1000.0
3   fog 330000.0
4   pet 330000.0

Apply Lambda:

df["TrueFalse"] = df['col1'].apply(lambda x: 1 if any(i in x for i in searchfor) else 0)

Output:

    col1    col2        TrueFalse
0   cat     1000.0      1
1   hat     2000000.0   1
2   dog     1000.0      1
3   fog     330000.0    1
4   pet     330000.0    0

How do I exit the Vim editor?

I got Vim by installing a Git client on Windows. :q wouldn't exit Vim for me. :exit did however...

How do I get values from a SQL database into textboxes using C#?

using (SqlConnection connection =  new SqlConnection("Data Source=localhost;Initial Catalog=LoginScreen;Integrated Security=True"))
{
    SqlCommand command =
    new SqlCommand("select * from Pending_Tasks WHERE CustomerId=...", connection);
    connection.Open();

    SqlDataReader read= command.ExecuteReader();

    while (read.Read())
    {
        CustID.Text = (read["Customer_ID"].ToString());
        CustName.Text = (read["Customer_Name"].ToString());
        Add1.Text = (read["Address_1"].ToString());
        Add2.Text = (read["Address_2"].ToString());
        PostBox.Text = (read["Postcode"].ToString());
        PassBox.Text = (read["Password"].ToString());
        DatBox.Text = (read["Data_Important"].ToString());
        LanNumb.Text = (read["Landline"].ToString());
        MobNumber.Text = (read["Mobile"].ToString());
        FaultRep.Text = (read["Fault_Report"].ToString());
    }
    read.Close();
}

Make sure you have data in the query : select * from Pending_Tasks and you are using "using System.Data.SqlClient;"

"’" showing on page instead of " ' "

(Unicode codepoint U+2019 RIGHT SINGLE QUOTATION MARK) is encoded in UTF-8 as bytes:

0xE2 0x80 0x99.

’ (Unicode codepoints U+00E2 U+20AC U+2122) is encoded in UTF-8 as bytes:

0xC3 0xA2   0xE2 0x82 0xAC   0xE2 0x84 0xA2.

These are the bytes your browser is actually receiving in order to produce ’ when processed as UTF-8.

That means that your source data is going through two charset conversions before being sent to the browser:

  1. The source character (U+2019) is first encoded as UTF-8 bytes:

    0xE2 0x80 0x99

  2. those individual bytes were then being mis-interpreted and decoded to Unicode codepoints U+00E2 U+20AC U+2122 by one of the Windows-125X charsets (1252, 1254, 1256, and 1258 all map 0xE2 0x80 0x99 to U+00E2 U+20AC U+2122), and then those codepoints are being encoded as UTF-8 bytes:

    0xE2 -> U+00E2 -> 0xC3 0xA2
    0x80 -> U+20AC -> 0xE2 0x82 0xAC
    0x99 -> U+2122 -> 0xE2 0x84 0xA2

You need to find where the extra conversion in step 2 is being performed and remove it.

Simple way to unzip a .zip file using zlib

Minizip does have an example programs to demonstrate its usage - the files are called minizip.c and miniunz.c.

Update: I had a few minutes so I whipped up this quick, bare bones example for you. It's very smelly C, and I wouldn't use it without major improvements. Hopefully it's enough to get you going for now.

// uzip.c - Simple example of using the minizip API.
// Do not use this code as is! It is educational only, and probably
// riddled with errors and leaks!
#include <stdio.h>
#include <string.h>

#include "unzip.h"

#define dir_delimter '/'
#define MAX_FILENAME 512
#define READ_SIZE 8192

int main( int argc, char **argv )
{
    if ( argc < 2 )
    {
        printf( "usage:\n%s {file to unzip}\n", argv[ 0 ] );
        return -1;
    }

    // Open the zip file
    unzFile *zipfile = unzOpen( argv[ 1 ] );
    if ( zipfile == NULL )
    {
        printf( "%s: not found\n" );
        return -1;
    }

    // Get info about the zip file
    unz_global_info global_info;
    if ( unzGetGlobalInfo( zipfile, &global_info ) != UNZ_OK )
    {
        printf( "could not read file global info\n" );
        unzClose( zipfile );
        return -1;
    }

    // Buffer to hold data read from the zip file.
    char read_buffer[ READ_SIZE ];

    // Loop to extract all files
    uLong i;
    for ( i = 0; i < global_info.number_entry; ++i )
    {
        // Get info about current file.
        unz_file_info file_info;
        char filename[ MAX_FILENAME ];
        if ( unzGetCurrentFileInfo(
            zipfile,
            &file_info,
            filename,
            MAX_FILENAME,
            NULL, 0, NULL, 0 ) != UNZ_OK )
        {
            printf( "could not read file info\n" );
            unzClose( zipfile );
            return -1;
        }

        // Check if this entry is a directory or file.
        const size_t filename_length = strlen( filename );
        if ( filename[ filename_length-1 ] == dir_delimter )
        {
            // Entry is a directory, so create it.
            printf( "dir:%s\n", filename );
            mkdir( filename );
        }
        else
        {
            // Entry is a file, so extract it.
            printf( "file:%s\n", filename );
            if ( unzOpenCurrentFile( zipfile ) != UNZ_OK )
            {
                printf( "could not open file\n" );
                unzClose( zipfile );
                return -1;
            }

            // Open a file to write out the data.
            FILE *out = fopen( filename, "wb" );
            if ( out == NULL )
            {
                printf( "could not open destination file\n" );
                unzCloseCurrentFile( zipfile );
                unzClose( zipfile );
                return -1;
            }

            int error = UNZ_OK;
            do    
            {
                error = unzReadCurrentFile( zipfile, read_buffer, READ_SIZE );
                if ( error < 0 )
                {
                    printf( "error %d\n", error );
                    unzCloseCurrentFile( zipfile );
                    unzClose( zipfile );
                    return -1;
                }

                // Write data to file.
                if ( error > 0 )
                {
                    fwrite( read_buffer, error, 1, out ); // You should check return of fwrite...
                }
            } while ( error > 0 );

            fclose( out );
        }

        unzCloseCurrentFile( zipfile );

        // Go the the next entry listed in the zip file.
        if ( ( i+1 ) < global_info.number_entry )
        {
            if ( unzGoToNextFile( zipfile ) != UNZ_OK )
            {
                printf( "cound not read next file\n" );
                unzClose( zipfile );
                return -1;
            }
        }
    }

    unzClose( zipfile );

    return 0;
}

I built and tested it with MinGW/MSYS on Windows like this:

contrib/minizip/$ gcc -I../.. -o unzip uzip.c unzip.c ioapi.c ../../libz.a
contrib/minizip/$ ./unzip.exe /j/zlib-125.zip

Install IPA with iTunes 12

Note : If you are using iTunes 12.7.0 or above then use Solution 2 else use Solution 1. Solution 1 cannot be used with iTunes 12.7.0 or above since Apps section has been removed from iTunes by Apple

Solution 1 : Using iTunes 12.7 below

Tested on iTunes 12 with Mac OS X (Yosemite) 10.10.3

Also, tested on iTunes 12.3.2.35 with Mac OX X (El Capitan) 10.11.3

This process also applicable for iTunes 12.5.5 with Mac OS X (macOS Sierra) 10.12.3.

You can install IPA file using iTunes 12.x onto device using below steps :

  1. Drag-and-drop IPA file into 'Apps' tab of iTunes BEFORE you connect the device.
  2. Connect your device
  3. Select your device on iTunes
  4. Select 'Apps' tab

Screenshot for step 3 and 4

  1. Search app that you want to install

Screenshot for step 5

  1. Click on 'Install' button. This will change to 'Will Install'

Screenshot for step 6

  1. Click on 'Apply' button on right corner. This will initiate process of app installation. You can see status on top of iTunes as well as app on device.

Screenshot for step 7

Screenshot for step 7

  1. You can allow new apps to install automatically by enabling checkmark present at bottom.

Screenshot for step 8

Solution 2 : Using iTunes 12.7 and above

You can use diawi for this purpose.

  1. Open https://www.diawi.com/ in desktop/system browser

Step1

  1. Drag-and-drop IPA file in empty window. Make sure that last check mark are unselected (recommended due to security concern)

  2. Once the upload is completed then press Send button

Step2-3

  1. This will generate a link and QR code as well. (You can share this link and QR code with Client)

Step4

  1. Now open Safari browser in iPhone device and enter this link (Note that link is case-sensitive) OR You can scan the QR using Bakodo iOS app

Step5

  1. Once link is loaded you can see app details

  2. Now select ‘Install application

Step 6-7

  1. This will prompt an alert asking permission for installation. Press on Install.

Step 8

  1. Now you can see the app installation begins on screen.

Step 9

Perl - If string contains text?

If you just need to search for one string within another, use the index function (or rindex if you want to start scanning from the end of the string):

if (index($string, $substring) != -1) {
   print "'$string' contains '$substring'\n";
}

To search a string for a pattern match, use the match operator m//:

if ($string =~ m/pattern/) {
    print "'$string' matches the pattern\n";       
}

Python try-else

try:
    statements # statements that can raise exceptions
except:
    statements # statements that will be executed to handle exceptions
else:
    statements # statements that will be executed if there is no exception

Example :

try:
    age=int(input('Enter your age: '))
except:
    print ('You have entered an invalid value.')
else:
    if age <= 21:
        print('You are not allowed to enter, you are too young.')
    else:
        print('Welcome, you are old enough.')

The Output :

>>> 
Enter your age: a
You have entered an invalid value.
>>> RESTART
>>> 
Enter your age: 25
Welcome, you are old enough.
>>>RESTART
>>> 
Enter your age: 13
You are not allowed to enter, you are too young.
>>>

Copied from : https://geek-university.com/python/the-try-except-else-statements/

How to enable CORS on Firefox?

It's only possible when the server sends this header: Access-Control-Allow-Origin: *

If this is your code then you can setup it like this (PHP):

header('Access-Control-Allow-Origin: *');

PostgreSQL return result set as JSON array?

TL;DR

SELECT json_agg(t) FROM t

for a JSON array of objects, and

SELECT
    json_build_object(
        'a', json_agg(t.a),
        'b', json_agg(t.b)
    )
FROM t

for a JSON object of arrays.

List of objects

This section describes how to generate a JSON array of objects, with each row being converted to a single object. The result looks like this:

[{"a":1,"b":"value1"},{"a":2,"b":"value2"},{"a":3,"b":"value3"}]

9.3 and up

The json_agg function produces this result out of the box. It automatically figures out how to convert its input into JSON and aggregates it into an array.

SELECT json_agg(t) FROM t

There is no jsonb (introduced in 9.4) version of json_agg. You can either aggregate the rows into an array and then convert them:

SELECT to_jsonb(array_agg(t)) FROM t

or combine json_agg with a cast:

SELECT json_agg(t)::jsonb FROM t

My testing suggests that aggregating them into an array first is a little faster. I suspect that this is because the cast has to parse the entire JSON result.

9.2

9.2 does not have the json_agg or to_json functions, so you need to use the older array_to_json:

SELECT array_to_json(array_agg(t)) FROM t

You can optionally include a row_to_json call in the query:

SELECT array_to_json(array_agg(row_to_json(t))) FROM t

This converts each row to a JSON object, aggregates the JSON objects as an array, and then converts the array to a JSON array.

I wasn't able to discern any significant performance difference between the two.

Object of lists

This section describes how to generate a JSON object, with each key being a column in the table and each value being an array of the values of the column. It's the result that looks like this:

{"a":[1,2,3], "b":["value1","value2","value3"]}

9.5 and up

We can leverage the json_build_object function:

SELECT
    json_build_object(
        'a', json_agg(t.a),
        'b', json_agg(t.b)
    )
FROM t

You can also aggregate the columns, creating a single row, and then convert that into an object:

SELECT to_json(r)
FROM (
    SELECT
        json_agg(t.a) AS a,
        json_agg(t.b) AS b
    FROM t
) r

Note that aliasing the arrays is absolutely required to ensure that the object has the desired names.

Which one is clearer is a matter of opinion. If using the json_build_object function, I highly recommend putting one key/value pair on a line to improve readability.

You could also use array_agg in place of json_agg, but my testing indicates that json_agg is slightly faster.

There is no jsonb version of the json_build_object function. You can aggregate into a single row and convert:

SELECT to_jsonb(r)
FROM (
    SELECT
        array_agg(t.a) AS a,
        array_agg(t.b) AS b
    FROM t
) r

Unlike the other queries for this kind of result, array_agg seems to be a little faster when using to_jsonb. I suspect this is due to overhead parsing and validating the JSON result of json_agg.

Or you can use an explicit cast:

SELECT
    json_build_object(
        'a', json_agg(t.a),
        'b', json_agg(t.b)
    )::jsonb
FROM t

The to_jsonb version allows you to avoid the cast and is faster, according to my testing; again, I suspect this is due to overhead of parsing and validating the result.

9.4 and 9.3

The json_build_object function was new to 9.5, so you have to aggregate and convert to an object in previous versions:

SELECT to_json(r)
FROM (
    SELECT
        json_agg(t.a) AS a,
        json_agg(t.b) AS b
    FROM t
) r

or

SELECT to_jsonb(r)
FROM (
    SELECT
        array_agg(t.a) AS a,
        array_agg(t.b) AS b
    FROM t
) r

depending on whether you want json or jsonb.

(9.3 does not have jsonb.)

9.2

In 9.2, not even to_json exists. You must use row_to_json:

SELECT row_to_json(r)
FROM (
    SELECT
        array_agg(t.a) AS a,
        array_agg(t.b) AS b
    FROM t
) r

Documentation

Find the documentation for the JSON functions in JSON functions.

json_agg is on the aggregate functions page.

Design

If performance is important, ensure you benchmark your queries against your own schema and data, rather than trust my testing.

Whether it's a good design or not really depends on your specific application. In terms of maintainability, I don't see any particular problem. It simplifies your app code and means there's less to maintain in that portion of the app. If PG can give you exactly the result you need out of the box, the only reason I can think of to not use it would be performance considerations. Don't reinvent the wheel and all.

Nulls

Aggregate functions typically give back NULL when they operate over zero rows. If this is a possibility, you might want to use COALESCE to avoid them. A couple of examples:

SELECT COALESCE(json_agg(t), '[]'::json) FROM t

Or

SELECT to_jsonb(COALESCE(array_agg(t), ARRAY[]::t[])) FROM t

Credit to Hannes Landeholm for pointing this out

What's the Kotlin equivalent of Java's String[]?

Some of the common ways to create a String array are

  1. var arr = Array(5){""}

This will create an array of 5 strings with initial values to be empty string.

  1. var arr = arrayOfNulls<String?>(5)

This will create an array of size 5 with initial values to be null. You can use String data to modify the array.

  1. var arr = arrayOf("zero", "one", "two", "three")

When you know the contents of array already then you can initialise the array directly.

  1. There is an easy way for creating an multi dimensional array of strings as well.

    var matrix = Array(5){Array(6) {""}}

    This is how you can create a matrix with 5 rows and 6 columns with initial values of empty string.

Enable VT-x in your BIOS security settings (refer to documentation for your computer)

Intel HAXM is required to run this AVD. VT-x is disabled in BIOS.

Enable VT-x in your BIOS security settings (refer to documentation for your computer).this error on android studio I dont no how to do Bios Security

Send JavaScript variable to PHP variable

It depends on the way your page behaves. If you want this to happens asynchronously, you have to use AJAX. Try out "jQuery post()" on Google to find some tuts.

In other case, if this will happen when a user submits a form, you can send the variable in an hidden field or append ?variableName=someValue" to then end of the URL you are opening. :

http://www.somesite.com/send.php?variableName=someValue

or

http://www.somesite.com/send.php?variableName=someValue&anotherVariable=anotherValue

This way, from PHP you can access this value as:

$phpVariableName = $_POST["variableName"];

for forms using POST method or:

$phpVariableName = $_GET["variableName"];

for forms using GET method or the append to url method I've mentioned above (querystring).

Using if elif fi in shell scripts

Change [ to [[, and ] to ]].

Using client certificate in Curl command

This is how I did it:

curl -v \
  --key ./admin-key.pem \
  --cert ./admin.pem \
  https://xxxx/api/v1/

fatal: This operation must be run in a work tree

You repository is bare, i.e. it does not have a working tree attached to it. You can clone it locally to create a working tree for it, or you could use one of several other options to tell Git where the working tree is, e.g. the --work-tree option for single commands, or the GIT_WORK_TREE environment variable. There is also the core.worktree configuration option but it will not work in a bare repository (check the man page for what it does).

# git --work-tree=/path/to/work/tree checkout master
# GIT_WORK_TREE=/path/to/work/tree git status

Running a simple shell script as a cronjob

Try,

 # cat test.sh
 #!/bin/bash
 /bin/touch file.txt

cron as:

 * * * * * /bin/sh /home/myUser/scripts/test.sh

And you can confirm this by:

 # tailf /var/log/cron

How to access /storage/emulated/0/

No need for third party apps

My Android 6.0 allows me to browse the intern memory without the need for third party apps. I simply do this*:

  1. "Settings"
  2. "Storage and USB"
  3. "Intern"
  4. [let it load a bit...]
  5. [scroll all the way down]
  6. "Browse"

* Words may not correspond to the standard English version ones, since I'm just freely translating them from Portuguese.

Note: At least in my phone, /storage/emulated/0 does not correspond to SD card, but to intern memory. This method did not work for my external card, but I never tried it with another phone.

Hope this helps!

How to install python3 version of package via pip on Ubuntu?

I had the same problem while trying to install pylab, and I have found this link

So what I have done to install pylab within Python 3 is:

python3 -m pip install SomePackage

It has worked properly, and as you can see in the link you can do this for every Python version you have, so I guess this solves your problem.

Sample database for exercise

Check out CodePlex for Microsoft SQL Server Community Projects & Samples

3rd party edit

On top of the link above you might look at

How to remove constraints from my MySQL table?

To add a little to Robert Knight's answer, since the title of the post itself doesn't mention foreign keys (and since his doesn't have complete code samples and since SO's comment code blocks don't show as well as the answers' code blocks), I'll add this for unique constraints. Either of these work to drop the constraint:

ALTER TABLE `table_name` DROP KEY `uc_name`;

or

ALTER TABLE `table_name` DROP INDEX `uc_name`;

Smooth scrolling with just pure css

You can do this with pure CSS but you will need to hard code the offset scroll amounts, which may not be ideal should you be changing page content- or should dimensions of your content change on say window resize.

You're likely best placed to use e.g. jQuery, specifically:

$('html, body').stop().animate({
   scrollTop: element.offset().top
}, 1000);

A complete implementation may be:

$('#up, #down').on('click', function(e){
    e.preventDefault();
    var target= $(this).get(0).id == 'up' ? $('#down') : $('#up');
    $('html, body').stop().animate({
       scrollTop: target.offset().top
    }, 1000);
});

Where element is the target element to scroll to and 1000 is the delay in ms before completion.

Demo Fiddle

The benefit being, no matter what changes to your content dimensions, the function will not need to be altered.

When is it appropriate to use C# partial classes?

Partial classes are primarily introduced to help Code generators, so we (users) don't end up loosing all our work / changes to the generated classes like ASP.NET's .designer.cs class each time we regenerate, almost all new tools that generate code LINQ, EntityFrameworks, ASP.NET use partial classes for generated code, so we can safely add or alter logic of these generated codes taking advantage of Partial classes and methods, but be very carefully before you add stuff to the generated code using Partial classes its easier if we break the build but worst if we introduce runtime errors. For more details check this http://www.4guysfromrolla.com/articles/071509-1.aspx

UTL_FILE.FOPEN() procedure not accepting path for directory?

You need to have your DBA modify the init.ora file, adding the directory you want to access to the 'utl_file_dir' parameter. Your database instance will then need to be stopped and restarted because init.ora is only read when the database is brought up.

You can view (but not change) this parameter by running the following query:

SELECT *
  FROM V$PARAMETER
  WHERE NAME = 'utl_file_dir'

Share and enjoy.

Detect Scroll Up & Scroll down in ListView

Here is a working modified version from some of the above-indicated solutions.

Add another class ListView:

package com.example.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AbsListView;

public class ListView extends android.widget.ListView {

    private OnScrollListener onScrollListener;
    private OnDetectScrollListener onDetectScrollListener;

    public ListView(Context context) {
        super(context);
        onCreate(context, null, null);
    }

    public ListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        onCreate(context, attrs, null);
    }

    public ListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        onCreate(context, attrs, defStyle);
    }

    @SuppressWarnings("UnusedParameters")
    private void onCreate(Context context, AttributeSet attrs, Integer defStyle) {
        setListeners();
    }

    private void setListeners() {
        super.setOnScrollListener(new OnScrollListener() {

            private int oldTop;
            private int oldFirstVisibleItem;

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                if (onScrollListener != null) {
                    onScrollListener.onScrollStateChanged(view, scrollState);
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if (onScrollListener != null) {
                    onScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
                }

                if (onDetectScrollListener != null) {
                    onDetectedListScroll(view, firstVisibleItem);
                }
            }

            private void onDetectedListScroll(AbsListView absListView, int firstVisibleItem) {
                View view = absListView.getChildAt(0);
                int top = (view == null) ? 0 : view.getTop();

                if (firstVisibleItem == oldFirstVisibleItem) {
                    if (top > oldTop) {
                        onDetectScrollListener.onUpScrolling();
                    } else if (top < oldTop) {
                        onDetectScrollListener.onDownScrolling();
                    }
                } else {
                    if (firstVisibleItem < oldFirstVisibleItem) {
                        onDetectScrollListener.onUpScrolling();
                    } else {
                        onDetectScrollListener.onDownScrolling();
                    }
                }

                oldTop = top;
                oldFirstVisibleItem = firstVisibleItem;
            }
        });
    }

    @Override
    public void setOnScrollListener(OnScrollListener onScrollListener) {
        this.onScrollListener = onScrollListener;
    }

    public void setOnDetectScrollListener(OnDetectScrollListener onDetectScrollListener) {
        this.onDetectScrollListener = onDetectScrollListener;
    }
}

And an interface:

public interface OnDetectScrollListener {

    void onUpScrolling();

    void onDownScrolling();
}

And finally how to use:

com.example.view.ListView listView = (com.example.view.ListView) findViewById(R.id.list);
listView.setOnDetectScrollListener(new OnDetectScrollListener() {
    @Override
    public void onUpScrolling() {
        /* do something */
    }

    @Override
    public void onDownScrolling() {
        /* do something */
    }
});

In your XML layout:

<com.example.view.ListView
    android:id="@+id/list"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

This is my first topic, do not judge me harshly. =)

Get User's Current Location / Coordinates

import Foundation
import CoreLocation

enum Result<T> {
  case success(T)
  case failure(Error)
}

final class LocationService: NSObject {
    private let manager: CLLocationManager

    init(manager: CLLocationManager = .init()) {
        self.manager = manager
        super.init()
        manager.delegate = self
    }

    var newLocation: ((Result<CLLocation>) -> Void)?
    var didChangeStatus: ((Bool) -> Void)?

    var status: CLAuthorizationStatus {
        return CLLocationManager.authorizationStatus()
    }

    func requestLocationAuthorization() {
        manager.delegate = self
        manager.desiredAccuracy = kCLLocationAccuracyBest
        manager.requestWhenInUseAuthorization()
        if CLLocationManager.locationServicesEnabled() {
            manager.startUpdatingLocation()
            //locationManager.startUpdatingHeading()
        }
    }

    func getLocation() {
        manager.requestLocation()
    }

    deinit {
        manager.stopUpdatingLocation()
    }

}

 extension LocationService: CLLocationManagerDelegate {
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        newLocation?(.failure(error))
        manager.stopUpdatingLocation()
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        if let location = locations.sorted(by: {$0.timestamp > $1.timestamp}).first {
            newLocation?(.success(location))
        }
        manager.stopUpdatingLocation()
    }

    func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
        switch status {
        case .notDetermined, .restricted, .denied:
            didChangeStatus?(false)
        default:
            didChangeStatus?(true)
        }
    }
}

Needs to write this code in required ViewController.

 //NOTE:: Add permission in info.plist::: NSLocationWhenInUseUsageDescription


let locationService = LocationService()

 @IBAction func action_AllowButtonTapped(_ sender: Any) {
     didTapAllow()
 }

 func didTapAllow() {
     locationService.requestLocationAuthorization()
 }

 func getCurrentLocationCoordinates(){
   locationService.newLocation = {result in
     switch result {
      case .success(let location):
      print(location.coordinate.latitude, location.coordinate.longitude)
      case .failure(let error):
      assertionFailure("Error getting the users location \(error)")
   }
  }
}

func getCurrentLocationCoordinates() {
    locationService.newLocation = { result in
        switch result {
        case .success(let location):
            print(location.coordinate.latitude, location.coordinate.longitude)
            CLGeocoder().reverseGeocodeLocation(location, completionHandler: {(placemarks, error) -> Void in
                if error != nil {
                    print("Reverse geocoder failed with error" + (error?.localizedDescription)!)
                    return
                }
                if (placemarks?.count)! > 0 {
                    print("placemarks", placemarks!)
                    let pmark = placemarks?[0]
                    self.displayLocationInfo(pmark)
                } else {
                    print("Problem with the data received from geocoder")
                }
            })
        case .failure(let error):
            assertionFailure("Error getting the users location \(error)")
        }
    }
}

Need to find element in selenium by css

By.cssSelector(".ban") or By.cssSelector(".hot") or By.cssSelector(".ban.hot") should all select it unless there is another element that has those classes.

In CSS, .name means find an element that has a class with name. .foo.bar.baz means to find an element that has all of those classes (in the same element).

However, each of those selectors will select only the first element that matches it on the page. If you need something more specific, please post the HTML of the other elements that have those classes.

Permissions error when connecting to EC2 via SSH on Mac OSx

If you have a PPK file working on a PC, then export it as OpenSSH file using puttygen.exe for PC and use that on Mac (any Unix machine).

I was getting the same error --

debug1: Authentications that can continue: publickey,gssapi-with-mic
debug1: Next authentication method: publickey
debug1: Trying private key: ec2-keypair
debug1: read PEM private key done: type RSA
debug1: Authentications that can continue: publickey,gssapi-with-mic
debug1: No more authentication methods to try.
Permission denied (publickey,gssapi-with-mic)

As I was using a PPK file on Windows, I followed the steps as described above and Bingo!

$ ssh -i ec2-openssh-key root@ec2-instance-ip

Android Room - simple select query - Cannot access database on the main thread

You have to execute request in background. A simple way could be using an Executors :

Executors.newSingleThreadExecutor().execute { 
   yourDb.yourDao.yourRequest() //Replace this by your request
}

adb connection over tcp not working now

I couldn't do it on a Galaxy S3 (non rooted).

For me it would hang saying...

restaring in tcp mode

So i found this series of commands quite useful.

First disconnect your device, start from scratch (cmd in admin mode and all the stuff).

connect your device and write in CMD/Terminal:

adb kill-server

control should return as normal. Now type and enter

adb tcpip 5555

you will see..

  • daemon not running. starting it now on port 5037 *
  • daemon started successfully * restarting in TCP mode port: 5555

and then connect device with

adb connect <IP>

That's how it worked for me after a lot of hassle!

UPDATE FOR ANDROID STUDIO

I noticed this doesn't work sometimes, even after correctly repeating steps a number of times. Catch was; sometimes ADB is yet not initialized by Studio unless, Android Tab at the bottom is opened and you see "Initializing Android Studio".

You will large Initializing text.

How do I remove  from the beginning of a file?

  1. Copy the text of your filename.css file.
  2. Close your css file.
  3. Rename it filename2.css to avoid a filename clash.
  4. In MS Notepad or Wordpad, create a new file.
  5. Paste the text into it.
  6. Save it as filename.css, selecting UTF-8 from the encoding options.
  7. Upload filename.css.

How do I set a column value to NULL in SQL Server Management Studio?

I think @Zack properly answered the question but just to cover all the bases:

Update myTable set MyColumn = NULL

This would set the entire column to null as the Question Title asks.

To set a specific row on a specific column to null use:

Update myTable set MyColumn = NULL where Field = Condition.

This would set a specific cell to null as the inner question asks.

Face recognition Library

If your project is on a movie or TV, or anything that has a script, it looks like you definitely want to look at the work of Mark Everingham et al.. The software is available, as are the results on a Buffy episode.

How do I get the classes of all columns in a data frame?

You can simple make use of lapply or sapply builtin functions.

lapply will return you a list -

lapply(dataframe,class)

while sapply will take the best possible return type ex. Vector etc -

sapply(dataframe,class)

Both the commands will return you all the column names with their respective class.

Send data from activity to fragment in Android

Smartest tried and tested way of passing data between fragments and activity is to create a variables,example:

class StorageUtil {
  public static ArrayList<Employee> employees;
}

Then to pass data from fragment to activity, we do so in the onActivityCreated method:

//a field created in the sending fragment
ArrayList<Employee> employees;

@Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
         employees=new ArrayList();

       //java 7 and above syntax for arraylist else use employees=new ArrayList<Employee>() for java 6 and below

     //Adding first employee
        Employee employee=new Employee("1","Andrew","Sam","1984-04-10","Male","Ghanaian");
        employees.add(employee);

      //Adding second employee
       Employee employee=new Employee("1","Akuah","Morrison","1984-02-04","Female","Ghanaian");
         employees.add(employee);

        StorageUtil.employees=employees;
    }

Now you can get the value of StorageUtil.employees from everywhere. Goodluck!

How to tell if UIViewController's view is visible

The approach that I used for a modal presented view controller was to check the class of the presented controller. If the presented view controller was ViewController2 then I would execute some code.

UIViewController *vc = [self presentedViewController];

if ([vc isKindOfClass:[ViewController2 class]]) {
    NSLog(@"this is VC2");
}

Confirm deletion using Bootstrap 3 modal box

simple way to use modals is with eModal!

Ex from github:

  1. Link to eModal.js <script src="//rawgit.com/saribe/eModal/master/dist/eModal.min.js"></script>

_x000D_
_x000D_
    var options = {_x000D_
            message: "The famouse question?",_x000D_
            title: 'Header title',_x000D_
            size: 'sm',_x000D_
            callback: function(result) { result ? doActionTrue(result) :    doActionFalse(); },_x000D_
            subtitle: 'smaller text header',_x000D_
            label: "True"   // use the possitive lable as key_x000D_
            //..._x000D_
        };_x000D_
                     _x000D_
    eModal.confirm(options);
_x000D_
 <link href="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.1/css/bootstrap.min.css" rel="stylesheet"/>_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<script src="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.1/js/bootstrap.min.js"></script>_x000D_
<script src="//rawgit.com/saribe/eModal/master/dist/eModal.min.js"></script>
_x000D_
_x000D_
_x000D_

Tip: You can use change the default label name! { label: 'Yes' | 'True'| 'OK' }

Reactive forms - disabled attribute

I found that I needed to have a default value, even if it was an empty string for it to work. So this:

this.registerForm('someName', {
  firstName: new FormControl({disabled: true}),
});

...had to become this:

this.registerForm('someName', {
  firstName: new FormControl({value: '', disabled: true}),
});

See my question (which I don't believe is a duplicate): Passing 'disabled' in form state object to FormControl constructor doesn't work

Route [login] not defined

Try to add this at Header of your request: Accept=application/json postman or insomnia add header

How to loop through file names returned by find?

# Doesn't handle whitespace
for x in `find . -name "*.txt" -print`; do
  process_one $x
done

or

# Handles whitespace and newlines
find . -name "*.txt" -print0 | xargs -0 -n 1 process_one

Conversion failed when converting the varchar value to data type int in sql

I got the same error message. In my case, it was due to not using quotes.

Although the column was supposed to have only numbers, it was a Varchar column, and one of the rows had a letter in it.

So I was doing this:

select * from mytable where myid = 1234

While I should be doing this:

select * from mytable where myid = '1234'

If the column had all numbers, the conversion would have worked, but not in this case.

How do you convert CString and std::string std::wstring to each other?

One interesting approach is to cast CString to CStringA inside a string constructor. Unlike std::string s((LPCTSTR)cs); this will work even if _UNICODE is defined. However, if that is the case, this will perform conversion from Unicode to ANSI, so it is unsafe for higher Unicode values beyond the ASCII character set. Such conversion is subject to the _CSTRING_DISABLE_NARROW_WIDE_CONVERSION preprocessor definition. https://msdn.microsoft.com/en-us/library/5bzxfsea.aspx

        CString s1("SomeString");
        string s2((CStringA)s1);

CSS height 100% percent not working

You aren't specifying the "height" of your html. When you're assigning a percentage in an element (i.e. divs) the css compiler needs to know the size of the parent element. If you don't assign that, you should see divs without height.

The most common solution is to set the following property in css:

html{
    height: 100%;
    margin: 0;
    padding: 0;
}

You are saying to the html tag (html is the parent of all the html elements) "Take all the height in the HTML document"

I hope I helped you. Cheers

How to make an inline-block element fill the remainder of the line?

A modern solution using flexbox:

_x000D_
_x000D_
.container {_x000D_
    display: flex;_x000D_
}_x000D_
.container > div {_x000D_
    border: 1px solid black;_x000D_
    height: 10px;_x000D_
}_x000D_
_x000D_
.left {_x000D_
   width: 100px;_x000D_
}_x000D_
_x000D_
.right {_x000D_
    width: 100%;_x000D_
    background-color:#ddd;_x000D_
}
_x000D_
<div class="container">_x000D_
  <div class="left"></div>_x000D_
  <div class="right"></div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

http://jsfiddle.net/m5Xz2/100/

Why am I seeing "TypeError: string indices must be integers"?

data is a dict object. So, iterate over it like this:

Python 2

for key, value in data.iteritems():
    print key, value

Python 3

for key, value in data.items():
    print(key, value)

Joining three tables using MySQL

Don't join like that. It's a really really bad practice!!! It will slow down the performance in fetching with massive data. For example, if there were 100 rows in each tables, database server have to fetch 100x100x100 = 1000000 times. It had to fetch for 1 million times. To overcome that problem, join the first two table that can fetch result in minimum possible matching(It's up to your database schema). Use that result in Subquery and then join it with the third table and fetch it. For the very first join --> 100x100= 10000 times and suppose we get 5 matching result. And then we join the third table with the result --> 5x100 = 500. Total fetch = 10000+500 = 10200 times only. And thus, the performance went up!!!

Get mouse wheel events in jQuery?

Here is a vanilla solution. Can be used in jQuery if the event passed to the function is event.originalEvent which jQuery makes available as property of the jQuery event. Or if inside the callback function under we add before first line: event = event.originalEvent;.

This code normalizes the wheel speed/amount and is positive for what would be a forward scroll in a typical mouse, and negative in a backward mouse wheel movement.

Demo: http://jsfiddle.net/BXhzD/

var wheel = document.getElementById('wheel');

function report(ammout) {
    wheel.innerHTML = 'wheel ammout: ' + ammout;
}

function callback(event) {
    var normalized;
    if (event.wheelDelta) {
        normalized = (event.wheelDelta % 120 - 0) == -0 ? event.wheelDelta / 120 : event.wheelDelta / 12;
    } else {
        var rawAmmount = event.deltaY ? event.deltaY : event.detail;
        normalized = -(rawAmmount % 3 ? rawAmmount * 10 : rawAmmount / 3);
    }
    report(normalized);
}

var event = 'onwheel' in document ? 'wheel' : 'onmousewheel' in document ? 'mousewheel' : 'DOMMouseScroll';
window.addEventListener(event, callback);

There is also a plugin for jQuery, which is more verbose in the code and some extra sugar: https://github.com/brandonaaron/jquery-mousewheel

jquery/javascript convert date string to date

I would grab date.js or else you will need to roll your own formatting function.

What's the difference between disabled="disabled" and readonly="readonly" for HTML form input fields?

If the value of a disabled textbox needs to be retained when a form is cleared (reset), disabled = "disabled" has to be used, as read-only textbox will not retain the value

For Example:

HTML

Textbox

<input type="text" id="disabledText" name="randombox" value="demo" disabled="disabled" />

Reset button

<button type="reset" id="clearButton">Clear</button>

In the above example, when Clear button is pressed, disabled text value will be retained in the form. Value will not be retained in the case of input type = "text" readonly="readonly"

How do you add an image?

In order to add attributes, XSL wants

<xsl:element name="img">
     (attributes)
</xsl:element>

instead of just

<img>
     (attributes)
</img>

Although, yes, if you're just copying the element as-is, you don't need any of that.

A fatal error has been detected by the Java Runtime Environment: SIGSEGV, libjvm

after hardware check on the server and it was found out that memory had gone bad, replaced the memory and the server is now fully accessible.

How to split a python string on new line characters

a.txt

this is line 1
this is line 2

code:

Python 3.4.0 (default, Mar 20 2014, 22:43:40) 
[GCC 4.6.3] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> file = open('a.txt').read()
>>> file
>>> file.split('\n')
['this is line 1', 'this is line 2', '']

I'm on Linux, but I guess you just use \r\n on Windows and it would also work

Different ways of clearing lists

It appears to me that del will give you the memory back, while assigning a new list will make the old one be deleted only when the gc runs.matter.

This may be useful for large lists, but for small list it should be negligible.

Edit: As Algorias, it doesn't matter.

Note that

del old_list[ 0:len(old_list) ]

is equivalent to

del old_list[:]

Is a URL allowed to contain a space?

URLs are defined in RFC 3986, though other RFCs are relevant as well but RFC 1738 is obsolete.

They may not have spaces in them, along with many other characters. Since those forbidden characters often need to be represented somehow, there is a scheme for encoding them into a URL by translating them to their ASCII hexadecimal equivalent with a "%" prefix.

Most programming languages/platforms provide functions for encoding and decoding URLs, though they may not properly adhere to the RFC standards. For example, I know that PHP does not.

How to delete Tkinter widgets from a window?

You can call pack_forget to remove a widget (if you use pack to add it to the window).

Example:

from tkinter import *

root = Tk()

b = Button(root, text="Delete me", command=lambda: b.pack_forget())
b.pack()

root.mainloop()

If you use pack_forget, you can later show the widget again calling pack again. If you want to permanently delete it, call destroy on the widget (then you won't be able to re-add it).

If you use the grid method, you can use grid_forget or grid_remove to hide the widget.

EnterKey to press button in VBA Userform

Be sure to avoid "magic numbers" whenever possible, either by defining your own constants, or by using the built-in vbXXX constants.

In this instance we could use vbKeyReturn to indicate the enter key's keycode (replacing YourInputControl and SubToBeCalled).

   Private Sub YourInputControl_KeyDown(ByVal KeyCode As MSForms.ReturnInteger, ByVal Shift As Integer)
        If KeyCode = vbKeyReturn Then
             SubToBeCalled
        End If
   End Sub

This prevents a whole category of compatibility issues and simple typos, especially because VBA capitalizes identifiers for us.

Cheers!

How can I get query string values in JavaScript?

function GET() {
        var data = [];
        for(x = 0; x < arguments.length; ++x)
            data.push(location.href.match(new RegExp("/\?".concat(arguments[x],"=","([^\n&]*)")))[1])
                return data;
    }


example:
data = GET("id","name","foo");
query string : ?id=3&name=jet&foo=b
returns:
    data[0] // 3
    data[1] // jet
    data[2] // b
or
    alert(GET("id")[0]) // return 3

Change onClick attribute with javascript

Well, just do this and your problem is solved :

document.getElementById('buttonLED'+id).setAttribute('onclick','writeLED(1,1)')

Have a nice day XD

Python Loop: List Index Out of Range

  1. In your for loop, you're iterating through the elements of a list a. But in the body of the loop, you're using those items to index that list, when you actually want indexes.
    Imagine if the list a would contain 5 items, a number 100 would be among them and the for loop would reach it. You will essentially attempt to retrieve the 100th element of the list a, which obviously is not there. This will give you an IndexError.

We can fix this issue by iterating over a range of indexes instead:

for i in range(len(a))

and access the a's items like that: a[i]. This won't give any errors.

  1. In the loop's body, you're indexing not only a[i], but also a[i+1]. This is also a place for a potential error. If your list contains 5 items and you're iterating over it like I've shown in the point 1, you'll get an IndexError. Why? Because range(5) is essentially 0 1 2 3 4, so when the loop reaches 4, you will attempt to get the a[5] item. Since indexing in Python starts with 0 and your list contains 5 items, the last item would have an index 4, so getting the a[5] would mean getting the sixth element which does not exist.

To fix that, you should subtract 1 from len(a) in order to get a range sequence 0 1 2 3. Since you're using an index i+1, you'll still get the last element, but this way you will avoid the error.

  1. There are many different ways to accomplish what you're trying to do here. Some of them are quite elegant and more "pythonic", like list comprehensions:

b = [a[i] + a[i+1] for i in range(len(a) - 1)]

This does the job in only one line.

How to format a number 0..9 to display with 2 digits (it's NOT a date)

If you need to print the number you can use printf

System.out.printf("%02d", num);

You can use

String.format("%02d", num);

or

(num < 10 ? "0" : "") + num;

or

(""+(100+num)).substring(1);

node.js shell command execution

You're not actually returning anything from your run_cmd function.

function run_cmd(cmd, args, done) {
    var spawn = require("child_process").spawn;
    var child = spawn(cmd, args);
    var result = { stdout: "" };
    child.stdout.on("data", function (data) {
            result.stdout += data;
    });
    child.stdout.on("end", function () {
            done();
    });
    return result;
}

> foo = run_cmd("ls", ["-al"], function () { console.log("done!"); });
{ stdout: '' }
done!
> foo.stdout
'total 28520...'

Works just fine. :)

Disable activity slide-in animation when launching new activity?

Just specify Intent.FLAG_ACTIVITY_NO_ANIMATION flag when starting

How to detect running app using ADB command

You can use

adb shell ps | grep apps | awk '{print $9}'

to produce an output like:

com.google.process.gapps
com.google.android.apps.uploader
com.google.android.apps.plus
com.google.android.apps.maps
com.google.android.apps.maps:GoogleLocationService
com.google.android.apps.maps:FriendService
com.google.android.apps.maps:LocationFriendService

adb shell ps returns a list of all running processes on the android device, grep apps searches for any row with contains "apps", as you can see above they are all com.google.android.APPS. or GAPPS, awk extracts the 9th column which in this case is the package name.

To search for a particular package use

adb shell ps | grep PACKAGE.NAME.HERE | awk '{print $9}'

i.e adb shell ps | grep com.we7.player | awk '{print $9}'

If it is running the name will appear, if not there will be no result returned.

Django 1.7 - "No migrations to apply" when run migrate after makemigrations

This is a very confusing topic. django stores all applied migrations in a table called django_migrations. perform this sql ( i am using postgres . so in query tool section)

select * from django_migrations where app='your appname'  (app in which u have issue with).

This will list all applied migrations for that app.
Go to your app/migration folder and check all migrations . find the migration file associated with your error . file where your table was created or column added or modified.
look for the id of this migration file in django_migrations table( select * from django_migrations where app='your app') .

Then do :

delete from django_migrations where id='id of your migration';

delete multiple id's if you have multiple migrations file associated with your issue.

now reapply migrate

Python manage.py migrate yourappname

second option

  1. Drop tables in your app where you have issue.

  2. delete all migrations for that app from app/migrations folder.(don't delete init.py from that folder).

  3. now run

    python manage.py makemigrations appname

  4. now run

python manage.py migrate appname

NoClassDefFoundError - Eclipse and Android

I didn't have to put the jar-library in assets or lib(s), but only tick the box for this jar in Properties -> Java Build Path -> "Order and Export" (it was listed before, but not selected)

TypeError: not all arguments converted during string formatting python

In addition to the other two answers, I think the indentations are also incorrect in the last two conditions. The conditions are that one name is longer than the other and they need to start with 'elif' and with no indentations. If you put it within the first condition (by giving it four indentations from the margin), it ends up being contradictory because the lengths of the names cannot be equal and different at the same time.

    else:
        print ("The names are different, but are the same length")
elif len(name1) > len(name2):
    print ("{0} is longer than {1}".format(name1, name2))

SQL LEFT-JOIN on 2 fields for MySQL

Let's try this way:

select 
    a.ip, 
    a.os, 
    a.hostname, 
    a.port, 
    a.protocol, 
    b.state
from a
left join b 
    on a.ip = b.ip 
        and a.port = b.port /*if you has to filter by columns from right table , then add this condition in ON clause*/
where a.somecolumn = somevalue /*if you have to filter by some column from left table, then add it to where condition*/

So, in where clause you can filter result set by column from right table only on this way:

...
where b.somecolumn <> (=) null

What is duck typing?

Tree Traversal with duck typing technique

def traverse(t):
    try:
        t.label()
    except AttributeError:
        print(t, end=" ")
    else:
        # Now we know that t.node is defined
        print('(', t.label(), end=" ")
        for child in t:
            traverse(child)
        print(')', end=" ")

How to get row index number in R?

I'm interpreting your question to be about getting row numbers.

  • You can try as.numeric(rownames(df)) if you haven't set the rownames. Otherwise use a sequence of 1:nrow(df).
  • The which() function converts a TRUE/FALSE row index into row numbers.

navbar color in Twitter Bootstrap

that is what i do

.navbar-inverse .navbar-inner {
  background-color: #E27403; /* it's flat*/
 background-image: none;
}

.navbar-inverse .navbar-inner {
  background-image: -ms-linear-gradient(top, #E27403, #E49037);
  background-image: -webkit-linear-gradient(top, #E27403, #E49037);
  background-image: linear-gradient(to bottom, #E27403, #E49037);
}

it works well for all navigator you can see demo here http://caverne.fr on the top

Multiple WHERE clause in Linq

@Theo

The LINQ translator is smart enough to execute:

.Where(r => r.UserName !="XXXX" && r.UsernName !="YYYY")

I've test this in LinqPad ==> YES, Linq translator is smart enough :))

C++ obtaining milliseconds time on Linux -- clock() doesn't seem to work properly

This should work...tested on a mac...

#include <stdio.h>
#include <sys/time.h>

int main() {
        struct timeval tv;
        struct timezone tz;
        struct tm *tm;
        gettimeofday(&tv,&tz);
        tm=localtime(&tv.tv_sec);
        printf("StartTime: %d:%02d:%02d %d \n", tm->tm_hour, tm->tm_min, tm->tm_sec, tv.tv_usec);
}

Yeah...run it twice and subtract...

How can I get the current contents of an element in webdriver

In Java its Webelement.getText() . Not sure about python.

powershell mouse move does not prevent idle mode

I've added a notification that you can easily enable / disable just setting its variable to $true or $false. Also the mouse cursor moves 1 px right and then 1 px left so it basically stays in the same place even after several iterations.

# Lines needed for the notification
[System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
Add-Type -AssemblyName System.Windows.Forms 
$isNotificationOn = $true

$secondsBetweenMouseMoves = 6
$Pos = [System.Windows.Forms.Cursor]::Position
$PosDelta = 1
$logFilename = "previousMouseMoverAction.txt"
$errorLogFilename = "mouseMoverLog.txt"

if (!(Test-Path "$PSScriptRoot\$logFilename")) {
   New-Item -path $PSScriptRoot -name $logFilename -type "file" -value "right"
   Write-Host "Warning: previousMouseMoverAction.txt missing, created a new one."
}

$previousPositionChangeAction = Get-Content -Path $PSScriptRoot\$logFilename

if ($previousPositionChangeAction -eq "left") {
    $PosDelta = 1
    Set-Content -Path $PSScriptRoot\$logFilename -Value 'right'
} else {
    $PosDelta = -1
    Set-Content -Path $PSScriptRoot\$logFilename -Value 'left'
}

for ($i = 0; $i -lt $secondsBetweenMouseMoves; $i++) {
    [System.Windows.Forms.Cursor]::Position = New-Object System.Drawing.Point((($Pos.X) + $PosDelta) , $Pos.Y)
    if ($isNotificationOn) {
        # Sending a notification to the user
        $global:balloon = New-Object System.Windows.Forms.NotifyIcon
        $path = (Get-Process -id $pid).Path
        $balloon.Icon = [System.Drawing.Icon]::ExtractAssociatedIcon($path) 
        $balloon.BalloonTipIcon = [System.Windows.Forms.ToolTipIcon]::Warning 
        $balloon.BalloonTipText = 'I have just moved your cheese...'
        $balloon.BalloonTipTitle = "Attention, $Env:USERNAME" 
        $balloon.Visible = $true 
        $balloon.ShowBalloonTip(3000)
    }
}

How to compare strings in Bash

Using variables in if statements

if [ "$x" = "valid" ]; then
  echo "x has the value 'valid'"
fi

If you want to do something when they don't match, replace = with !=. You can read more about string operations and arithmetic operations in their respective documentation.

Why do we use quotes around $x?

You want the quotes around $x, because if it is empty, your Bash script encounters a syntax error as seen below:

if [ = "valid" ]; then

Non-standard use of == operator

Note that Bash allows == to be used for equality with [, but this is not standard.

Use either the first case wherein the quotes around $x are optional:

if [[ "$x" == "valid" ]]; then

or use the second case:

if [ "$x" = "valid" ]; then

Is div inside list allowed?

I see you would want to do this if you wanted to make, say, the whole box of a menu item clickable. I used to insert an 'li' tag in 'a' tags to do this but this seems more valid.

Postgresql - change the size of a varchar column to lower length

I was facing the same problem trying to truncate a VARCHAR from 32 to 8 and getting the ERROR: value too long for type character varying(8). I want to stay as close to SQL as possible because I'm using a self-made JPA-like structure that we might have to switch to different DBMS according to customer's choices (PostgreSQL being the default one). Hence, I don't want to use the trick of altering System tables.

I ended using the USING statement in the ALTER TABLE:

ALTER TABLE "MY_TABLE" ALTER COLUMN "MyColumn" TYPE varchar(8)
USING substr("MyColumn", 1, 8)

As @raylu noted, ALTER acquires an exclusive lock on the table so all other operations will be delayed until it completes.

Regarding Java switch statements - using return and omitting breaks in each case

Though the question is old enough it still can be referenced nowdays.

Semantically that is exactly what Java 12 introduced (https://openjdk.java.net/jeps/325), thus, exactly in that simple example provided I can't see any problem or cons.